The Ministry of Public Health on Sunday insisted that CoronaVac, the vaccine developed by Chinese company Sinovac Biotech Ltd, could protect people against COVID-19, despite a claim on social media that a man who received the jab had not developed any immunity.
“The immunity develops two weeks after you have had your shots,” said Dr Supakit Sirilak, chief of the Department of Medical Science (DMS) in response to concerns over the efficacy of the vaccine. “However, the level of immunity differs based on the virus variants.”
Many people have responded to one man’s claim that he received the state-sponsored jab and then bought a rapid test which showed he hadn’t developed any immunity at all. Dr Sirilak said anyone wanting to check the efficacy of their jabs should only have their immunity checked by standard laboratory tests.
“I am not surprised to see that the rapid test could not detect the immunity because it couldn’t reach the point where the immunity is found, which is spike protein,” said Dr Sirilak, who said he had had the Chinese vaccine in February and had developed immunity two weeks after the second jab. “It needs to be done under standard laboratory conditions with a proven method,” he added.
Dr Sirilak said Sinovac’s vaccine performed best with a level of immunity at 114 against the original strain from China’s Wuhan – but its efficacy dropped to less than half that level when measured against the mutated G strain that is now spreading around Thailand.
He also quoted research of CoronaVac’s efficacy in Chile showing that the level of immunity increased by 47.8% when tested 14 days after two shots but was as high as 95.6% after 70 days.
Sinovac’s vaccine is 67% effective in preventing symptomatic COVID-19 infections and prevents 80% of fatalities, according to a Bloomberg news report this week, citing a Chilean government study published on Friday.
Dr Sirilak said the DMS had been monitoring vaccines’ efficacy against COVID-19 variants, with special attention given to variants from South Africa and India.
Meanwhile, Dr Opas Karnkawinpong, chief of the Department of Disease Control, said his staff had found that infections from the latest Thong Lor cluster were predictable and one person could spread the disease to 1.6 people.
That means the number of new infections will be reduced within two weeks if people comply with the government’s measures, including the closure of pubs, a ban on mass gatherings and drinking alcohol in restaurants.