Publication date: Jul 25, 2025
Covid-19 remains a global threat due to vaccine-waning immune responses, and the need to update to emerging variants. This study presents the post-unblinding analysis of the PROFISCOV trial (NCT04456595), a double-blind, randomized, placebo-controlled phase 3, among adult healthcare workers (HCWs≥18y). A cohort (N = 12,688) was randomized to receive a two-dose regimen of the inactivated COVID-19 vaccine (CoronaVac) or placebo (1:1), 14 days apart. ANVISA granted emergency use authorization for CoronaVac in January 2021, prompting the study’s unblinding. Outcomes included incidence of symptomatic confirmed COVID-19 cases (RT-PCR), immune response over one year, and effects of boosters among the vaccinees. Population (N = 1554) exhibited a reduction in confirmed cases from November 2021, peaking from December 2021 to February 2022, when the Omicron wave prevailed. Mean IgG-RBD titres increased from baseline to the 52nd week. IgG-N titres peaked in the 13th week and declined. The homologous booster enhanced significantly the immune response compared to the heterologous one (Pfizer).
| Concepts | Keywords |
|---|---|
| February | CoronaVac |
| Healthcare | Healthcare workers |
| Heterologous | Homologous booster |
| Nct04456595 | SARS-CoV-2 incidence |
Semantics
| Type | Source | Name |
|---|---|---|
| disease | IDO | immune response |
| disease | MESH | Covid-19 |
| disease | MESH | emergency |