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Boosters provide same immunity to all, even to recipients of Sinovac

Boosters provide same immunity to all, even to recipients of Sinovac
FRIDAY, August 05, 2022

A booster shot provides the same level of immunity against Covid-19 to people whose first two shots have been either inactivated or mRNA vaccines, a top virologist said.

In a Facebook post on Friday, Dr Yong Poovorawan said he and his team have been studying the administration of Covid-19 vaccines in Thailand for the past year and a half.

His latest study, titled “Immunogenicity of the BNT162b2 COVID-19 vaccine as a third dose (booster) following two doses of different primary series regimens in Thailand”, was published in the National Library of Medicine (NIH) website ( on Wednesday.

The subjects of the study were people who had received an mRNA booster shot (Pfizer) after receiving the first two jabs in Thailand.

He said people who had received two shots of the inactivated vaccines, especially Sinovac, developed similar immunity against Covid-19 as those whose first two jabs had been mRNA vaccines.

His team also studied the effects of different boosters on people whose first two vaccines were a combination of Sinovac and AstraZeneca.

This study, titled “Effects of boosted mRNA and adenoviral-vectored vaccines on immune responses to omicron BA.1 and BA.2 following the heterologous CoronaVac/AZD1222 vaccination”, was published on the NIH website ( on Thursday.

This study shows that all booster doses provide similar immunity against the BA.1 and BA.2 subvariants.

Dr Yong and his team also studied the administration of the India-produced Covovax and the US-manufactured Novavax vaccines as a booster.

Results of this study showed that those who have received two doses of these inactivated vaccines had developed similar immunity as those who had received two mRNA jabs.

In the post, Dr Yong said that so far, 20 studies led by him and his team had been published in international medical journals and some governments implemented his suggestions. For instance, he said, the Public Health Ministry here adopted the mix-and-match vaccine formula, while the World Health Organisation based its advice on some of his studies.