KEY POINTS
- A study in China found that SinoVac and SinoPharm were 70% effective in preventing COVID-19 infection
- A prepress study in Brazil found that SinoVac was only 54% effective in preventing coronavirus infection
- Singapore had previously refused to count SinoVac blows in the country’s vaccination count
The Chinese-made COVID-19 vaccine, SinoVac, has been found to produce significantly lower levels of antibodies compared to the vaccine developed by Pfizer-BioNTech, which caused Singapore residents to receive booster shots.
Antibody levels in people who have received two doses of the Pfizer vaccine were typically between 1,300 and 2,000 international units per milliliter. However, the figures are much lower in individuals who received two shots of the SinoVac vaccine.
“For Sinovac, it’s zero to 40. We have a few with 200 to 300,” Dr. Leong Hoe Nam, an infectious disease specialist at Singapore’s Rophi Clinic, told the South China Morning Post.
Dr. Leong noted that lower levels of antibodies in SinoVac receptors have caused an increasing number of individuals to obtain Pfizer as a booster shot.
“They took the Sinovac shots, did the blood test and saw low levels of antibodies and then opted for Pfizer as a third dose,” he added.
A study by researchers in China found that SinoVac and SinoPharm vaccines had a combined 70% effectiveness in preventing an infection caused by the most contagious Delta variant in Guangzhou City. The study, which has not yet been peer-reviewed, also noted that the shots were 100% effective in preventing serious infections and deaths.
However, a Brazilian prepress study comparing SinoVac with the AstraZeneca COVID-19 vaccine found that the receptors for the Chinese-made vaccine had lower levels of protection against the virus.
SinoVac receptors were 54% less likely to contract COVID-19 and 74% less likely to die from the virus compared to unvaccinated. Efficacy decreased in the elderly population, reducing the risk of death by only 35% in people over 80 years of age. In comparison, AstraZeneca reduced the risk of infection by 70% and the risk of death by 90%.
The Singapore government had previously excluded people who received SinoVac shots from the country’s total vaccine count. Health Minister Ong Ye Kung cited inadequate efficacy data as a reason for the move.
“We don’t really have a medical or scientific basis nor do we have the data to establish the effectiveness of SinoVac in terms of infection and serious illness in Delta,” Ong said during a July briefing, according to Reuters.
The Singapore Ministry of Health later announced that it will consider that people who received vaccines included in the World Health Organization’s emergency use list, such as SinoVac, Sinopharm and AstraZeneca, are fully vaccinated, in a effort to be more “inclusive”.
“What is important now is the difference between those who are vaccinated and unvaccinated and less so between the different vaccines,” Ong said at a news conference in early August.
Despite this, the Singapore government still offers third doses of vaccines to residents who had taken the SinoVac jab as part of a “heterologous vaccination strategy”.
“We have not stopped them, although data are still lacking given the effectiveness of this strategy using two different vaccines: we call it a heterologous vaccination strategy,” Kenneth Mak, director of medical services, said during a virtual interview at the door.
