mRNA vaccines for infectious diseases: principles, delivery and clinical translation

In the paper

“higher frequency of fever, fatigue and chills in participants than BNT162b2 (ref.124)”

What the sources say

• Supported

  The Systemic events section says responses to BNT162b2 were milder than to BNT162b1 and gives a substantially lower fever frequency after the second 30 µg dose. Its discussion of BNT162b1 includes chills and fatigue, and the Figure 3 caption identifies fever, chills, and fatigue as the events compared. (LLM, conf=0.90)

  cites [124] Walsh, E. E. et al. Safety and immunogenicity of two RNA-based covid-19 vaccine candidates. N. Engl. J. Med. 383, 2439–2450 (2020). source

In the paper

“Importantly, poorly designed Zika virus vaccines can increase the infectiousness of the dengue virus154.”

What the sources say

• Supported

  Section 5.2 (Zika Virus; page not provided) explains that antibodies elicited by a Zika vaccine can enhance dengue infection through antibody-dependent enhancement. It reports that serum from mice given a vaccine encoding wild-type Zika proteins enhanced dengue disease in laboratory and animal studies, while a modified design largely avoided that effect. The evidence supports the claim as a potential consequence of vaccine design, not as a demonstrated outcome in vaccinated humans. (LLM, conf=0.87)

  cites [154] Wollner, C. J. & Richner, J. M. mRNA vaccines against flaviviruses. Vaccines 9, 1–13 (2021). source

In the paper

“Although some candidates have failed clinical trials owing to insufficient neutralizing antibody titres174, newfound structural insights into F protein conformation have revealed that vaccinating against the prefusion conformation elicits superior neutralizing antibody response175–178.”

What the sources say

• Not checked yetcites [175] Crank, M. C. et al. A proof of concept for structure-based vaccine design targeting RSV in humans. Science 365, 505–509 (2019). source
• Partly supported

  The paper reports that immunization presenting native F elicited a potent prefusion-specific antibody, 5C4. It says prefusion-stabilized vaccine antigens may further improve antibody elicitation, but does not show that vaccination with prefusion F produces a superior neutralizing antibody response compared with another F conformation (passage [1], section labeled Abstract; no page supplied). (LLM, conf=0.88)

  cites [176] McLellan, J. S. et al. Structure of RSV fusion glycoprotein trimer bound to a prefusion-specific neutralizing antibody. Science 340, 1113–1117 (2013). sourceExperimental — accuracy not yet measured
• Supported

  The Immunogenicity of Antigenic Site Ø-Stabilized RSV F section reports that stabilized prefusion F elicited higher neutralizing antibody titers than postfusion F in mice and rhesus macaques. The claim reflects those comparisons; the experiments were in animals, not humans. (LLM, conf=0.94)

  cites [177] McLellan, J. S. et al. Structure-based design of a fusion glycoprotein vaccine for respiratory syncytial virus. Science 342, 592–598 (2013). source
• Supported

  The Results section (“Immunogenicity and efficacy of prefusion RSV F protein”) reports significantly higher neutralizing-antibody titers in mice immunized with prefusion RSV F than with postfusion F, including a 10-fold difference for adjuvanted constructs. The Discussion links the stabilized prefusion protein to structural insights and likewise reports higher neutralizing titers in rodents. (LLM, conf=0.94)

  cites [178] Krarup, A. et al. A highly stable prefusion RSV F vaccine derived from structural analysis of the fusion mechanism. Nat. Commun. 6, 1–12 (2015). source

In the paper

“which is about two- to fourfold more than is typically seen with more traditional vaccines214.”

What the sources say

• Supported

  The Results report 1.31 anaphylaxis cases per million doses across the vaccines studied, providing the traditional-vaccine baseline for the citing sentence. The paper predates mRNA COVID-19 vaccines; the two- to fourfold comparison uses an mRNA rate supplied by the citing document, not a rate attributed to this source. (LLM, conf=0.87)

  cites [214] McNeil, M. M. et al. Risk of anaphylaxis after vaccination in children and adults. J. Allergy Clin. Immunol. 137, 868–878 (2016). source

In the paper

“current acceptance rates of 56–75%245 may be insufficient to reach at least 80–90% coverage246, the threshold thought to be necessary for herd immunity against SARS-CoV-2.”

What the sources say

• Supported

  Citation 245 is attached to the US acceptance-rate estimate. The Results (§3.3) report US rates of 56.9% in April and 67.0–75.0% in May, consistent with the cited 56–75% range. The 80–90% herd-immunity threshold has a separate citation and is not attributed to this source. (LLM, conf=0.93)

  cites [245] Sallam, M. Covid-19 vaccine hesitancy worldwide: a concise systematic review of vaccine acceptance rates. Vaccines 9, 1–15 (2021). source
• Partly supported

  The “SARS-CoV-2 variants and herd immunity” section estimates a threshold of approximately 80% for the emerging variants, without mitigating interventions, but does not give an 80–90% range; it estimates about 70% for the earlier strain. The 56–75% US acceptance rate has a separate citation in the citing sentence and is not attributed to this source. (LLM, conf=0.88)

  cites [246] Lippi, G. & Henry, B. M. How will emerging SARS-CoV-2 variants impact herd immunity? Ann. Transl. Med. 9, 585–585 (2021). sourceExperimental — accuracy not yet measured

In the paper

“Despite their evident success, however, conventional vaccines do not effectively tackle pathogens such as the malaria parasite Plasmodium falciparum, hepatitis C and human immunodeficiency virus (HIV), which evade immune surveillance2.”

What the sources say

• Not checked yetcites [2] Kennedy, R. B., Ovsyannikova, I. G., Palese, P. & Poland, G. A. Current challenges in vaccinology. Front. Immunol. 11, 1181 (2020). source

In the paper

“and enabling the targeting of multiple microbes or viral variants with a single formulation8.”

