Título

EFFECTIVENESS OF COVID-19 VACCINE BOOSTER DOSES AGAINST OMICRON-RELATED SERIOUS DISEASE IN BRAZIL

Introdução

Background
COVID-19 vaccines have been highly effective in reducing morbidity and mortality during the pandemic. However, the emergence of the highly transmissible Omicron variant of concern (VOC) and its subvariants has led to some questions about the effectiveness of the current vaccines against this strain.

Objective
As first and second booster doses are rolled out across Latin America, our aim was to determine how effective the continent’s most widely used vaccines (BNT162b2, AZD1222, Ad26.COV2-S, CoronaVac) were in preventing Omicron-related serious disease following a booster dose.

Material e Método

Methods
A regional group of experts reviewed vaccine effectiveness (VE) data extracted from the global, publicly available database maintained by the International Vaccine Access Center (IVAC; Johns Hopkins Bloomberg School of Public Health, US). The analysis (of studies published between 1 January and 30 June 2022) focused on the effectiveness of a booster dose, whether that be third or in some cases second dose (Ad26.COV2.S), in Brazil.

Resultados

Results
In the Brazilian dataset, we observed that whilst all current COVID-19 vaccines showed reduced protection against Omicron-related symptomatic infection compared with previous variants (Mean VE = 37.9%), most homologous and heterologous boosted schedules demonstrated high protection against severe disease (>84%) (Table 1). This was independent of age and vaccine type, except for homologous CoronaVac-boosted schedule that demonstrated slightly reduced VE against severe disease (75.8%). These regional data are consistent with that seen in a larger global dataset analysed.

Discussão e Conclusões

Conclusion
This review reinforces the value of completion of booster vaccination to restore VE against VOCs such as Omicron and its subvariants, particularly in those at higher risk of COVID-19 (age >60 years). It also provides reassuring evidence that the Brazilian region’s most widely used vaccines are effective in preventing severe COVID-19 in the Omicron-dominant era.

Palavras Chave

EFFECTIVENESS OF COVID-19 VACCINE BOOSTER DOSES AGAINST OMICRON-RELATED SERIOUS DISEASE IN BRAZIL