CoChat
Sign Up
Cited by 1,747SARS-CoV-2 and COVID-19 ResearchCOVID-19 Clinical Research StudiesVirus-based gene therapy research

Safety and efficacy of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine: an interim analysis of a randomised controlled phase 3 trial in Russia

Open access
Logunov, Denis Y, Dolzhikova, Inna V, Shcheblyakov, Dmitry V, Tukhvatulin, Amir I, Zubkova, Olga V, Dzharullaeva, Alina S, Kovyrshina, Anna V, Lubenets, Nadezhda L +23 more·2021·The Lancet
DOI 10.1016/s0140-6736(21)00234-8PMC PMC7852454
Open this paper in CoChat — free accountOpen PDF

Abstract

Background A heterologous recombinant adenovirus (rAd)-based vaccine, Gam-COVID-Vac (Sputnik V), showed a good safety profile and induced strong humoral and cellular immune responses in participants in phase 1/2 clinical trials. Here, we report preliminary results on the efficacy and safety of Gam-COVID-Vac from the interim analysis of this phase 3 trial. Methods We did a randomised, double-blind, placebo-controlled, phase 3 trial at 25 hospitals and polyclinics in Moscow, Russia. We included participants aged at least 18 years, with negative SARS-CoV-2 PCR and IgG and IgM tests, no infectious diseases in the 14 days before enrolment, and no other vaccinations in the 30 days before enrolment. Participants were randomly assigned (3:1) to receive vaccine or placebo, with stratification by age group. Investigators, participants, and all study staff were masked to group assignment. The vaccine was administered (0·5 mL/dose) intramuscularly in a prime-boost regimen: a 21-day interval between the first dose (rAd26) and the second dose (rAd5), both vectors carrying the gene for the full-length SARS-CoV-2 glycoprotein S. The primary outcome was the proportion of participants with PCR-confirmed COVID-19 from day 21 after receiving the first dose. All analyses excluded participants with protocol violations: the primary outcome was assessed in participants who had received two doses of vaccine or placebo, serious adverse events were assessed in all participants who had received at least one dose at the time of database lock, and rare adverse events were assessed in all participants who had received two doses and for whom all available data were verified in the case report form at the time of database lock. The trial is registered at ClinicalTrials.gov (NCT04530396). Findings Between Sept 7 and Nov 24, 2020, 21 977 adults were randomly assigned to the vaccine group (n=16 501) or the placebo group (n=5476). 19 866 received two doses of vaccine or placebo and were included in the primary outcome analysis. From 21 days after the first dose of vaccine (the day of dose 2), 16 (0·1%) of 14 964 participants in the vaccine group and 62 (1·3%) of 4902 in the placebo group were confirmed to have COVID-19; vaccine efficacy was 91·6% (95% CI 85·6-95·2). Most reported adverse events were grade 1 (7485 [94·0%] of 7966 total events). 45 (0·3%) of 16 427 participants in the vaccine group and 23 (0·4%) of 5435 participants in the placebo group had serious adverse events; none were considered associated with vaccination, with confirmation from the independent data monitoring committee. Four deaths were reported during the study (three [<0·1%] of 16 427 participants in the vaccine group and one [<0·1%] of 5435 participants in the placebo group), none of which were considered related to the vaccine. Interpretation This interim analysis of the phase 3 trial of Gam-COVID-Vac showed 91·6% efficacy against COVID-19 and was well tolerated in a large cohort. Funding Moscow City Health Department, Russian Direct Investment Fund, and Sberbank.

Integrity signals

Registry

Crossref · 10.1016/s0140-6736(21)00234-8

Cites

Statistics

Nothing to recompute.

Claims the paper makes

0 of 20 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    At day 42, RBD-specific IgG was detected in 336 (98%) of 342 samples from the vaccine group.

    “In the vaccine group, RBD-specific IgG was detected in 336 (98%) of 342 samples, with a geometric mean titre (GMT) of 8996 (95% CI 7610–10 635), and a seroconversion rate of 98·25%.”
    Quote in the paperSubstantial claim
  • Findingown data

    The geometric mean titre of RBD-specific IgG in the vaccine group at day 42 was 8996 (95% CI 7610-10 635).