What the sources say

• Not checked yetcites [8] Wu, K. et al. Variant SARS-CoV-2 mRNA vaccines confer broad neutralization as primary or booster series in mice. bioRxiv https://www.biorxiv.org/content/10.1101/2021.04.13.439482v1 (2021). source

In the paper

“Although it is now clear that mRNA vaccines can rapidly and safely protect patients from infectious disease, additional research is required to optimize mRNA design, intracellular delivery and applications beyond SARS-CoV-2 prophylaxis.”

In the paper

“For example, a 5 litre bioreactor can produce almost a million mRNA vaccine doses in a single reaction6.”

What the sources say

• Not checked yetcites [6] Kis, Z., Kontoravdi, C., Dey, A. K., Shattock, R. & Shah, N. Rapid development and deployment of high-volume vaccines for pandemic response. J. Adv. Manuf. Process. 2, e10060 (2020). source

In the paper

“mRNA vaccines can be manufactured in a cell-free manner, allowing rapid, scalable and cost-effective production.”

In the paper

“Although replacement of rare codons is an attractive optimization strategy, it must be used judiciously. This is because, in the case of some proteins, the slower translation rate of rare codons is necessary for proper protein folding22.”

What the sources say

• Not checked yetcites [22] Spencer, P. S., Siller, E., Anderson, J. F. & Barral, J. M. Silent substitutions predictably alter translation elongation rates and protein folding efficiencies. J. Mol. Biol. 422, 328–335 (2012). source

In the paper

“Specifically, unmodified mRNA is recognized by pattern recognition receptors, such as Toll-like receptor 3 (TLR3), TLR7 and TLR8, and the retinoic acid-inducible gene I (RIGI) receptor.”

In the paper

“Both the Moderna and Pfizer–BioNTech SARS-CoV-2 vaccines, which produced >94% efficacy in phase III clinical trials25, contain nucleoside-modified mRNAs.”

What the sources say

• Not checked yetcites [25] Buschmann, M. D. et al. Nanomaterial delivery systems for mRNA vaccines. Vaccines 9, 65 (2021). source

In the paper

“Their lightning-fast development was facilitated by three factors: decades of previous research, large financial investments and the inordinate devotion of scientists, engineers, managers, medical personnel and regulatory officials working in concert and around the clock.”

In the paper

“A sufficiently long tail (100–150 bp) is necessary to interact with poly(A) binding proteins that form complexes necessary for initiating translation11,12 and protecting the cap from degradation by decapping enzymes13.”

What the sources say

• Not checked yetcites [11] Linares-Fernández, S., Lacroix, C., Exposito, J. Y. & Verrier, B. Tailoring mRNA vaccine to balance innate/adaptive immune response. Trends Mol. Med. 26, 311–323 (2020). source
• Not checked yetcites [12] Xiong, Q., Lee, G. Y., Ding, J., Li, W. & Shi, J. Biomedical applications of mRNA nanomedicine. Nano Res. 11, 5281–5309 (2018). source
• Not checked yetcites [13] Mugridge, J. S., Coller, J. & Gross, J. D. Structural and molecular mechanisms for the control of eukaryotic 5′–3′ mRNA decay. Nat. Struct. Mol. Biol. 25, 1077–1085 (2018). source

In the paper

“TLR7 and TLR8 receptors bind to guanosine- or uridine-rich regions in mRNA and trigger the production of type I interferons, such as IFNα, that can block mRNA translation24.”

What the sources say

• Not checked yetcites [24] Vaidyanathan, S. et al. Uridine depletion and chemical modification increase Cas9 mRNA activity and reduce immunogenicity without HPLC purification. Mol. Ther. Nucleic Acids 12, 530–542 (2018). source

In the paper

“Although the open reading frame is not as malleable as the non-coding regions, it can be optimized to increase translation without altering the protein sequence by replacing rarely used codons with more frequently occurring codons that encode the same amino acid residue.”

In the paper

“Furthermore, they minimize regions that prevent ribosomes from scanning the mRNA transcript, such as sequences with secondary and tertiary structure (for example, hairpins) in the 5′ UTR20.”

What the sources say

• Not checked yetcites [20] Leppek, K., Das, R. & Barna, M. Functional 5′ UTR mRNA structures in eukaryotic translation regulation and how to find them. Nat. Rev. Mol. Cell Biol. 19, 158–174 (2018). source

In the paper

“The use of modified nucleosides, particularly modified uridine, prevents recognition by pattern recognition receptors, enabling sufficient levels of translation to produce prophylactic amounts of protein5.”

What the sources say

• Not checked yetcites [5] Pardi, N., Hogan, M. J., Porter, F. W. & Weissman, D. mRNA vaccines — a new era in vaccinology. Nat. Rev. Drug Discov. 17, 261–279 (2018). source

In the paper

“Moreover, the mumps vaccine, which was then the fastest developed vaccine, required 4 years from conception to approval (see Related links).”

In the paper

“The length of the poly(A) tail indirectly regulates both mRNA translation and half-life.”

In the paper

“These engineered UTR sequences minimize mRNA degradation by excluding miRNA-binding sites11 and AU-rich regions in the 3′ UTR19.”

What the sources say

• Not checked yetcites [11] Linares-Fernández, S., Lacroix, C., Exposito, J. Y. & Verrier, B. Tailoring mRNA vaccine to balance innate/adaptive immune response. Trends Mol. Med. 26, 311–323 (2020). source
• Not checked yetcites [19] Chen, C. Y. A. & Shyu, A. B. AU-rich elements: characterization and importance in mRNA degradation. Trends Biochem. Sci. 20, 465–470 (1995). source

In the paper

“The virus-derived polymerase amplifies mRNA transcripts intracellularly, enabling the expression of large amounts of antigen with reduced mRNA doses9.”

What the sources say

• Not checked yetcites [9] Bloom, K., van den Berg, F. & Arbuthnot, P. Self-amplifying RNA vaccines for infectious diseases. Gene Ther. 28, 117–129 (2021). source

In the paper

“Naturally occurring UTRs from highly expressed genes, such as the α- and β-globin genes, are preferred for synthetic mRNAs15.”

