key: cord-0916781-ju87prqm
authors: Premikha, M; Chiew, Calvin J.; Wei, Wycliffe E.; Leo, Yee-Sin; Ong, Benjamin; Lye, David Chien; Lee, Vernon J.; Tan, Kelvin Bryan
title: Comparative Effectiveness of mRNA and Inactivated Whole Virus Vaccines against COVID-19 Infection and Severe Disease in Singapore
date: 2022-04-12
journal: Clin Infect Dis
DOI: 10.1093/cid/ciac288
sha: 8189c85bbca54704e492b35544ec8998f4c1273f
doc_id: 916781
cord_uid: ju87prqm

Compared to individuals vaccinated with Pfizer-BioNTech/Comirnaty, recipients of Sinovac-CoronaVac and Sinopharm were 2.37 (95% CI 2.29–2.46) and 1.62 (95% CI 1.43–1.85) times more likely to be infected with COVID-19 respectively, while individuals vaccinated with Moderna were 0.42 (95% CI 0.25–0.70) times less likely to develop severe disease.

was also available at private healthcare institutions via a special access route and not under the 7 NVP. As of 12 December 2021, 96% of the eligible population in Singapore (excluding children 8 below 12 years old) have received at least two doses of the Pfizer-BioNTech/Comirnaty, 9 Moderna, Sinovac-CoronaVac or Sinopharm vaccines. 10 COVID-19 cases in Singapore increased in September 2021, driven by the more 11 transmissible Delta variant first detected locally in May 2021 to a peak of over 5,000 cases a 12 day. While the majority of cases (~99%) were mild, the number of severe cases and deaths 13 increased, disproportionately driven by unvaccinated individuals 1 . 14 As several studies have suggested that mRNA vaccines have higher vaccine efficacy than 15 non-mRNA vaccines, 2,3 this study aims to compare the relative effectiveness of the four 16 available vaccines in Singapore in preventing COVID-19 infection and severe disease. While a 17 few studies have compared the efficacies of various COVID-19 vaccines, 4-6 we aim to compare 18 the mRNA and inactivated whole virus vaccines in the same population as the findings will be 19 useful for guiding policy recommendations to prevent infection and reduce strain on the 20 healthcare system.

We examined the incidence of COVID-19 infection and severe disease during the study 2 period from 1 October to 21 November 2021 among individuals aged 20 years and above who 3 had received two doses under the NVP in Singapore. The age cut-off was selected in view of the 4 minimum age (18 years old) required to receive Moderna and Sinovac-CoronaVac under the 5 NVP. Individuals who were partially vaccinated or boosted with a third dose or had previous 6 history of COVID-19 infection were excluded. We restricted the cohort to those 2 weeks after 7 completion of two doses of vaccine to allow for sufficient immune response, and who had 8 received their second vaccine dose within 120 days of our analysis to control for immunity 9 waning. Severe disease was defined as ever requiring oxygen supplementation in hospital, 10 admission to intensive care unit (ICU) or death. 11 Using a Poisson regression model, we estimated the incidence rate ratio (IRR) of 12 confirmed COVID-19 infection and severe disease, controlling for age group, gender, ethnicity, 13 residency status and housing type (as a marker of socioeconomic status) as covariates. In CoronaVac and 20,299 (1%) received Sinopharm. 107,220 individuals were confirmed by PCR to 8 be infected with COVID-19 over the study period, and 644 developed severe disease. 9 After adjusting for age, gender, ethnicity, residency status, socioeconomic status, time 10 since second dose and daily infection rate, individuals vaccinated with Sinovac-CoronaVac were 11 more likely to be infected (adjusted IRR 2.37; 95% CI 2.29 -2.46), and more likely to develop 12 severe disease (adjusted IRR 4.59; 95% CI 3.25 -6.48); individuals vaccinated with Sinopharm 13 were also at higher risk of infection (adjusted IRR 1.62; 95% CI 1.43 -1.85), while individuals 14 vaccinated with Moderna were at lower risk of severe disease (adjusted IRR 0.42; 95% CI 0.25 -15 0.70), compared with those who received Pfizer-BioNTech/Comirnaty (Table 1) . 16 As migrant workers on work permits mostly received Moderna and were predominantly 17 male, the analysis was re-run on a subset of the study cohort excluding work permit holders, 18 and similar IRR estimates were observed (Supplementary Materials Table S1 ). Our study is based on comprehensive national data on COVID-19 vaccination, PCR-3 confirmed infections and disease severity. However, there are several limitations. First, we rely 4 on the assumption that all four vaccines did not experience differential waning of immunity. 

Considerations in boosting COVID-19 vaccine immune 4 responses

Accessed 12

Comparative Effectiveness of Moderna

& Johnson) Vaccines in Preventing

Hospitalizations Among Adults Without Immunocompromising Conditions -United States

Comparing the clinical efficacy of COVID-19 14 vaccines: a systematic review and network meta-analysis

A systematic review of COVID-19 vaccine efficacy and 17 effectiveness against SARS-CoV-2 infection and disease

Comparing COVID-19 vaccines for their 21 characteristics, efficacy and effectiveness against SARS-CoV-2 and variants of concern

Efficacy and Safety of the mRNA-1273 SARS-CoV-2

Comparative immunogenicity of mRNA and inactivated 7 vaccines against COVID-19

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Effectiveness of an Inactivated SARS-CoV-2 Vaccine 11 in Chile

Comparison of antibody and T cell responses elicited 14 by BBIBP-CorV (Sinopharm) and BNT162b2 (Pfizer-BioNTech) vaccines against SARS-CoV-2 in 15 healthy adult humans

Pfizer-BioNTech and Sinopharm: A 19 Comparative Study on Post-Vaccination Antibody Titers