Viral loads of Delta-variant SARS-CoV-2 breakthrough infections after vaccination and booster with BNT162b2
Open accessPublished version of a preprint
Abstract
The effectiveness of the coronavirus disease 2019 (COVID-19) BNT162b2 vaccine in preventing disease and reducing viral loads of breakthrough infections (BTIs) has been decreasing, concomitantly with the rise of the Delta variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, it is unclear whether the observed decreased effectiveness of the vaccine in reducing viral loads is inherent to the Delta variant or is dependent on time from immunization. By analyzing viral loads of over 16,000 infections during the current, Delta-variant-dominated pandemic wave in Israel, we found that BTIs in recently fully vaccinated individuals have lower viral loads than infections in unvaccinated individuals. However, this effect starts to decline 2 months after vaccination and ultimately vanishes 6 months or longer after vaccination. Notably, we found that the effect of BNT162b2 on reducing BTI viral loads is restored after a booster dose. These results suggest that BNT162b2 might decrease the infectiousness of BTIs even with the Delta variant, and that, although this protective effect declines with time, it can be restored, at least temporarily, with a third, booster, vaccine dose.
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Community protection due to reduced viral loads in infected but fully vaccinated individuals is diminishing over time.
“It is becoming increasingly clear that community protection owing to reduced viral loads in infected but fully vaccinated individuals is diminishing over time159, thereby facilitating further outbreaks and the rapid expansion of new VOCs160–162.”
From COVID-19 and cellular senescence (2023) · cites this paper as [159]
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References 39 · Cited by 222
Research works printed but not linked: 10
- Chodick, G. et al. Assessment of effectiveness of 1 dose of BNT162b2 vaccine for SARS-CoV-2 infection 13 to 24 days after immunization. JAMA Netw. Open 4, e2115985 (2021).
- Petter, E. et al. Initial real world evidence for lower viral load of individuals who have been vaccinated by BNT162b2. Preprint at https://www.medrxiv. org/content/10.1101/2021.02.08.21251329v1 (2021). · DOI
- Gazit, S. et al. BNT162b2 mRNA vaccine effectiveness given confirmed exposure; analysis of household members of COVID-19 patients. Preprint at https://www.medrxiv.org/content/10.1101/2021.06.29.21259579v1 (2021). · DOI
- Goldberg, Y. et al. Waning immunity of the BNT162b2 vaccine: a nationwide study from Israel. Preprint at https://www.medrxiv.org/content/10.1101/2021. 08.24.21262423v1 (2021). · DOI
- Chia, P. Y. et al. Virological and serological kinetics of SARS-CoV-2 Delta variant vaccine-breakthrough infections: a multi-center cohort study. Preprint at https://www.medrxiv.org/content/10.1101/2021.07.28.21261295v1 (2021). · DOI
- Kissler, S. M. et al. Viral dynamics of SARS-CoV-2 variants in vaccinated and unvaccinated individuals. Preprint at https://www.medrxiv.org/content/10.110 1/2021.02.16.21251535v3 (2021). · DOI
- Corbett, K. S., Gagne, M., Wagner, D. & O'Connell, S. Protection against SARS-CoV-2 Beta variant in mRNA-1273 boosted nonhuman primates. Preprint at https://www.biorxiv.org/content/10.1101/2021.08.11. 456015v1 (2021). · DOI
- Levine-Tiefenbrun, M. et al. Association of COVID-19 RT-qPCR test false-negative rate with patient age, sex and time since diagnosis. Preprint at https://www.medrxiv.org/content/10.1101/2020.10.30.20222935v2 (2020). · DOI
- Xin, H. et al. The incubation period distribution of coronavirus disease 2019 (COVID-19): a systematic review and meta-analysis. Clin. Infect. Dis. https://doi.org/10.1093/cid/ciab501 (2021). · DOI
- Fajnzylber, J. et al. SARS-CoV-2 viral load is associated with increased disease severity and mortality. Nat. Commun. 11, 5493 (2020).
- Authors
- Levine-Tiefenbrun, M., Yelin, I., Alapi, H., Katz, R., Herzel, E., Kuint, J., Chodick, G., Gazit, S., Patalon, T., & Kishony, R.
- Affiliations
- Tel Aviv University (IL)
- Technion – Israel Institute of Technology (IL)
- Maccabi Healthcare Services (IL)
- Corresponding author
- Patalon, Tal
- Kishony, Roy
- ORCID
- Venue
- Nature Medicine
- Published
- 2021-11-02
- Volume
- 27
- Issue
- 12
- Pages
- 2108-2110
- ISSN
- 1078-8956 (ISSN-L)
- 1546-170X
- OpenAlex
- W3209028723
- Cited by
- 222
- References
- 39
- Citations by year
- 2026: 5 · 2025: 11 · 2024: 20 · 2023: 39 · 2022: 132 · 2021: 15
- FWCI
- 16.34
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Nature Medicine (publishedVersion)
- medRxiv (acceptedVersion, cc-by-nc)
- PubMed (publishedVersion)
- Funders
- Israel Science Foundation (3633/19)
- Topics
- Health Sciences › Medicine › Infectious Diseases › SARS-CoV-2 and COVID-19 Research
- Physical Sciences › Mathematics › Modeling and Simulation › COVID-19 epidemiological studies
- Health Sciences › Medicine › Infectious Diseases › COVID-19 Clinical Research Studies
- Keywords
- SARS-CoV-2, Delta variant, breakthrough infection, viral load, BNT162b2, COVID-19 vaccines, booster vaccination, waning vaccine effectiveness, infectiousness, time since vaccination, Israel
- MeSH terms
- COVID-19, SARS-CoV-2, COVID-19 Vaccines, BNT162 Vaccine, Breakthrough Infections, Antibodies, Viral, Humans, Immunization, Secondary, Israel, Time Factors, Vaccination, Viral Load, Antibodies, Neutralizing
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