What the sources say

• Not checked yetcites [15] Weng, Y. et al. The challenge and prospect of mRNA therapeutics landscape. Biotechnol. Adv. 40, 107534 (2020). source

In the paper

“The 5′ and 3′ UTRs flanking the coding region regulate mRNA translation, half-life and subcellular localization10,14.”

What the sources say

• Not checked yetcites [10] Wadhwa, A., Aljabbari, A., Lokras, A., Foged, C. & Thakur, A. Opportunities and challenges in the delivery of mRNA-based vaccines. Pharmaceutics 12, 102 (2020). source
• Not checked yetcites [14] Berkovits, B. D. & Mayr, C. Alternative 3′ UTRs act as scaffolds to regulate membrane protein localization. Nature 522, 363–367 (2015). source

In the paper

“To maximize translation, the mRNA sequence typically incorporates modified nucleosides, such as pseudouridine, N1-methylpseudouridine or other nucleoside analogues23.”

What the sources say

• Not checked yetcites [23] Hajj, K. A. & Whitehead, K. A. Tools for translation: non-viral materials for therapeutic mRNA delivery. Nat. Rev. Mater. 2, 17056 (2017). source

In the paper

“1.7–4.6-fold higher neutralizing titres than convalescent serum in 18–55-year old participants”

What the sources say

• Not checked yetcites [124] Walsh, E. E. et al. Safety and immunogenicity of two RNA-based covid-19 vaccine candidates. N. Engl. J. Med. 383, 2439–2450 (2020). source

In the paper

“47% efficacy in phase III trials (see Related links)”

In the paper

“Because mRNA is large (104–106 Da) and negatively charged, it cannot pass through the anionic lipid bilayer of cell membranes.”

In the paper

“Most SARS-CoV-2 vaccine candidates induce an immune response to the spike protein on the virus surface (Fig. 4).”

In the paper

“All mRNA delivery vehicles contain cationic or ionizable molecules.”

In the paper

“A solution to overcome this stability issue is to include a short UGC linker in the poly(A) tail30,31.”

What the sources say

• Not checked yetcites [30] Stadler, C. R. et al. Elimination of large tumors in mice by mRNA-encoded bispecific antibodies. Nat. Med. 23, 815–817 (2017). source
• Not checked yetcites [31] Eberle, F., Sahin, U., Kuhn, A., Vallazza, B. & Diken, M. Stabilization of poly(A) sequence encoding Dna sequences. US 2017/0166905 A1 (2017).

In the paper

“Another strategy to avoid detection by pattern recognition receptors, pioneered by CureVac, uses sequence engineering and codon optimization to deplete uridines by boosting the GC content of the vaccine mRNA26.”

What the sources say

• Not checked yetcites [26] Thess, A. et al. Sequence-engineered mRNA without chemical nucleoside modifications enables an effective protein therapy in large animals. Mol. Ther. 23, 1456–1464 (2015). source

In the paper

“The Pfizer–BioNTech vaccine BNT162b2 against SARS-CoV-2 uses this strategy and contains a 10 bp UGC linker to produce the sequence A30(10 bp UGC linker)A70 (see the mRNA sequence in Related links).”

In the paper

“Incorporating the poly(A) tail in the DNA plasmid also overcomes the tail length variability that arises from enzymatic polyadenylation using poly(A) polymerase.”

In the paper

“94.1% overall efficacy in phase III trials131”

What the sources say

• Not checked yetcites [131] Baden, L. R. et al. Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine. N. Engl. J. Med. 384, 403–416 (2020). source

In the paper

“Surface proteins that enable cell entry are commonly used by mRNA vaccines to target viruses, for example, spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), haemagglutinin protein of influenza viruses, membrane and envelope protein (prM-E) of Zika virus, fusion protein of respiratory syncytial virus (RSV) and surface glycoproteins of human immunodeficiency virus (HIV),”

In the paper

“Both the Moderna and Pfizer–BioNTech SARS-CoV-2 vaccines, which produced >94% efficacy in phase III clinical trials25, contain nucleoside-modified mRNAs.”

What the sources say

• Not checked yetcites [25] Buschmann, M. D. et al. Nanomaterial delivery systems for mRNA vaccines. Vaccines 9, 65 (2021). source

In the paper

“95% overall efficacy in phase III trials125”

What the sources say

• Not checked yetcites [125] Polack, F. P. et al. Safety and efficacy of the BNT162b2 mRNA Covid-19 vaccine. N. Engl. J. Med. 383, 2603–2615 (2020). source

In the paper

“dose-dependent increase in S2-P-binding antibodies and serum-neutralizing titres in phase I trials130”

What the sources say

• Not checked yetcites [130] Jackson, L. A. et al. An mRNA vaccine against SARS-CoV-2 — preliminary report. N. Engl. J. Med. 383, 1920–1931 (2020). source

In the paper

“90–100% efficacy in phase III trials across subgroups defined by age, sex, race, ethnicity, baseline body mass index and the presence of coexisting conditions125”

What the sources say

• Not checked yetcites [125] Polack, F. P. et al. Safety and efficacy of the BNT162b2 mRNA Covid-19 vaccine. N. Engl. J. Med. 383, 2603–2615 (2020). source

In the paper

“Additionally, complex pathogens such as Plasmodium can be targeted using non-surface antigens such as Plasmodium macrophage migratory inhibiting factor (PMIF) or Plasmodium falciparum glutamic-acid-rich protein (PfGARP).”

In the paper

“1.1–2.2-fold higher titres in 65–85-year old in phase I trials124”

What the sources say

• Not checked yetcites [124] Walsh, E. E. et al. Safety and immunogenicity of two RNA-based covid-19 vaccine candidates. N. Engl. J. Med. 383, 2439–2450 (2020). source

In the paper

“The spike protein binds to its receptor on the host cell surface, angiotensin-converting enzyme 2 (ref.118).”

