Effectiveness of COVID-19 vaccines in preventing infection among high-risk contacts at Mae Sot district, Tak province

Abstract

COVID-19 is a contagious disease that is spreading around the world, a new strain of virus that has never been found before in humans. The pathology of the disease occurs directly in the respiratory system and therefore can spread from person to person. Currently, vaccines are being developed that can prevent infection and reduce mortality. This cross-sectional study aimed to study the effectiveness of COVID-19 vaccines in preventing infection among high-risk contacts at Mae Sot district, Tak Province. The sample were 1,213 cases of high-risk contacts of COVID-19 infection at Mae Sot district, Tak province. Data were collected from high-risk contacts including gender, age, occupation, number of vaccines, Real Time PCR results of infection detection, and the number of vaccine injections received for prevention of COVID-19 infection during the period 1 October 2021 to 30 March 2022. Statistical data analysis included frequency, percentage, median and Odds ratio (OR).

The results showed that the effectiveness of vaccination for high-risk contacts with at least one dose compared to high-risk contacts who were not vaccinated was effective in preventing COVID-19 disease by 51% (OR=0.49, 95%CI=0.32-0.75, p=0.001). While, high-risk contacts who received 3 - 4 doses of the vaccine compared to those received one does of the vaccine were more effective in preventing COVID-19 by 67% (OR=0.33, 95%CI=0.14-0.81, p=0.012). Moreover, high-risk contacts who received 3 - 4 doses of the vaccine compared to 1-2 doses of the vaccine, the effectiveness in preventing COVID-19 disease was 74% (OR=0.26, 95%CI=0.12-0.56, p<0.001).

In conclusion, receiving 3 or more vaccine doses can protect against COVID-19 disease and is very useful in preventing and controlling the spread of COVID-19 that resulting in fewer infections and no patient death in this study.