mRNA-1273 COVID-19 vaccine effectiveness against the B.1.1.7 and B.1.351 variants and severe COVID-19 disease in Qatar

Abstract

In a randomized clinical trial, the mRNA-1273 (Moderna) vaccine had a reported efficacy of 94.1% in preventing symptomatic coronavirus disease 2019 due to infection with wild-type variants 1 . The first immunization using this vaccine in Qatar was recorded on 28 December 2020, but mass vaccination did not start until late February 2021 with the accelerated arrival of vaccine shipments. As the vaccination campaign was scaled up, the country experienced two back-to-back severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) waves that were triggered by the introduction and expansion of the B.1.1.7 (Alpha 2 ) and B.1.351 (Beta 2 ) variants 3 . This created a unique epidemiological opportunity to assess the real-world effectiveness of this vaccine against infection with these variants of concern, as well as against severe forms of COVID-19 disease. ResultsStudy population. Between 28 December 2020 and 10 May 2021, 256,037 individuals in Qatar received at least one dose of the mRNA-1273 vaccine and 181,304 completed the two-dose regimen. Among those with a vaccination record, the median dates at first and second dose were 5 and 29 April 2021, respectively. The median time elapsing between the first and second doses was 28 days (interquartile range (IQR): 28-29 days), with 94.6% of individuals receiving their second dose ≤30 days after the first dose.Flowcharts describing the population selection process for investigation and estimation of vaccine effectiveness are presented in Extended Data Figs. 1-3, and the demographic characteristics of the sample for each outcome of vaccine effectiveness are presented in Table 1. Median age in the study sample for estimation of vaccine effectiveness against infection with B.1.1.7 was 31 years (IQR: 19-38), against infection with B.1.351 was 32 years (IQR: 25-39) and against severe, critical or fatal disease was 43 years (IQR: 37-51). Of note is that Qatar has a young and diverse demographic, where only 9% of its resident population are >50 years of age and 89% are expatriates from >150 countries 4,5 .

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“…In our study, we observed an increased risk of infection 7-13 days after vaccination. Other studies also found an increased risk of SARS-CoV-2 infection up to 14 days after one dose 25314142. This could be due to an increase in exposures to SARS-CoV-2 after vaccination.…”

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“…The COVID-19 pandemic has taken an unprecedented toll on global health and economy, impacting billions of lives all over the world. Importantly, the ongoing vaccination efforts appear to curtail the spread of SARS-CoV-2 and prevent severe disease, even as new virus variants emerge 4,5 . Yet, a prevailing question concerns whether and how exposure to SARS-CoV-2 by infection or immunization might result in long-term protective immunity.…”

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