What the sources say

• Not checked yetcites [118] Shang, J. et al. Cell entry mechanisms of SARS-CoV-2. Proc. Natl Acad. Sci. USA 117, 11727–11734 (2020). This study describes the cell-entry mechanism of SARS-CoV-2. source

In the paper

“>90% efficacy in real-world conditions in USA132 and Israel126”

What the sources say

• Not checked yetcites [132] Thompson, M. G. et al. Interim estimates of vaccine effectiveness of BNT162b2 and mRNA-1273 COVID-19 vaccines in preventing SARS-CoV-2 infection among health care personnel, first responders, and other essential and frontline workers — eight U.S. locations, December 2020–March 2021. Morb. Mortal. Wkly Rep. 70, 495–500 (2021). source
• Not checked yetcites [126] Dagan, N. et al. BNT162b2 mRNA Covid-19 vaccine in a nationwide mass vaccination setting. N. Engl. J. Med. 384, 1412–1423 (2021). source

In the paper

“Of those in clinical trials, 19 were mRNA vaccines (Table 2).”

In the paper

“In vivo application, however, requires the use of mRNA delivery vehicles that transfect immune cells without causing toxicity or unwanted immunogenicity (Fig. 2).”

In the paper

“The two lead candidates, BNT162b1 and BNT162b2, use LNPs that are formulated using Acuitas Therapeutics’ ionizable lipid ALC-0315 and a nucleoside-modified mRNA in which all uridines are replaced by N1-methylpseudouridine to enhance mRNA translation.”

What the sources say

• Not checked yetcites [119] Knezevic, I., Liu, M. A., Peden, K., Zhou, T. & Kang, H.-N. Development of mRNA vaccines: scientific and regulatory issues. Vaccines 9, 81 (2021). source

In the paper

“Vaccinated macaques also elicited spike protein-specific IgG and IgA antibodies in nasal washes and bronchoalveolar lavages, suggesting that intramuscular vaccination with mRNA-1273 confers both serum and mucosal immunity128,129.”

What the sources say

• Not checked yetcites [128] Corbett, K. S. et al. Evaluation of the mRNA-1273 vaccine against SARS-CoV-2 in nonhuman primates. N. Engl. J. Med. 383, 1544–1555 (2020). source
• Not checked yetcites [129] Corbett, K. S. et al. Immune correlates of protection by mRNA-1273 vaccine against SARS-CoV-2 in nonhuman primates. Science eabj0299 (2021).

In the paper

“BNT162b1 encodes a trimerized, secreted version of the spike protein’s receptor-binding domain, whereas BNT162b2 encodes the full-length SARS-CoV-2 spike glycoprotein with two proline substitutions in the S2 subunit, which lock the protein in its prefusion conformation120,121.”

What the sources say

• Not checked yetcites [120] Wrapp, D. et al. Cryo-EM structure of the 2019-nCoV spike in the prefusion conformation. Science 367, 1260–1263 (2020). source
• Not checked yetcites [121] Walls, A. C. et al. Structure, function, and antigenicity of the SARS-CoV-2 Spike glycoprotein. Cell 181, 281–292.e6 (2020). source

In the paper

“It also protected the animals from upper and lower airway SARS-CoV-2 infection for at least 3 months after vaccination127.”

What the sources say

• Not checked yetcites [127] Corbett, K. S. et al. SARS-CoV-2 mRNA vaccine design enabled by prototype pathogen preparedness. Nature 586, 567–571 (2020). This study reports the development process of mRNA-1273. source

In the paper

“In real-world conditions involving 3,950 healthcare personnel, first responders and other essential and frontline workers in the USA, two doses of mRNA-1273 or BNT162b2 were 90% effective against SARS-CoV-2 (ref.132).”

What the sources say

• Not checked yetcites [132] Thompson, M. G. et al. Interim estimates of vaccine effectiveness of BNT162b2 and mRNA-1273 COVID-19 vaccines in preventing SARS-CoV-2 infection among health care personnel, first responders, and other essential and frontline workers — eight U.S. locations, December 2020–March 2021. Morb. Mortal. Wkly Rep. 70, 495–500 (2021). source

In the paper

“In phase I trials of the two candidates, two 30 μg doses delivered 21 days apart induced high antibody and neutralizing titres and a robust CD4+ and CD8+ response with mild to moderate adverse events27,28,123,124.”

What the sources say

• Not checked yetcites [27] Sahin, U. et al. COVID-19 vaccine BNT162b1 elicits human antibody and TH1 T cell responses. Nature 586, 594–599 (2020). source
• Not checked yetcites [28] Sahin, U. et al. BNT162b2 vaccine induces neutralizing antibodies and poly-specific T cells in humans. Nature 595, 572–577 (2021). source
• Not checked yetcites [123] Mulligan, M. J. et al. Phase I/II study of COVID-19 RNA vaccine BNT162b1 in adults. Nature 586, 589–593 (2020). source
• Not checked yetcites [124] Walsh, E. E. et al. Safety and immunogenicity of two RNA-based covid-19 vaccine candidates. N. Engl. J. Med. 383, 2439–2450 (2020). source

In the paper

“In a preclinical trial, two 1 μg doses of vaccine (a primer dose and a booster) injected into muscle induced robust virus-neutralizing activity as well as potent CD4+ and CD8+ T cell responses in mice127.”

What the sources say

• Not checked yetcites [127] Corbett, K. S. et al. SARS-CoV-2 mRNA vaccine design enabled by prototype pathogen preparedness. Nature 586, 567–571 (2020). This study reports the development process of mRNA-1273. source

In the paper

“After the second dose, half of the volunteers reported moderate-to-severe systemic side effects (for example, fatigue, muscle pain, joint pain) that resolved within 48 h131.”

