By Elisha Singira

In the first data assessing the effectiveness of a mixed four-dose COVID-19 vaccine, the AstraZeneca vaccine was found to be 73% effective in preventing COVID-19 infections of the Omicron variant.

The effectiveness of AstraZeneca was found in a test-negative, case-controlled analysis of data for the province of Chiang Mai, Northern Thailand, from the Ministry of Public Health Immunization Centre (MOPH IC) database, which was designed to estimate Vaccine Effectiveness (VE) against SARS-CoV-2 infection (COVID-19) of various mixed vaccination schedules.

According to the new data from Thailand’s Chiang Mai University, AstraZeneca’s COVID-19 Vaccine proved to be highly effective against the highly transmissible Omicron variant when a fourth dose was given on top of any previous primary or booster vaccine.

During the study, AstraZeneca’s COVID-19 Vaccine was found to be similar to that seen with mRNA vaccines such as Moderna and Pfizer which showed a VE of 71% (VE 71%, 95% CI 59-79%).

The research was focused on certain aspects such as age, gender, calendar time and preceding vaccine series type to come up with the findings on the effectiveness.

Emeritus Professor Suwat Chariyalertsak, MD, Dr.PH, Faculty of Public Health, Chiang Mai University, Thailand, posited that the study provided much-needed data that showed the fourth dose of any COVID-19 vaccine can help prevent infection due to the highly contagious Omicron variant.

He reiterated that providing continuous protection with boosting is important, especially for the risk groups such as the elderly and those living with chronic health conditions.

According to him, the data also supports the effectiveness of  mix and match, vaccination schedules which may help ongoing efforts to increase population coverage of booster doses.

John Perez, Senior Vice President, Head of Late development, vaccines & immune therapies, AstraZeneca, added that these new data further add to the understanding of the importance of booster doses to protect against COVID-19 infection in an evolving variant landscape.

He added that building on AstraZeneca’s COVID-19 Vaccine’s effectiveness in preventing severe disease and death, they now know that AstraZeneca’s COVID-19 Vaccine can help prevent Omicron-related infections when given as a fourth dose, with greater protection against infection than was seen following a third dose.

The study reported real-world VE of AstraZeneca’s COVID-19 Vaccine and mRNA vaccines utilizing an active surveillance network which enabled comparisons of the same patient profiles across both Delta-predominant and Omicron-predominant periods.

Notably, over 3 billion doses of AstraZeneca’s COVID-19 Vaccine have been released, which based on model outcomes is estimated to have helped save over 6 million lives between 08 December 2020 and 08 December 2021.