    “In the vaccine group, RBD-specific IgG was detected in 336 (98%) of 342 samples, with a geometric mean titre (GMT) of 8996 (95% CI 7610–10 635), and a seroconversion rate of 98·25%.”
    Quote in the paperSubstantial claim
  • Findingown data

    14,964 vaccine and 4,902 placebo participants had received two doses by database lock and were included in the primary outcome analysis.

    “14 964 in the vaccine group and 4902 in the placebo group had received two doses at the time of database lock (Nov 24, 2020) and were included in the primary outcome analysis (table 1 ).”
    Quote in the paperSubstantial claim
  • Findingown data

    By day 28 after first vaccination, all vaccine group participants had significantly higher IFN-γ secretion upon antigen restimulation (median 32.77 pg/mL [IQR 13.94-50.76]) than on the day of first dose.

    “By day 28 after first vaccination, all participants in the vaccine group had significantly higher levels of IFN-γ secretion upon antigen restimulation (median 32·77 pg/mL [IQR 13·94–50·76]) compared with the day of administration of the first dose (figure 4 ).”
    Quote in the paperSubstantial claim
  • Findingown data

    Most reported adverse events were grade 1, accounting for 7485 (94.0%) of 7966 total events.

    “Most reported adverse events were grade 1 (7485 [94·0%] of 7966 total events).”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. 20
  • May combine two claims. 33
  • The quote only partly states this claim. 1

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    Median time from first dose to database lock was 48 days (IQR 39-58).

    “Median time from participants receiving the first dose to the date of database lock was 48 days (IQR 39–58).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    The heterologous prime-boost regimen produced robust humoral and cellular immune responses.

    “The heterologous prime-boost regimen of vaccination provides robust humoral and cellular immune responses, with 91·6% (95% CI 85·6–95·2) efficacy against COVID-19.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In the vaccine group at day 42, the geometric mean titre of neutralising antibodies was 44.5 (95% CI 31.8-62.2) and the seroconversion level was 95.83%.

    “the GMT of neutralising antibodies was 44·5 (95% CI 31·8–62·2) and the seroconversion level was 95·83% in the vaccine group.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    RBD-specific antibody levels did not differ significantly between men and women (p=0.258).

    “Antibody levels did not differ significantly between men (n=179) and women (n=159; p=0·258).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    From 15 to 21 days after the first dose, efficacy was 73.6% (p=0.048), and from day 21 onward efficacy was 100% (p<0.0001).

    “From 15 to 21 days after the first dose, efficacy was 73·6% (p=0·048), then from day 21, efficacy was 100% (p<0·0001; appendix p 11).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In the placebo group, the neutralising antibody geometric mean titre was 1.6 (1.12-2.19) and the seroconversion rate was 7.14%, significantly lower than in the vaccine group (p<0.0001).

    “GMT in the placebo group was 1·6 (1·12–2·19) and the seroconversion rate was 7·14%, which was significantly lower than that in the vaccine group (p<0·0001).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Four deaths occurred: three (<0.1%) among 16,427 vaccine recipients and one (<0.1%) among 5,435 placebo recipients.

    “Four deaths were reported during the study (three [<0·1%] of 16 427 participants in the vaccine group and one [<0·1%] of 5435 participants in the placebo group)”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Ninety-seven confirmed COVID-19 cases occurred fewer than 21 days after dose 1 and were not included in the primary endpoint analysis.

    “97 confirmed cases of COVID-19 (63 in the vaccine group and 34 in the placebo group) are not reflected in the analysis of the primary endpoint because they occurred fewer than 21 days after dose 1 (ie, before dose 2; table 2, figure 2 ).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Neutralising antibody levels were similar between age strata (p=0.222) and between men and women (p=0.639).

    “Levels of neutralising antibodies were similar between age strata (p=0·222) and between men and women (p=0·639).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Disease onset rates were similar between vaccine and placebo groups until about 16-18 days after dose 1, after which cases in the vaccine group increased more slowly than in the placebo group.

    “Rates of disease onset were similar for the vaccine and placebo groups until about 16–18 days after dose 1, after which, early onset of protection led to the number of cases in the vaccine group increasing much more slowly than in the placebo group (figure 2).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    74 vaccine recipients and 41 placebo recipients were excluded from the analyses.

    “74 participants from the vaccine group and 41 from the placebo group were excluded from analyses (figure 1).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Before first vaccination, no RBD-specific antibodies or virus-neutralising antibodies were detected in the tested participants' blood serum.