What the sources say

• Not checked yetcites [131] Baden, L. R. et al. Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine. N. Engl. J. Med. 384, 403–416 (2020). source

In the paper

“suggesting that intramuscular vaccination with mRNA-1273 confers both serum and mucosal immunity128,129.”

What the sources say

• Not checked yetcites [128] Corbett, K. S. et al. Evaluation of the mRNA-1273 vaccine against SARS-CoV-2 in nonhuman primates. N. Engl. J. Med. 383, 1544–1555 (2020). source
• Not checked yetcites [129] Corbett, K. S. et al. Immune correlates of protection by mRNA-1273 vaccine against SARS-CoV-2 in nonhuman primates. Science eabj0299 (2021).

In the paper

“In phase III trials involving 30,420 volunteers, two 100 μg vaccine doses were 94.1% effective at preventing the onset of COVID-19 (ref.131).”

What the sources say

• Not checked yetcites [131] Baden, L. R. et al. Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine. N. Engl. J. Med. 384, 403–416 (2020). source

In the paper

“1.9–4.6-fold higher neutralization titres than convalescent serum27,123”

What the sources say

• Not checked yetcites [27] Sahin, U. et al. COVID-19 vaccine BNT162b1 elicits human antibody and TH1 T cell responses. Nature 586, 594–599 (2020). source
• Not checked yetcites [123] Mulligan, M. J. et al. Phase I/II study of COVID-19 RNA vaccine BNT162b1 in adults. Nature 586, 589–593 (2020). source

In the paper

“BNT162b1 encodes a trimerized, secreted version of the spike protein’s receptor-binding domain, whereas BNT162b2 encodes the full-length SARS-CoV-2 spike glycoprotein with two proline substitutions in the S2 subunit, which lock the protein in its prefusion conformation120,121.”

What the sources say

• Not checked yetcites [120] Wrapp, D. et al. Cryo-EM structure of the 2019-nCoV spike in the prefusion conformation. Science 367, 1260–1263 (2020). source
• Not checked yetcites [121] Walls, A. C. et al. Structure, function, and antigenicity of the SARS-CoV-2 Spike glycoprotein. Cell 181, 281–292.e6 (2020). source

In the paper

“8–50-fold higher anti-RBD IgG”

What the sources say

• Not checked yetcites [27] Sahin, U. et al. COVID-19 vaccine BNT162b1 elicits human antibody and TH1 T cell responses. Nature 586, 594–599 (2020). source
• Not checked yetcites [123] Mulligan, M. J. et al. Phase I/II study of COVID-19 RNA vaccine BNT162b1 in adults. Nature 586, 589–593 (2020). source

In the paper

“Pfizer and BioNTech co-developed five mRNA vaccine candidates that encode variants of the spike protein antigen119.”

What the sources say

• Not checked yetcites [119] Knezevic, I., Liu, M. A., Peden, K., Zhou, T. & Kang, H.-N. Development of mRNA vaccines: scientific and regulatory issues. Vaccines 9, 81 (2021). source

In the paper

“Approved in Japan based on positive interim phase I/II data (see Related links)”

In the paper

“Rhesus macaques that received two 100 μg doses of the vaccine also developed potent humoral and cellular immune responses128.”

What the sources say

• Not checked yetcites [128] Corbett, K. S. et al. Evaluation of the mRNA-1273 vaccine against SARS-CoV-2 in nonhuman primates. N. Engl. J. Med. 383, 1544–1555 (2020). source

In the paper

“One study showed that a single 30 µg or 50 µg dose of a LNP-encapsulated nucleoside-modified prM-E mRNA protected mice and rhesus macaques, respectively, from a Zika challenge153.”

What the sources say

• Not checked yetcites [153] Pardi, N. et al. Zika virus protection by a single low-dose nucleoside-modified mRNA vaccination. Nature 543, 248–251 (2017). source

In the paper

“In 2013, for example, a LNP (DLinDMA)-based self-amplifying mRNA vaccine was rapidly formulated within 8 days after the H7N9 outbreak in China140.”

What the sources say

• Not checked yetcites [140] Hekele, A. et al. Rapidly produced SAM® vaccine against H7N9 influenza is immunogenic in mice. Emerg. Microbes Infect. 2, e52 (2013). source

In the paper

“Both produced excellent seroconversion and seroprotection147.”

What the sources say

• Not checked yetcites [147] Bahl, K. et al. Preclinical and clinical demonstration of immunogenicity by mrna vaccines against H10N8 and H7N9 influenza viruses. Mol. Ther. 25, 1316–1327 (2017). source

In the paper

“Unfortunately, in phase IIb/III trials involving 40,000 participants and spanning ten countries, CVnCoV demonstrated 47% efficacy against COVID-19 (see Related links).”

What the sources say

• Not checked yetcites Related links

In the paper

“In mice, 10 ng primer and booster doses injected 28 days apart into muscle yielded a robust T cell response and IgG titres similar to those in plasma from patients who had recovered from COVID-19 (ref.136).”

What the sources say

• Not checked yetcites [136] McKay, P. F. et al. Self-amplifying RNA SARS-CoV-2 lipid nanoparticle vaccine candidate induces high neutralizing antibody titers in mice. Nat. Commun. 11, 3–9 (2020). source

In the paper

“A primer–booster regimen of a LNP-based mRNA vaccine (30 µg) encoding the conserved haemagglutinin stalk from the Cal09 H1N1 strain produced a stalk-specific antibody response in mice, ferrets and rabbits149.”

What the sources say

• Not checked yetcites [149] Pardi, N. et al. Nucleoside-modified mRNA immunization elicits influenza virus hemagglutinin stalk-specific antibodies. Nat. Commun. 9, 3361 (2018). source

In the paper

“Fortunately, all Zika infections are caused by a single serotype, suggesting that vaccinating against an antigen from any strain could protect against all Zika strains152.”

