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Title: Analysis of COVID-19 incidence and severity among adults vaccinated with 2-dose mRNA COVID-19 or inactivated SARS-coV-2 vaccines with and without boosters in Singapore
Authors: Ng, Oon Tek
Marimuthu, Kalisvar
Lim, Nigel
Lim, Ze Qin
Thevasagayam, Natascha May
Koh, Vanessa
Chiew, Calvin J.
Ma, Stefan
Koh, Mingshi
Low, Pin Yan
Tan, Say Beng
Ho, Joses
Maurer-Stroh, Sebastian
Lee, Vernon J. M.
Leo, Yee Sin
Tan, Kelvin Bryan
Cook, Alex R.
Tan, Chorh Chuan
Keywords: Science::Medicine
Issue Date: 2022
Source: Ng, O. T., Marimuthu, K., Lim, N., Lim, Z. Q., Thevasagayam, N. M., Koh, V., Chiew, C. J., Ma, S., Koh, M., Low, P. Y., Tan, S. B., Ho, J., Maurer-Stroh, S., Lee, V. J. M., Leo, Y. S., Tan, K. B., Cook, A. R. & Tan, C. C. (2022). Analysis of COVID-19 incidence and severity among adults vaccinated with 2-dose mRNA COVID-19 or inactivated SARS-coV-2 vaccines with and without boosters in Singapore. JAMA Network Open, 5(8), e2228900-.
Project: MOH-000469 
Journal: JAMA Network Open 
Abstract: Importance: Assessing booster effectiveness of COVID-19 mRNA vaccine and inactivated SARS-CoV-2 vaccine over longer time intervals and in response to any further SARS-CoV-2 variants is crucial in determining optimal COVID-19 vaccination strategies. Objective: To determine levels of protection against severe COVID-19 and confirmed SARS-CoV-2 infection by types and combinations of vaccine boosters in Singapore during the Omicron wave. Design, Setting, and Participants: This cohort study included Singapore residents aged 30 years or more vaccinated with either at least 2 doses of mRNA COVID-19 vaccines (ie, Pfizer-BioNTech BNT162b2 or Moderna mRNA-1273) or inactivated SARS-CoV-2 vaccines (Sinovac CoronaVac or Sinopharm BBIBP-CorV) as of March 10, 2022. Individuals with a known SARS-CoV-2 infection prior to December 27, 2021, an infection on or before the date of their second vaccine dose, or with reinfection cases were excluded. Exposures: Two or 3 doses of Pfizer-BioNTech BNT162b2, Moderna mRNA-1273, Sinovac CoronaVac, or Sinopharm BBIBP-CorV. Main Outcomes and Measures: Notified infections from December 27, 2021, to March 10, 2022, adjusted for age, sex, race, housing status, and calendar days. Estimated booster effectiveness, defined as the relative incidence-rate reduction of severe disease (supplemental oxygen, intensive care, or death) or confirmed infection following 3-dose vaccination compared with 5 months after second mRNA dose, was determined using binomial regression. Results: Among 2441581 eligible individuals (1279047 [52.4%] women, 846110 (34.7%) aged 60 years and older), there were 319943 (13.1%) confirmed SARS-CoV-2 infections, of which 1513 (0.4%) were severe COVID-19 cases. mRNA booster effectiveness against confirmed infection 15 to 60 days after boosting was estimated to range from 31.7% to 41.3% for the 4 boosting combinations (homologous BNT162b2, homologous mRNA-1273, 2-dose BNT162b2/mRNA-1273 booster, and 2-dose mRNA-1273/BNT162b2 booster). Five months and more after boosting, estimated booster effectiveness against confirmed infection waned, ranging from -2.8% to 14.6%. Against severe COVID-19, estimated mRNA booster effectiveness was 87.4% (95% CI, 83.3%-90.5%) 15 to 60 days after boosting and 87.2% (95% CI, 84.2%-89.7%) 5 to 6 months after boosting, with no significant difference comparing vaccine combinations. Booster effectiveness against severe COVID-19 15 days to 330 days after 3-dose inactivated COVID-19 vaccination, regardless of combination, was estimated to be 69.6% (95% CI, 48.7%-81.9%). Conclusions and Relevance: Booster mRNA vaccine protection against severe COVID-19 was estimated to be durable over 6 months. Three-dose inactivated SARS-CoV-2 vaccination provided greater protection than 2-dose but weaker protection compared with 3-dose mRNA.
ISSN: 2574-3805
DOI: 10.1001/jamanetworkopen.2022.28900
Schools: Lee Kong Chian School of Medicine (LKCMedicine) 
Organisations: National Centre for Infectious Diseases, Singapore
Tan Tock Seng Hospital
Yong Loo Lin School of Medicine, NUS
National University Health System, Singapore
Saw Swee Hock School of Public Health
Rights: © 2022 Ng OT et al. JAMA Network Open. This is an open access article distributed under the terms of the CC-BY License.
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:LKCMedicine Journal Articles

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