    “Before first vaccination, no RBD-specific antibodies (of 456 participants tested) or virus-neutralising antibodies (of 100 participants tested) were detected in the blood serum of participants.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In the older-than-60 safety analysis, the most common adverse events were flu-like illness in 156 (15.2%) and local reaction in 56 (5.4%) of 1029 vaccine recipients, and 30 (8.8%) and four (1.2%) of 340 placebo recipients.

    “The most common adverse events were flu-like illness in 156 (15·2%) and local reaction in 56 (5·4%) of 1029 participants in the vaccine group and 30 (8·8%) and four (1·2%) of 340 participants in the placebo group (appendix p 11).”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    In participants older than 60 years, there were three episodes of grade 3 or worse adverse events considered not associated with vaccination: urolithiasis exacerbation and acute sinusitis in the vaccine group and flu-like illness in the placebo group; all resolved.

    “There were three episodes of adverse events of grade 3 or worse, considered not associated with vaccination: an exacerbation of urolithiasis and acute sinusitis in the vaccine group and a flu-like illness in the placebo group. All these adverse events were resolved.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    In the vaccine group, one death was associated with a thoracic vertebra fracture and two were associated with COVID-19.

    “In the vaccine group, one death was associated with fracture of the thoracic vertebra and the other two were associated with COVID-19 (one patient with a severe cardiovascular background who developed symptoms on day 4 after first dose and one patient with a background of endocrinological comorbidities who developed symptoms on day 5 after first dose; appendix p 12).”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Findingown data

    Four deaths were recorded: three (<0.1%) of 16,427 vaccine recipients and one (<0.1%) of 5,435 placebo recipients.

    “During the study, four deaths were recorded: three (<0·1%) of 16 427 participants in the vaccine group and one (<0·1%) of 5435 participants in the placebo group.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Findingown data

    Among seven placebo participants confirmed to have COVID-19 within the first 7 days after the first dose, there were no comorbid conditions, whereas in the vaccine group three of 25 confirmed cases had a comorbidity.

    “Among the seven participants assigned to the placebo group who were confirmed to have COVID-19 within the first 7 days after the first dose, there were no comorbid conditions, in contrast to the vaccine group, in which there were three participants with a comorbidity among 25 who were confirmed to have COVID-19 within the first 7 days.”
    Quote in the paperNot a substantial claim

  • May combine two claims. The quote only partly states this claim.

    Findingown data

    In participants older than 60 years, three serious adverse events were reported in the vaccine group: renal colic, deep vein thrombosis, and extremity abscess; no association was found between serious adverse events and vaccine administration.

    “adverse events reported in the vaccine group: renal colic and deep vein thrombosis (both associated with pre-existing comorbidities) and extremity abscess (due to physical injury and subsequent infection of the wound surface of the soft tissues of the finger). No association was found between serious adverse events and vaccine administration.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    The safety analysis, including rare adverse events, included all participants who had received two doses and whose available data were verified in the case report form at database lock.

    “The safety analysis (including rare adverse events) included all participants who had received two doses and for whom all available data were verified in the case report form at the time of database lock.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    Two immunisations produce a durable and long-lasting immune response.

    “Furthermore, the use of two immunisations gives a durable and long-lasting immune response.8, 9”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [8] Tatsis, 2004, Adenoviruses as vaccine vectors, Mol Ther source

      Not checked in the free run.

    • cites [9] Dolzhikova, 2017, Safety and immunogenicity of GamEvac-Combi, a heterologous VSV- and Ad5-vectored Ebola vaccine: an open phase I/II trial in healthy adults in Russia, Hum Vaccin Immunother source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Anti-SARS-CoV-2 IgG was tested with an ELISA developed at Gamaleya NRCEM and registered for clinical use in Russia.

    “To test anti-SARS-CoV-2 IgG, we used an ELISA that was developed at Gamaleya NRCEM and registered for clinical use in Russia (P3H 2020/10393 2020-05-18).”
    Quote in the paperNot a substantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductown data

    The trial protocol was reviewed and approved by competent authorities, including the Russian Ministry of Health, the Moscow City Independent Ethics Committee, and local ethics committees.

    “The trial protocol was reviewed and approved by appropriate competent authorities, including the Department of State Regulation for Circulation of Medicines of the Ministry of Health of the Russian Federation (approval number 450 from Aug 25, 2020), Moscow City Independent Ethics Committee, and independent local ethics committees of clinical sites.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    If a participant had a positive PCR test, they were classified as asymptomatic and not counted as a COVID-19 case in the efficacy analysis, per protocol.