What the sources say

• Not checked yetcites [152] Dowd, K. A. et al. Broadly neutralizing activity of zika virus-immune sera identifies a single viral serotype. Cell Rep. 16, 1485–1491 (2016). source

In the paper

“At the time of writing, CureVac, in collaboration with GSK, is developing a second-generation candidate — CV2CoV — that has been optimized to enhance translation and immunogenicity relative to CVnCoV.”

What the sources say

• Not checked yetcites [134] Roth, N. et al. CV2CoV, an enhanced mRNA-based SARS-CoV-2 vaccine candidate, supports higher protein expression and improved immunogenicity in rats. bioRxiv, https://www.biorxiv.org/content/10.1101/2021.05.13.443734v1.full (2021).

In the paper

“For example, loss of a glycosylation site in egg-grown vaccines was associated with poor efficacy during the 2016–2017 season139.”

What the sources say

• Not checked yetcites [139] Zost, S. J. et al. Contemporary H3N2 influenza viruses have a glycosylation site that alters binding of antibodies elicited by egg-adapted vaccine strains. Proc. Natl Acad. Sci. USA 114, 12578–12583 (2017). source

In the paper

“Fortunately, all Zika infections are caused by a single serotype, suggesting that vaccinating against an antigen from any strain could protect against all Zika strains152.”

What the sources say

• Not checked yetcites [152] Dowd, K. A. et al. Broadly neutralizing activity of zika virus-immune sera identifies a single viral serotype. Cell Rep. 16, 1485–1491 (2016). source

In the paper

“In preclinical studies, two 10 μg doses in mice and two 100 μg doses in cynomolgus monkeys delivered 21 days apart elicited high SARS-CoV-2-specific IgG antibodies and strong virus neutralization titres135.”

What the sources say

• Not checked yetcites [135] Zhang, N. N. et al. A thermostable mRNA vaccine against COVID-19. Cell 182, 1271–1283.e16 (2020). source

In the paper

“Interestingly, these results suggest that mRNA therapeutics encoding neutralizing mAbs may have both prophylactic and therapeutic activity.”

What the sources say

• Not checked yetcites [157] Erasmus, J. H. et al. Intramuscular delivery of replicon RNA encoding ZIKV-117 human monoclonal antibody protects against Zika virus. Infect. Mol. Ther. Methods Clin. Dev. 18, 402–414 (2020). source
• Not checked yetcites [158] Kose, N. et al. A lipid-encapsulated mRNA encoding a potently neutralizing human monoclonal antibody protects against Chikungunya infection. Sci. Immunol. 4, 6647 (2019). source

In the paper

“These studies suggest that novel antigens are necessary to effectively target HIV in addition to potent delivery vehicles.”

What the sources say

• Not checked yetcites [109] Brito, L. A. et al. A cationic nanoemulsion for the delivery of next-generation RNA vaccines. Mol. Ther. 22, 2118–2129 (2014). source
• Not checked yetcites [161] Bogers, W. M. et al. Potent immune responses in rhesus macaques induced by nonviral delivery of a self-amplifying RNA vaccine expressing HIV type 1 envelope with a cationic nanoemulsion. J. Infect. Dis. 211, 947–955 (2015). source
• Not checked yetcites [162] Pollard, C. et al. Type I IFN counteracts the induction of antigen-specific immune responses by lipid-based delivery of mRNA vaccines. Mol. Ther. 21, 251–259 (2013). source
• Not checked yetcites [84] Li, M. et al. Enhanced intranasal delivery of mRNA vaccine by overcoming the nasal epithelial barrier via intra- and paracellular pathways. J. Control. Rel. 228, 9–19 (2016). source
• Not checked yetcites [163] Moyo, N. et al. Efficient induction of T cells against conserved HIV-1 regions by mosaic vaccines delivered as self-amplifying mRNA. Mol. Ther. Methods Clin. Dev. 12, 32–46 (2019). source
• Not checked yetcites [164] Zhao, M., Li, M., Zhang, Z., Gong, T. & Sun, X. Induction of HIV-1 gag specific immune responses by cationic micelles mediated delivery of gag mRNA. Drug Deliv. 23, 2596–2607 (2016). source
• Not checked yetcites [165] Blakney, A. K., McKay, P. F., Yus, B. I., Aldon, Y. & Shattock, R. J. Inside out: optimization of lipid nanoparticle formulations for exterior complexation and in vivo delivery of saRNA. Gene Ther. 26, 363–372 (2019). source
• Not checked yetcites [166] Pardi, N. et al. Characterization of HIV-1 nucleoside-modified mRNA vaccines in rabbits and rhesus macaques. Mol. Ther. Nucleic Acids 15, 36–47 (2019). source

In the paper

“Importantly, a single dose protected mice from intravenous challenge with HIV-1.”

What the sources say

• Not checked yetcites [169] Pardi, N. et al. Administration of nucleoside-modified mRNA encoding broadly neutralizing antibody protects humanized mice from HIV-1 challenge. Nat. Commun. 8, 6–13 (2017). source

In the paper

“In one study, a single 0.7 mg kg−1 intravenous injection of a LNP-encapsulated, nucleoside-modified mRNA expressing VRC01, produced similar antibody concentrations to those typically achieved by injecting a 10–20 mg kg−1 dose of mAb protein169.”

What the sources say

• Not checked yetcites [169] Pardi, N. et al. Administration of nucleoside-modified mRNA encoding broadly neutralizing antibody protects humanized mice from HIV-1 challenge. Nat. Commun. 8, 6–13 (2017). source

In the paper

“A single 40 µg dose delivered either a day before or a day after viral inoculation protected immunocompromised mice from the lethal viral challenge157.”

What the sources say

• Not checked yetcites [157] Erasmus, J. H. et al. Intramuscular delivery of replicon RNA encoding ZIKV-117 human monoclonal antibody protects against Zika virus. Infect. Mol. Ther. Methods Clin. Dev. 18, 402–414 (2020). source

In the paper

“Although rVSV-EBOV is 97.5% effective at preventing Ebola transmission compared with no vaccination (see Related links), clinical trials note some safety concerns (for example, acute arthritis and skin rash at high doses)183.”

