Evaluation of CoronaVac and CoviShield Vaccines on SARS-CoV-2 Infection in Healthcare Workers in Salvador, Brazil

The emergence and rapid spread of the SARS-CoV-2 Gamma variant in Brazil have raised concerns about SARS-CoV-2 vaccines’ neutralizing capacity and viral load impact. Our study aimed to assess the influence of the CoviShield and CoronaVac vaccines on the Ct-N2 value in the healthcare organization’s staff who experienced primary SARS-CoV-2 infection. We examined sixty-three COVID-19 cases reported in the first half of 2021 and identified similar clinical and laboratory characteristics among individuals, regardless of the vaccine they received. Surprisingly, our observations revealed that both CoviShield and CoronaVac vaccines had no impact on viral load or the development and severity of symptoms. These findings suggest a potential reduction in neutralizing response and indicate the need to consider the incorporation of other SARS-CoV-2 vaccines and maintain additional containment measures against SARS-CoV-2, as they remain imperative despite vaccination efforts.