Study finds vaccines to be effective

19 May 2021

Both the Sinovac Covid-19 vaccine from China and the AstraZeneca formula have been shown to boost antibody responses in almost all vaccine recipients.

This was the outcome of a study conducted by Chulalongkorn University's Center of Excellence in Clinical Virology and the Faculty of Medicine.

Prof Sirirerk Songwilai said the permanent secretary of the Higher Education Science Research and Innovation Ministry, up to 97.26 per cent of people receiving the AstraZeneca vaccine developed immune responses in tests conducted four weeks after their first shot.

He said no test results after the second injection were included in the study as they had not yet been finished at the time.

In terms of the Sinovac vaccine's efficacy, he said that the study found that 99.49% of recipients had antibody responses four weeks after their second injection even though only 65.9% developing immune responses three weeks after the first dose.
Antibodies to SarsCoV2, the new coronavirus that causes Covid-19, were measured in human plasma or serum specimens using the Roche Elecsys Electrochemiluminescence Immunoassay (ECLIA), which is a qualitative detection of total antibodies developed against Sars-CoV-2.
In the case of the AstraZeneca vaccine, blood samples were drawn from both the control and experiment groups for antibody response testing before the vaccination injection and again four weeks after, he said.
The Sinovac vaccination group received the same pre-vaccination antibody test, and more antibody tests would be carried three weeks after the first dose and four weeks after the second shot, he said.
Natural antibody responses to coronavirus were examined to immune responses induced by the vaccinated groups in a group of 263 Covid-19 infected patients, he said.
According to Prof Sirirerk, only 243 (92.4%) of the 263 infected patients developed antibodies against the coronavirus.
When the AstraZeneca group was broken by gender, all 42 female vaccine recipients and 29 out of 31 male vaccine recipients (93.5%) developed immune responses four weeks after the first shot.
When analyzed by age, however, all 44 vaccine recipients in the same AstraZeneca group aged 18 to 59 years old developed antibody responses.
Three weeks after the first shot, 124 out of 188 vaccine recipients (65.9%) developed antibody responses in the Sinovac vaccine group.
According to him, the AstraZeneca and Sinovac vaccines were both highly effective in boosting immune responses against the new coronavirus.
Despite its apparent low efficacy after the first round of injections, Prof Sirirerk stressed that the Sinovac Covid-19 vaccine's high efficacy in boosting antibodies against SarsCoV2 was only proven after both jabs had administered to the test subject.