Respected virus expert Yong Poovorawan insisted mixing and matching vaccines is a safe and effective method for fighting the fast-spreading Delta variant of Covid-19, even after a World Health Organization (WHO) scientist on Monday advised against it.
Using the Sinovac and AstraZeneca vaccines in series is the best solution available right now to combat the rapid spread of the Delta variant of Covid-19, Prof Yong told a press conference at the Public Health Ministry yesterday.
His remark came after WHO chief scientist Soumya Swaminathan advised against people mixing and matching Covid-19 vaccines from different manufacturers, calling it a "dangerous trend" since there is little data available about the health impacts.
"We are in a data-free, evidence-free zone as far as mix and match," Ms Swaminathan told an online briefing on Monday.
"It will be a chaotic situation in countries if citizens start deciding when and who will be taking a second, a third and a fourth dose," she added.
She also tweeted: "Individuals should not decide for themselves, public health agencies can, based on available data. Data from mix and match studies of different vaccines are awaited -- immunogenicity and safety both need to be evaluated."
At the press conference yesterday, Prof Yong, also the government's adviser on the Covid-19 pandemic, explained that two doses of Sinovac were not enough to prevent infection by the Delta variant.
With AstraZeneca, the 12 weeks allowed between first and second doses were a long time to wait. That led to studies of injecting the inactivated virus of the Sinovac vaccine in the first dose to be followed soon by the second dose of AstraZeneca. The studies were put into practice and it was found that the cross-vaccination was able to spur body immunity higher and faster than anticipated, Prof Yong explained.