The Centre for Covid-19 Situation Administration (CCSA) has a lot of explaining to do over why another 12 million doses of the Sinovac vaccine were included in its August-September Covid-19 jabs procurement plan.
CCSA spokesman Dr Taweesilp Visanuyothin said on Monday that the centre's board chaired by Prime Minister Gen Prayut Chan-o-cha had approved a proposal to secure at least 10 million doses of Covid-19 vaccines for September.
The plan is to cover vulnerable groups -- the elderly, people with underlying diseases and pregnant women -- as quickly as possible in order to reduce the number of fatalities.
The centre has an ambitious plan to inoculate at least 70% of the elderly in every province by next month.
That is apart from giving a second dose to those who have received their first one, providing vaccine coverage in areas where new clusters break out and where tourism and economic recovery activities are planned.
There are no questions about the validity of the plan. At present, there is no other way to curb the Covid-19 pandemic except by mass vaccination.
Since new infections have shown no signs of slowing down despite weeks of semi-lockdown, the quest for more Covid-19 vaccines has become even more urgent.
What is questionable, however, is the CCSA's decision about which vaccines it will procure next.
According to the spokesman, the CCSA endorsed the proposal by the Public Health Ministry to reserve another 10 million doses of Pfizer shots, procure another 12 million doses of Sinovac and find another 10 million doses of other brands of Covid-19 vaccines this year.
But why do we need to buy more Sinovac?
In justifying its vaccines procurement proposal, the Public Health Ministry said the jabs are urgently needed to fight the predominant Delta variant which is spreading fast in the country.
But the ministry knows the efficacy of Sinovac vaccines remains in doubt against the Delta strain. That is why it switched from two doses of Sinovac to a mix-and-match formula using the Sinovac vaccine as the first dose to be followed by AstraZeneca as the second dose.
The formula is the first of its kind and has not been adopted anywhere else in the world.
While the Public Health Ministry said the results have been satisfactory with people receiving the mix-and-match formula showing a high level of immunity in a short period of time, the long-term efficacy and practicality have yet to be confirmed as the rollout only started in late July.
An article by Thai doctors published in medRxiv highlighted a low level of neutralising antibodies generated by Sinovac when compared to natural infection. It suggested that booster doses beyond the conventional two-dose regimen may be needed to maintain the immune response.
The question then is if the efficacy of Sinovac against the Delta variant, presently found in more than 90% of the new infections in the country, remains in doubt, why would we want to buy more?
If we take into account the cost-effectiveness, why should the country spend money on vaccines that may or may not work against the prevailing Covid-19 variant, which also most likely require booster doses which will in turn cost the country more to procure?
Why didn't the CCSA opt for mRNA vaccines for its future procurement plan? Why does it stick to Sinovac despite its debatable qualities? The CCSA owes the public a detailed explanation.