'Mulbaeksin' Sinovac Vaccinees' Antibodies Are One-Tenth of Pfizer's

[Image source=Yonhap News]

[Asia Economy Reporter Cho Hyun-ui] The antibody levels of individuals vaccinated with the Chinese Sinovac vaccine, which has been embroiled in controversy as a 'water vaccine,' were found to be one-tenth of those vaccinated with Pfizer.

On the 16th, the Hong Kong South China Morning Post (SCMP) reported, "Researchers from the University of Hong Kong investigated the antibody formation rate after COVID-19 vaccination among 1,442 frontline medical workers," revealing these findings.

Additionally, the antibody levels of Sinovac vaccine recipients were similar to or even lower than those of patients who had contracted and recovered from COVID-19.

The research team collected and analyzed blood samples from medical staff at various intervals. In an initial test involving 93 participants, 63 Pfizer vaccine recipients showed a significant increase in antibody concentration after the first dose, which further increased after the second dose. In contrast, 30 Sinovac vaccine recipients had low antibody concentrations after the first dose, reaching average levels only after the second dose.

Furthermore, in a survey of 12 recipients from each vaccine group, the average antibody level of Pfizer vaccine recipients was 269, approximately 10 times higher than the 27 observed in Sinovac vaccine recipients.

The researchers also noted that the Pfizer vaccine recipient with the lowest antibody level had a higher antibody concentration than the Sinovac vaccine recipient with the highest antibody level.

The preventive effectiveness of the Pfizer and Sinovac vaccines has been reported as 95% and 50.7%, respectively. SCMP stated, "While antibody levels are not directly correlated with immunity, studies continue to show that higher antibody levels generally correspond to stronger responses to COVID-19 infection and longer-lasting immunity."

The research team said, "The difference in neutralizing antibody concentrations between recipients of the two vaccines can be interpreted as a significant difference in vaccine effectiveness." They added, "This suggests that booster shots may be necessary, especially for elderly Sinovac vaccine recipients with weaker immune responses."

According to SCMP, these findings are similar to a study published last month in the Hong Kong Medical Journal by researchers from the Hong Kong Yanghua Clinic. That study surveyed antibodies in 457 medical workers and found that antibody levels in Pfizer vaccine recipients were more than 10 times higher than those in Sinovac vaccine recipients.