    “In the case of a positive PCR test result, participants were classified as asymptomatic and were not counted as COVID-19 cases in the efficacy analysis, according to protocol.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    The statistician generated the sequence used to label the drug.

    “The statistician generated a sequence, according to which the drug was labelled.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductown data

    The serious adverse event analysis included all participants who had received at least one dose at database lock and had no protocol violations.

    “The analysis of serious adverse events included all participants who had received at least one dose at the time of database lock and followed protocol without violations.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    The funding source was not involved in designing the study, collecting or analysing data, interpreting results, or writing the report.

    “The funder had no role in study design, data collection, data analysis, data interpretation, or writing of the report.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The heterologous prime-boost approach is the most effective way to generate a powerful and long-lasting immune response that does not depend on pre-existing immunity to the vector.

    “Thus, the most effective approach for generating a powerful and long-lasting immune response that does not depend on the presence of a pre-existing immune response to the vector is the heterologous prime-boost vaccination approach.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    The drug and placebo were outwardly indistinguishable in packaging, label, and content.

    “The drug and placebo were outwardly indistinguishable (packaging, label, and content).”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    Adenoviral vector vaccines have been extensively studied for safety, and adenoviral vector-based therapeutic drugs are used in clinical practice.

    “The safety of adenoviral vector vaccines has been extensively studied, and adenoviral vector-based therapeutic drugs are used in clinical practice.5, 6, 7”
    Quote in the paperNot a substantial claim0 of 3 sources checked
    • cites [5] Zhang, 2016, Adenoviral vector-based strategies against infectious disease and cancer, Hum Vaccin Immunother source

      Not checked in the free run.

    • cites [6] Wold, 2013, Adenovirus vectors for gene therapy, vaccination and cancer gene therapy, Curr Gene Ther source

      Not checked in the free run.

    • cites [7] Volpers, 2004, Adenoviral vectors for gene transfer and therapy, J Gene Med source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductown data

    The trial was a randomised, double-blind, placebo-controlled, multicentre phase 3 study conducted at 25 hospitals and polyclinics in Moscow, Russia.

    “We did a randomised, double-blind, placebo-controlled, phase 3 trial at 25 hospitals and polyclinics in Moscow, Russia.”
    • Also stated in: § Study design and participants · plain
      “This is a randomised, double-blind, placebo-controlled, multicentre, phase 3 trial to assess efficacy, immunogenicity, and safety of the Gam-COVID-Vac combined vector vaccine against SARS-CoV-2-induced COVID-19 in adults, done at 25 hospitals and polyclinics in Moscow, Russia”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductnone given

    All adverse events were followed until resolution by a clinical investigator and were reviewed by the data safety and monitoring board and verified by the trial monitor.

    “All adverse events were followed up by a clinical investigator until resolution and were reviewed by the data safety and monitoring board and verified by the trial monitor.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Premisecitation

    In phase 1/2 trials, Gam-COVID-Vac had a good safety profile and produced strong humoral and cellular immune responses.

    “A heterologous recombinant adenovirus (rAd)-based vaccine, Gam-COVID-Vac (Sputnik V), showed a good safety profile and induced strong humoral and cellular immune responses in participants in phase 1/2 clinical trials.”
    • Also stated in: § Introduction · boosted
      “The results showed that the vaccine was well tolerated and highly immunogenic in healthy participants.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [12] Logunov, 2020, Safety and immunogenicity of an rAd26 and rAd5 vector-based heterologous prime-boost COVID-19 vaccine in two formulations: two open, non-randomised phase 1/2 studies from Russia, Lancet source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Study design and conductnone given

    Trial participants' EHRs were updated to show trial participation and were used for electronic data capture and source data verification by contract research organisation monitors.

    “EHRs of the trial participants were updated to indicate their participation in the trial and were used as a source for electronic data capture and source data verification by contract research organisation monitors.”
    Quote in the paperNot a substantial claim

  • Classified as probably not a substantial claim.

    Study design and conductnone given

    The primary outcome analysis included all participants who had received at least two doses at database lock and had no protocol violations.

