Singapore — While many Singaporeans opted to pay for their Sinovac Covid-19 vaccines instead of getting free mRNA jabs, a decrease in their antibodies against infection has prompted some to seek booster shots from Pfizer or Moderna.
Tests administered to people who received China-made Sinovac jabs, which uses an inactivated virus containing Sars-CoV-2 spike proteins that teach the body’s immune system to create antibodies against the virus, show decreased levels of protection in comparison to mRNA shots from Pfizer and Moderna.
A recent article in the South China Morning Post (SCMP) quotes infectious diseases specialist, Dr Leong Hoe Nam, as saying that more and more people are discovering that Sinovac jabs offer inadequate protection.
“They took the Sinovac shots, did the blood test and saw low antibody levels, then opted for Pfizer as the third dose,” said Dr Leong.
People who have received two doses of the Pfizer vaccine have antibodies between 1,300 and 2,000 international units per millilitre, but some of those who received the Sinovac shots have levels of “zero to 40,” he added, and “a few with 200 to 300.”
Those who opted for the Sinovac shots may still avail of the government-administered mRNA shots, said the health ministry’s director of medical services, Dr Kenneth Mak, even if studies are still incomplete concerning the effectiveness of mixing vaccines.
As of Aug 28, over 4.4 million people in Singapore, or 80 per cent of the population, are fully vaccinated against Covid-19. Among them, over 85,000 people received Sinovac jabs. SCMP reports that “an estimated 460,000” have yet to be inoculated against Covid-19.
This week, a fourth vaccine, Sinopharm, also manufactured in China, begun to be administered to those who want it.
The Sinopharm vaccine is said to have a higher efficacy rate (79 per cent) than Sinovac (51 per cent) and had its first day of use in Singapore on Monday (Aug 30) for a trial run.
According to reports, the demand for Sinopharm has been high.
SCMP quotes an associate professor at the National University of Singapore’s Saw Swee Hock School of Public Health, Dr Jeremy Lim, as saying that for some, the reality that vaccines are “pretty much essential” to reduce severe Covid-19 is sinking in.
“Hence, it’s really about which vaccine best fits one’s world views and concerns, no matter how justified or otherwise.
The clamour for the Chinese vaccines is thus understandable given the imperative for vaccination,” said Dr Lim.
However, the complexity of the immune system means that the level of antibodies does not automatically ensure how protected a person is from infection.
But as for now, even with minimal guidance concerning booster shots, those who remain concerned about waning antibody levels may avail of further doses. /TISG
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