An expert at Chulalongkorn Hospital yesterday warned of a "ticking time bomb" for those who had their second Sinovac vaccine dose some time ago, and recommended booster shots due to a drop in immunity levels.
Asst Prof Dr Opass Putcharoen, head of the Emerging Infectious Diseases Clinical Centre, said research has shown that despite vaccination, people remain at risk of being infected. This group should be the priority for a third dose, which could be of either the AstraZeneca or Pfizer formulas, he said.
Dr Opass, however, pointed out that second doses are the key in the broader fight against infections, so people should not get carried away with the high percentage of first doses. He said it was important that vulnerable groups, especially the immobile and those living in outbreak zones, receive their second shot.
Meanwhile, the Public Health Ministry yesterday signed a contract to purchase another 10 million doses of the Pfizer Covid-19 mRNA vaccine, raising the total to 30 million doses for delivery by the end of this year.
The contract was signed by Dr Opas Karnkawinpong, director-general of the Department of Disease Control (DDC), and Deborah Seifert, Country Manager, Pfizer Thailand and Indochina. It was witnessed by Deputy Prime Minister and Public Health Minister Anutin Charnvirakul, assistant to the PM's Office Minister, ministry adviser Dr Praphon Tangsrikiarttikul and Health permanent secretary Kiattiphum Wongrajit.
The department chief earlier signed a supply agreement for 20 million doses on July 20. Delivery is to be made gradually in the fourth quarter of this year. Mr Anutin said the vaccine would be administered on a voluntary basis.
Dr Opas, the DDC's chief, said more than 500,000 doses would have to be administered on a daily basis for the country to achieve its 70% target by year-end.