    “The primary outcome analysis included all participants who had received at least two doses at the time of database lock and followed protocol without violations.”
    Quote in the paperSubstantial claim

  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductown data

    Participants were randomly assigned in a 3:1 ratio to vaccine or placebo, with stratification by age group.

    “Participants were randomly assigned (3:1) to receive vaccine or placebo, with stratification by age group.”
    • Also stated in: § Randomisation and masking · plain
      “Enrolled participants were divided into five age strata (18–30 years, 31–40 years, 41–50 years, 51–60 years, and >60 years) and were assigned to two study groups using stratified (block size 4) interactive web response system (IWRS) randomisation in a ratio of 3:1 to the vaccine group or the placebo group.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    BNT162b2 has reported 95% efficacy against COVID-19 in a multinational, placebo-controlled, observer-blinded pivotal efficacy trial.

    “BNT162b2, an mRNA-based vaccine developed by Pfizer/BioNTech has reported 95% efficacy against COVID-19 in a multinational, placebo-controlled, observer-blinded, pivotal efficacy trial.4”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [4] Polack, 2020, Safety and efficacy of the BNT162b2 mRNA Covid-19 vaccine, N Engl J Med source

      Not checked in the free run.

  • May combine two claims.

    Study design and conductown data

    In this interim analysis, duration of protection could not be assessed; median follow-up was 48 days after the first dose.

    “In this interim analysis, we have not been able to assess duration of protection; median follow-up time was 48 days after first dose.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Study design and conductnone given

    Although the study enrolled participants with comorbidities, not all risk groups are represented.

    “Although the study enrolled participants with comorbidities, not all risk groups are represented.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Study design and conductown data

    In the older-than-60 subgroup, proportions of participants by sex (p=0.378), concomitant diseases (p=0.774), and risk of infection (p=0.090) were similar between vaccine and placebo groups.

    “Proportions of participants by sex (p=0·378), incidence of concomitant diseases (p=0·774), and risk of infection (p=0·090) were similar between the vaccine and placebo groups.”
    Quote in the paperNot a substantial claim

  • May combine two claims.

    Interpretationreasoning

    The efficacy analysis was done 21 days after the first dose because the immune response is formed by that time.

    “Therefore, in this study, the efficacy analysis was done 21 days after the first dose, because by that time, the immune response is formed.”
    Quote in the paperSubstantial claim

  • May combine two claims.

    Interpretationown data

    The interim analysis of the randomised, controlled, phase 3 trial of Gam-COVID-Vac in Russia showed high efficacy, immunogenicity, and a good tolerability profile in participants aged 18 years or older.

    “Our interim analysis of the randomised, controlled, phase 3 trial of Gam-COVID-Vac in Russia has shown high efficacy, immunogenicity, and a good tolerability profile in participants aged 18 years or older.”
    Quote in the paperSubstantial claim

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    Interim results of the mRNA-1273 vaccine trial suggest efficacy of 94.1% based on 95 cases of asymptomatic COVID-19 among participants.

    “Interim results of the trial suggest efficacy of 94·1% based on 95 cases of asymptomatic COVID-19 among participants: 90 in the placebo group and five in the study group.3”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [3] Baden, 2020, Efficacy and safety of the mRNA-1273 SARS-CoV-2 vaccine, N Engl J Med

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    The ChAdOx1 nCoV-19 vaccine had reported efficacy of 62.1% after two standard doses, 90.0% after a low dose followed by a standard dose, and 70.4% overall.

    “Among participants who received two standard doses, the reported efficacy of the vaccine was 62·1%, and in participants who received a low dose followed by a standard dose, efficacy was 90·0%, resulting in overall efficacy of 70·4%.2”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [2] Voysey, 2021, Safety and efficacy of the ChAdOx1 nCoV-19 vaccine (AZD1222) against SARS-CoV-2: an interim analysis of four randomised controlled trials in Brazil, South Africa, and the UK, Lancet source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Premisecitation

    WHO target product profiles for COVID-19 vaccines require efficacy of at least 50%, suitability for older adults, a maximum two-dose regimen, and protection for at least 6 months for emergency use during an outbreak.

    “According to WHO target product profiles for COVID-19 vaccines,16 the characteristics required for emergency use during an outbreak include efficacy of at least 50%, suitability for use in older adults, maximum of two-dose regimen, and protection for at least 6 months.”
    Quote in the paperNot a substantial claim0 of 1 sources checked
    • cites [16]

      Not checked in the free run.