What the sources say

• Not checked yetcites Related links

In the paper

“One mRNA vaccine has demonstrated efficacy in mice upon delivery of an unmodified, self-amplifying mRNA encoding the EBOV glycoprotein (Fig. 4) in a poly(amidoamine) dendrimer nanoparticle.”

What the sources say

• Not checked yetcites [184] Chahal, J. S. et al. Dendrimer-RNA nanoparticles generate protective immunity against lethal Ebola, H1N1 influenza, and Toxoplasma gondii challenges with a single dose. Proc. Natl Acad. Sci. USA 113, E5250 (2016). source

In the paper

“mRNA vaccines against EBOV are likely safer than this virus-based vaccine because they do not replicate inside the body.”

In the paper

“Moreover, adoptive transfer of T cells from vaccinated mice protected unvaccinated mice from Plasmodium sporozoites192.”

What the sources say

• Not checked yetcites [192] Baeza Garcia, A. et al. Neutralization of the Plasmodium-encoded MIF ortholog confers protective immunity against malaria infection. Nat. Commun. 9, 2714 (2018). source

In the paper

“Interim phase I data suggest that a 100 μg dose of mRNA-1345 produces approximately eightfold higher neutralizing antibody titres than mRNA-1777 1 month after vaccination (see Related links).”

What the sources say

• Not checked yetcites Related links

In the paper

“In preclinical studies, mRNA vaccines encoding either the native RSV F protein or the stabilized prefusion conformation were successfully delivered using cationic nanoemulsions109 and LNPs179,180 without any observed instances of VAED.”

What the sources say

• Not checked yetcites [109] Brito, L. A. et al. A cationic nanoemulsion for the delivery of next-generation RNA vaccines. Mol. Ther. 22, 2118–2129 (2014). source
• Not checked yetcites [179] Espeseth, A. S. et al. Modified mRNA/lipid nanoparticle-based vaccines expressing respiratory syncytial virus F protein variants are immunogenic and protective in rodent models of RSV infection. NPJ Vaccines 5, 1–14 (2020). source
• Not checked yetcites [180] Geall, A. J. et al. Nonviral delivery of self-amplifying RNA vaccines. Proc. Natl Acad. Sci. USA 109, 14604–14609 (2012). source

In the paper

“For example, the Plasmodium-secreted cytokine, macrophage migrating inhibitory factor (PMIF), has been shown to prevent T cells from developing long-term memory191.”

What the sources say

• Not checked yetcites [191] Sun, T. et al. A Plasmodium-encoded cytokine suppresses T-cell immunity during malaria. Proc. Natl Acad. Sci. USA 109, E2117 (2012). source

In the paper

“However, cross-neutralization efficacies have been significantly lower compared with the ancestral variant208–211.”

What the sources say

• Not checked yetcites [208] Wang, Z. et al. mRNA vaccine-elicited antibodies to SARS-CoV-2 and circulating variants. Nature 592, 616–622 (2021). source
• Not checked yetcites [209] Liu, Y. et al. Neutralizing activity of BNT162b2-elicited serum. N. Engl. J. Med. 384, 1466–1468 (2021). source
• Not checked yetcites [210] Wu, K. et al. Serum neutralizing activity elicited by mRNA-1273 vaccine. N. Engl. J. Med. 384, 1468–1470 (2021). source
• Not checked yetcites [211] Pegu, A. et al. Durability of mRNA-1273 vaccine–induced antibodies against SARS-CoV-2 variants. Science 12, eabj4176 (2021).

In the paper

“Saunders and colleagues212 have shown that nucleoside-modified mRNA–LNP vaccines encoding the SARS-CoV-2 spike protein can elicit SARS-CoV-1 and batCoV cross-neutralizing antibodies.”

What the sources say

• Not checked yetcites [212] Saunders, K. O. et al. Neutralizing antibody vaccine for pandemic and pre-emergent coronaviruses. Nature 594, 553–559 (2021). This study suggests that mRNA vaccines can be used as a platform to develop pancoronavirus vaccines. source

In the paper

“In humans, two doses of the Pfizer–BioNTech vaccine BNT162b2 induced strong germinal centre B cell responses for at least 12 weeks after immunization203.”

What the sources say

• Not checked yetcites [203] Turner, J. S. et al. SARS-CoV-2 mRNA vaccines induce robust plasmablast and germinal centre responses in humans. Nature https://doi.org/10.1038/s41586-021-03738-2 (2021). source

In the paper

“Sustained antigen availability during the germinal centre reaction has been shown to increase antibody production by approximately tenfold199.”

What the sources say

• Not checked yetcites [199] Tam, H. H. et al. Sustained antigen availability during germinal center initiation enhances antibody responses to vaccination. Proc. Natl Acad. Sci. USA 113, E6639–E6648 (2016). source

In the paper

“The B.1.351 and P.1 variants have a glutamate (E) to lysine (K) mutation at position 484 (E484K) in the receptor-binding domain of the spike protein, which promotes immune evasion207.”

What the sources say

• Not checked yetcites [207] Yuan, M. et al. Structural and functional ramifications of antigenic drift in recent SARS-CoV-2 variants. Science https://doi.org/10.1101/2021.02.16.430500 (2021). source

In the paper

“Fortunately, the FDA-approved mRNA vaccines BNT162b2 and mRNA-1273 produce cross-neutralizing antibodies against B.1.351 and P.1, as well as against other variants, suggesting that they can provide protection against them.”

What the sources say

• Not checked yetcites [208] Wang, Z. et al. mRNA vaccine-elicited antibodies to SARS-CoV-2 and circulating variants. Nature 592, 616–622 (2021). source
• Not checked yetcites [209] Liu, Y. et al. Neutralizing activity of BNT162b2-elicited serum. N. Engl. J. Med. 384, 1466–1468 (2021). source
• Not checked yetcites [210] Wu, K. et al. Serum neutralizing activity elicited by mRNA-1273 vaccine. N. Engl. J. Med. 384, 1468–1470 (2021). source
• Not checked yetcites [211] Pegu, A. et al. Durability of mRNA-1273 vaccine–induced antibodies against SARS-CoV-2 variants. Science 12, eabj4176 (2021).

