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. 2023 Jun 22;3(1):e104.
doi: 10.1017/ash.2023.173. eCollection 2023.

Longer-term effectiveness of a heterologous coronavirus disease 2019 (COVID-19) vaccine booster in healthcare workers in Brazil

Alexandre R Marra  1   2 , João Luiz Miraglia  1 , Daniel Tavares Malheiro  1 , Yang Guozhang  1 , Vanessa Damazio Teich  1 , Elivane da Silva Victor  1 , João Renato Rebello Pinho  1 , Adriana Cypriano  1 , Laura Wanderly Vieira  1 , Miria Polonio  1 , Rafael Herrera Ornelas  1 , Solange Miranda de Oliveira  1 , Flavio Araujo Borges  1 , Silvia Cristina Cassiano Oler  1 , Victória Catharina Volpe Ricardo  1 , Aline Miho Maezato  1 , Gustavo Yano Callado  1 , Guilherme de Paula Pinto Schettino  1 , Ketti Gleyzer de Oliveira  1 , Rúbia Anita Ferraz Santana  1 , Fernanda de Mello Malta  1 , Deyvid Amgarten  1 , Ana Laura Boechat  1 , Takaaki Kobayashi  2 , Jorge L Salinas  3 , Michael B Edmond  4 , Luiz Vicente Rizzo  1
Affiliations

Longer-term effectiveness of a heterologous coronavirus disease 2019 (COVID-19) vaccine booster in healthcare workers in Brazil

Alexandre R Marra et al. Antimicrob Steward Healthc Epidemiol. .

Abstract

Objective: To compare the long-term vaccine effectiveness between those receiving viral vector [Oxford-AstraZeneca (ChAdOx1)] or inactivated viral (CoronaVac) primary series (2 doses) and those who received an mRNA booster (Pfizer/BioNTech) (the third dose) among healthcare workers (HCWs).

Methods: We conducted a retrospective cohort study among HCWs (aged ≥18 years) in Brazil from January 2021 to July 2022. To assess the variation in the effectiveness of booster dose over time, we estimated the effectiveness rate by taking the log risk ratio as a function of time.

Results: Of 14,532 HCWs, coronavirus disease 2019 (COVID-19) was confirmed in 56.3% of HCWs receiving 2 doses of CoronaVac vaccine versus 23.2% of HCWs receiving 2 doses of CoronaVac vaccine with mRNA booster (P < .001), and 37.1% of HCWs receiving 2 doses of ChAdOx1 vaccine versus 22.7% among HCWs receiving 2 doses of ChAdOx1 vaccine with mRNA booster (P < .001). The highest vaccine effectiveness with mRNA booster was observed 30 days after vaccination: 91% for the CoronaVac vaccine group and 97% for the ChAdOx1 vaccine group. Vacine effectiveness declined to 55% and 67%, respectively, at 180 days. Of 430 samples screened for mutations, 49.5% were SARS-CoV-2 delta variants and 34.2% were SARS-CoV-2 omicron variants.

Conclusions: Heterologous COVID-19 vaccines were effective for up to 180 days in preventing COVID-19 in the SARS-CoV-2 delta and omicron variant eras, which suggests the need for a second booster.

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Conflict of interest statement

All authors report no conflict of interest relevant to this article.

Figures

Figure 1.
Figure 1.
Effectiveness of 2 doses of Oxford-AstraZeneca (ChAdOx1) [red] or CoronaVac [gray] with a third (booster) dose with mRNA (Pfizer/BioNTech) vaccine, excluding those with previous COVID-19.
Figure 2.
Figure 2.
Effectiveness of 2 doses of Oxford-AstraZeneca (ChAdOx1) [green] or CoronaVac [purple] with a third (booster) dose with mRNA (Pfizer/BioNTech) vaccine, including those with previous COVID-19
See this image and copyright information in PMC

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