KKU doctors confirm, those receiving two shots of Sinovac should get a booster to help prevent Covid-19 crisis

Monday August 16, 2021 – Khon Kaen University met the press to release news about the research on immunity of those receiving Sinovac. KKU Medical Team led by Prof. Surasak Wongratanacheewin, Ph.D., Dean of the Graduate School; Asst. Prof. Supranee Pantanawiboon, Ph.D., a lecturer of Department of Microbiology of the Faculty of Medicine, as the research team leader; Asst. Prof. Athibodee Meesing, M.D., a lecturer of the Department of Medicine, Faculty of Medicine; Ajarn Natsamol Tanakulrungsarit, Assistant to the President for Special Affairs joined at the press meeting, which took place at Sarasin Room, Sirikunakorn Building, Khon Kaen University.

Meeting the press to report news about the research results on immunity of those receiving Sinovac by the research team of the Faculty of Medicine, Khon Kaen University.

With reference to the preparation against Covid-19 pandemic in Thailand, inactivated vaccine has been imported for the front-line personnel before other boosters of Viral Vector Vaccine and mRNA at a later stage.

Prof. Surasak Wongratanacheewin, Ph.D., Dean of the Graduate School, as the project advisor said that Khon Kaen University as the oldest academic institution in the Northeast has a policy to assist the society in all aspects. During the spread of Covid-19, which is becoming severe in Thailand now, KKU sees the importance in carrying out a research study on Covid-19 vaccination with hope that the pandemic could be contained and Thai society resumes its normal condition. KKU therefore supports this project, which is on the immunity of 2-shot receivers of Sinovac, both in terms of antibody and cell. It is the first time to report about the cell-related immunity of people receiving this vaccine. The result will be used as guidelines for future disease prevention.

Asst. Prof. Supranee Pantanawiboon, Ph.D., a lecturer of Department of Microbiology of the Faculty of Medicine, the research project leader, explained that virus is a micro-organism that multiplies in cells. Our immunity that works in killing the virus consists of antibody immunity and T cell immunity. Antibody will stop the virus to enter cells. But whenever the virus does enter the cells, the cell immunity will take action to remove the infected cell so that the virus will stop multiplying and invading us. Thus, efficient prevention against the virus necessitates two immunities.

“The research work on checking the immunity of people receiving Sinovac involved doctors, nurses, medical students and related officers, totaling 335 people. We collected data from blood samples, which were taken 3 times: the first time before vaccination, the second after the first vaccination and the third one month after the second vaccination (Figure 1). 89% of vaccinated volunteers were found to be able to build antibody specific to protein of the virus after the first vaccination. After two injections, the amount of specific antibody was present in all volunteers (100%), in different amount, but the medium parameter being at 1292 AU/ml (Figure 1). The study on cells showed that the amount stimulated of CD4+ T cell in volunteers was slightly higher after injection while CD8+ T cell remained unchanged when compared to the time before vaccination (Figure 2).

Figure 1 The antibody level specific to the receptor binding domain of the virus of volunteers before and after receiving Sinovac (n=335)

Figure 2 Percentages of CD4+ and CD8+ T cell that had been stimulated, of volunteers before and after receiving Sinovac (n=153)

Asst. Prof. Supranee added that it can be concluded from the preliminary study that Sinovac vaccination in the experimented group can raise antibody immunity well, but the changes of T cell is little. Therefore, it is recommended that those who received 2 sinovac injections should receive a booster of another vaccine that is not in the inactivated group, in order to increase the efficiency of disease prevention. After the use of another type of vaccine in this group of volunteers, another study on antibody and cell immunity will be conducted again.

Asst. Prof. Athibodee Meesing, M.D., a lecturer of the Department of Medicine, Faculty of Medicine said that the research study informs us that 2 shots of Sinovac can raise specific antibody immunity. The first injection may still show low immunity, but this increases after the second shot. However, the two shots are not enough to stimulate cell immunity. This is the limitation of the inactivated type.

“Therefore, those receiving two Sinovac vaccinations need to receive a booster, especially during the time there are spreads of new species like Delta. This is because the level of antibody built is not enough to protect against new virus species. The government also recommends two shots of different types of vaccine, the first inactivated or Sinovac, and the second being Viral Vector Vaccine or AstraZeneca. Studies abroad showed that AZ can stimulate T cells well. In order to increase the efficiency of two immunities, the third vaccination for people receiving 2 SVs should be the vaccine that increases cell immunity, which is Viral Vector Vaccine or AstraZeneca, or mRNA,” Asst. Prof. Athibodee ended.

News / Photos: Communications Division, Khon Kaen University

[Thai]

 

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