  • May combine two claims.

    Study design and conductown data

    COVID-19 cases were detected through self-reported symptoms followed by PCR testing, so only symptomatic cases were included in the efficacy analyses.

    “Furthermore, COVID-19 cases were detected through self report of symptoms by participants, followed by a PCR test, so only symptomatic cases of COVID-19 are included in the efficacy analyses.”
    Quote in the paperSubstantial claim
45 of 45

  • The paper relies on this without support.

    A single immunisation with adenoviral vector-delivered antigens can elicit cellular and humoral immunity, which makes them suitable for emergency prophylaxis during a pandemic.

    “Adenoviral vector-delivered antigens are known to induce both cellular and humoral immunity after a single immunisation, allowing their use as an emergency prophylaxis tool in a pandemic.”
1 of 1

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Self-check

Percentages, sums and reported differences re-computed from the paper’s own numbers.

Each contradiction between two passages listed here was confirmed by an independent check.

  • Cellular assay samples are described as both serum and blood cells

    Minor

    The methods describe the IFN-γ cellular response as measured in cultured peripheral blood mononuclear cells, but the results say serum samples were analysed for that response. Serum does not contain the cells specified for the assay.

1 of 1

No citation lists for this paper

No citation lists for this paper yet — checked again daily.

References 14 · Cited by 1,747

Authors
Logunov, D. Y., Dolzhikova, I. V., Shcheblyakov, D. V., Tukhvatulin, A. I., Zubkova, O. V., Dzharullaeva, A. S., Kovyrshina, A. V., Lubenets, N. L., Grousova, D. M., Erokhova, A. S., Botikov, A. G., Izhaeva, F. M., Popova, O., Ozharovskaya, T. A., Esmagambetov, I. B., Favorskaya, I. A., Zrelkin, D. I., Voronina, D. V., Shcherbinin, D. N., Semikhin, A. S., Simakova, Y. V., Tokarskaya, E. A., Egorova, D. A., Shmarov, M. M., Nikitenko, N. A., Gushchin, V. A., Smolyarchuk, E. A., Zyryanov, S. K., Borisevich, S. V., Naroditsky, B. S., & Gintsburg, A. L.
Affiliations
  • Gamalei Institute of Epidemiology and Microbiology (RU)
  • Ministry of Health of the Russian Federation (RU)
  • Peoples' Friendship University of Russia (RU)
  • Ministry of Defence of the Russian Federation (RU)
Corresponding author
Logunov, Denis Y
ORCID
Venue
The Lancet
Publisher
Elsevier BV
Published
2021-02
Volume
397
Issue
10275
Pages
671-681
ISSN
  • 0099-5355 (ISSN-L)
  • 0140-6736
DOI
10.1016/s0140-6736(21)00234-8
PMC
PMC7852454
OpenAlex
W3127329393
Cited by
1,747
References
14
Citations by year
2026: 38 · 2025: 68 · 2024: 142 · 2023: 264 · 2022: 542 · 2021: 689 · 2020: 2 · 2018: 1 · 2017: 1
FWCI
130.25
Type
journal article
Language
en
Update notices
erratum (2021-02-20)
Open access
Licence
Locations
  • The Lancet (publishedVersion)
  • Europe PMC (PubMed Central) (publishedVersion)
  • PubMed Central (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
  • Health Sciences › Medicine › Infectious Diseases › COVID-19 Clinical Research Studies
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Genetics › Virus-based gene therapy research
Keywords
COVID-19 vaccines, SARS-CoV-2, recombinant adenovirus vector, Rad26, Rad5, heterologous prime-boost, Gam-COVID-Vac, S protein, vaccine efficacy, vaccine safety, serious adverse events, humoral and cellular immune response, SARS-CoV-2 breakthrough infection, Russia, adults
MeSH terms
COVID-19, COVID-19 Vaccines, Adult, Antibodies, Viral, Double-Blind Method, Female, Humans, Immunization, Secondary, Injections, Intramuscular, Male, Middle Aged, Moscow, Vaccines, Synthetic, Spike Glycoprotein, Coronavirus

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

Claims read by deepseek-v4.1-flash under definition version 3 (extract-v3) on 2026-10-06.

Classified by jev-1.13-20260917 (gold-guideline-v0.2) on 2026-10-06.

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review