In the paper

“Furthermore, the germinal centre responses after mRNA vaccination were superior to those seen after the seasonal influenza vaccination in humans204.”

What the sources say

• Not checked yetcites [204] Turner, J. S. et al. Human germinal centres engage memory and naive B cells after influenza vaccination. Nature 586, 127–132 (2020). source

In the paper

“in phase IIb/III trials of CureVac’s candidate CVnCoV, 57% of the sequenced 124 COVID-19 cases were attributed to variants of concern, which include the B.1.351 and P.1 variants (see Related links).”

What the sources say

• Not checked yetcites Related links

In the paper

“If these variants of concern emerge as the dominant variant over time, variant-specific mRNA boosters may be required.”

In the paper

“Fortunately, the FDA-approved mRNA vaccines BNT162b2 and mRNA-1273 produce cross-neutralizing antibodies against B.1.351 and P.1, as well as against other variants, suggesting that they can provide protection against them.”

In the paper

“In several studies, maternal vaccination with mRNA-loaded LNPs prevented fetal Zika virus transmission in pregnant mice225,226 and protected mouse neonates from herpesvirus227 and group A and group B streptococci228.”

What the sources say

• Not checked yetcites [225] Richner, J. M. et al. Vaccine mediated protection against Zika virus-induced congenital disease. Cell 170, 273–283.e12 (2017). source
• Not checked yetcites [226] Jagger, B. W. et al. Protective efficacy of nucleic acid vaccines against transmission of Zika virus during pregnancy in mice. J. Infect. Dis. 220, 1577–1588 (2019). source

In the paper

“CureVac’s protamine-based rabies candidate CV7201 elicited severe adverse events in 78% of participants188”

What the sources say

• Not checked yetcites [188] Alberer, M. et al. Safety and immunogenicity of a mRNA rabies vaccine in healthy adults: an open-label, non-randomised, prospective, first-in-human phase 1 clinical trial. Lancet 390, 1511–1520 (2017). source

In the paper

“in phase I trials of CV7202, a 5 μg dose had unacceptable reactogenicity, and 1 μg was the highest dose that was well tolerated.”

What the sources say

• Not checked yetcites [189] Lutz, J. et al. Unmodified mRNA in LNPs constitutes a competitive technology for prophylactic vaccines. NPJ Vaccines 2, 29 (2017). source

In the paper

“in phase I trials of the Moderna influenza H10N8 vaccine, severe adverse events from the 400 μg dose stopped further evaluation of that dose150.”

What the sources say

• Not checked yetcites [150] Feldman, R. A. et al. mRNA vaccines against H10N8 and H7N9 influenza viruses of pandemic potential are immunogenic and well tolerated in healthy adults in phase 1 randomized clinical trials. Vaccine 37, 3326–3334 (2019). source

In the paper

“The dynamic nature of the immune system during pregnancy increases a person’s susceptibility to infectious diseases, and infection can have disastrous impacts on maternal health and fetal development219.”

What the sources say

• Not checked yetcites [219] Vermillion, M. S. & Klein, S. L. Pregnancy and infection: using disease pathogenesis to inform vaccine strategy. NPJ Vaccines 3, 6 (2018). source

In the paper

“The dynamic nature of the immune system during pregnancy increases a person’s susceptibility to infectious diseases, and infection can have disastrous impacts on maternal health and fetal development219.”

What the sources say

• Not checked yetcites [219] Vermillion, M. S. & Klein, S. L. Pregnancy and infection: using disease pathogenesis to inform vaccine strategy. NPJ Vaccines 3, 6 (2018). source

In the paper

“As with most drugs, adverse reactions to mRNA vaccines have often increased with dose.”

In the paper

“In preclinical studies, the presence of anti-PEG IgM in animal serum accelerated nanoparticle clearance and caused a complete loss of the efficacy of mRNA therapeutics217,218.”

What the sources say

• Not checked yetcites [217] Abu Lila, A. S., Kiwada, H. & Ishida, T. The accelerated blood clearance (ABC) phenomenon: clinical challenge and approaches to manage. J. Control. Rel. 172, 38–47 (2013). source
• Not checked yetcites [218] Kozma, G. T., Shimizu, T., Ishida, T. & Szebeni, J. Anti-PEG antibodies: properties, formation, testing and role in adverse immune reactions to PEGylated nano-biopharmaceuticals. Adv. Drug Deliv. Rev. 154–155, 163–175 (2020). source

In the paper

“prompting CureVac to adopt LNPs as their preferred delivery platform for their subsequent rabies candidate CV7202 (ref.189).”

What the sources say

• Not checked yetcites [189] Lutz, J. et al. Unmodified mRNA in LNPs constitutes a competitive technology for prophylactic vaccines. NPJ Vaccines 2, 29 (2017). source

In the paper

“in phase I trials of CV7202, a 5 μg dose had unacceptable reactogenicity, and 1 μg was the highest dose that was well tolerated.”

What the sources say

• Not checked yetcites [189] Lutz, J. et al. Unmodified mRNA in LNPs constitutes a competitive technology for prophylactic vaccines. NPJ Vaccines 2, 29 (2017). source

In the paper

“Anaphylactic reactions have been observed in approximately 4.7 per million anti-COVID-19 vaccinations with the Pfizer–BioNTech vaccine and 2.5 per million vaccinations with the Moderna vaccine213”

What the sources say

• Not checked yetcites [213] Shimabukuro, T. T., Cole, M. & Su, J. R. Reports of anaphylaxis after receipt of mRNA COVID-19 vaccines in the US — December 14, 2020-January 18, 2021. JAMA 325, 1101–1102 (2021). source