Effectiveness of the CoronaVac® vaccine in a region of the Colombian Amazon, was herd immunity achieved?

• Published in: Tropical Diseases, Travel Medicine and Vaccines
• Main Authors: Héctor Serrano-Coll, Hollman Miller, Camilo Guzmán, Ricardo Rivero, Bertha Gastelbondo, Jorge Miranda, Ketty Galeano, Jhon Montaña-Restrepo, Salim Mattar
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2022
• Subjects: COVID-19 vaccines; Prevention; Post-exposure; Prophylaxis; Public health; Mass vaccination; Arctic medicine. Tropical medicine; RC955-962; Arctic
• Online Access: https://doi.org/10.1186/s40794-021-00159-x; https://doaj.org/article/6fd89f9e310943a8b1585da6232cf3c5

Abstract Introduction Currently, more than 4.5 billion doses of SARS-CoV-2 vaccines have been applied worldwide. However, some developing countries are still a long way from achieving herd immunity through vaccination. In some territories, such as the Colombian Amazon, mass immunization strategies have been implemented with the CoronaVac® vaccine. Due to its proximity to Brazil, where one of the variants of interest of SARS-CoV-2 circulates. Objective To determine the effectiveness of the CoronaVac® vaccine in a population of the Colombian Amazon. Methods Between February 24, 2021, and August 10, 2021, a descriptive observational study was carried out in which a population of individuals over 18 years of age immunized with two doses of the CoronaVac® vaccine was evaluated. The study site was in the municipality of Mitú, Vaupés, in southeastern Colombia, a region located in the Amazon bordering Brazil. Results. 99% of the urban population of the Mitú municipality were vaccinated with CoronaVac®. To date, 5.7% of vaccinated individuals have become ill, and only 0.1% of these require hospitalization. One death was attributable to COVID-19 has been reported among vaccinated individuals, and the vaccine has shown 94.3% effectiveness against mild disease and 99.9% against severe infection. Conclusions The herd immunity achieved through mass vaccination in this population has made it possible to reduce the rate of complicated cases and mortality from COVID-19 in this region of the Colombian Amazon. Highlights CoronaVac® has shown 94.3% effectiveness against mild disease and 99.9% against severe infection in this indigenous population. CoronaVac® reduces the mortality rate from 2.2% in 2020 to 0.22% in 2021. The herd immunity was achieved through mass vaccination in this region of the Colombian Amazon.