Hong Kong Researchers: Pfizer Booster Shot Effective After Sinovac Vaccination

[Image source=EPA Yonhap News]

[Asia Economy Reporter Hyunwoo Lee] Researchers in Hong Kong have announced a study showing that individuals with low antibody levels after receiving the Chinese Sinovac COVID-19 vaccine can significantly boost their immunity by receiving a booster shot of the U.S. Pfizer vaccine.

According to the South China Morning Post (SCMP) on the 4th, researchers from the University of Hong Kong and the Chinese University of Hong Kong jointly published a report stating, "Our study shows that for people who previously had a poor response to the Sinovac vaccine, a Pfizer booster shot increases immunity much more than a Sinovac booster shot."

This study, supported by the Hong Kong government, was conducted from August to October on 80 individuals aged 34 to 73 with low antibody levels after receiving the Sinovac vaccine. The researchers divided them into two groups of 40, administering either the Sinovac or Pfizer vaccine as a booster shot, then measured antibody levels and effectiveness against variant viruses one month later.

The results showed that those who received the Pfizer vaccine as a booster had a 95% effectiveness against variant viruses, while those who received the Sinovac booster showed 48% effectiveness. The researchers reported that the Pfizer booster provided protection rates of 95.33%, 92.51%, and 92.29% against the Delta, Gamma, and Beta variants of COVID-19, respectively. In contrast, the Sinovac booster group showed protection rates of 48.87%, 32.22%, and 38.79% against the same variants.

However, recipients of the Pfizer booster reported more swelling and discomfort at the injection site, as well as fatigue and muscle pain, compared to those who received the Sinovac booster. The researchers explained that these side effects were mild and short-lived.

SCMP noted, "This study found that the Pfizer vaccine produces significantly more specific neutralizing antibodies against the more contagious Delta variant than the Sinovac vaccine," adding, "This may encourage Hong Kong residents to choose the Pfizer vaccine as their booster shot."

Earlier, in March, Regina Ip, chairwoman of the pro-Beijing New People's Party and a prominent pro-China politician in Hong Kong who completed Sinovac vaccination, revealed in September that her COVID-19 antibody test showed 'zero,' prompting her to receive a Pfizer booster shot. Senior Hong Kong government officials and pro-Beijing politicians received the Sinovac vaccine in February and March.

In September, Hong Kong authorities conducted booster shot trials on 84 individuals who had received the Sinovac vaccine but showed insufficient antibody levels in tests.

Meanwhile, starting from the 11th, Hong Kong will administer COVID-19 vaccine booster shots to the elderly and vulnerable groups. Residents can choose between the Sinovac and Pfizer vaccines for their booster shots.

In Hong Kong, with a population of 7.5 million, residents have been able to choose between the Sinovac and Pfizer vaccines since late February, and the eligible vaccination age was expanded to 12 years and older in June. As of the 3rd, the Hong Kong government reported that 4.6 million people have received at least one dose of the vaccine, representing 68.7% of the eligible population.

This content was produced with the assistance of AI translation services.