An Effectiveness Study of the Sinovac's Adsorbed COVID-19 (Inactivated) Vaccine

Summary

This is a stepped-wedge cluster randomized trial to assess effectiveness of Sinovac's Adsorbed COVID-19 (Inactivated) vaccine. Residents in the urban area of a municipality are eligible to participate. The city was divided in clusters and those cluster were grouped to determine the offer of vaccination in four steps. The vaccine will be offered to adults (18 years old and above) according to the location of their homes in a cluster. The vaccine schedule is two doses with four-weeks interval. Baseline samples to determine previous immunity will be collected before vaccination. Cases of COVID-19 reported in the city will be recorded according to the WHO clinical progression scale. Comparison of periods before and after vaccination and relation to immunization coverage will be considered for the assessment of effectiveness in the clusters and groups of clusters.

Timeline

Start

2021-02-07

Primary completion

2023-03-07

Completion

2023-07-20

Publications

• Borges MC, Palacios R, Conde MTRP, Volpe GJ, Ferreira NN, Garibaldi PMM, Fonseca BAL, Calado RT, Coutinho BM, Gomes BBM, de Lima Dias CFS, de Moraes GR, Haddad SK, de Miranda EJFP, Braga PE, Ragiotto L, Franca JID, de Lima MA, de Oliveira Alves LB, de Camargo Vieira Tenorio J, Sampaio SC, Covas DT, Dos Santos Almeida MAAL, Morandi Junior E, Boulos FC. Indirect protection and long-term effectiveness of inactivated COVID-19 vaccine: a stepped-wedge randomised trial in Serrana, Brazil. Sci Rep. 2026 Feb 19;16(1):9879. doi: 10.1038/s41598-026-37815-1.

Drugs

Indications