12 July 2024

Thailand’s well-known and respected virologist Dr. Yong Poovorawan said today (Thursday) that Thailand needs all brands of COVID-19 vaccines it can procure, to inoculate people as quickly as possible.

In his Facebook post today, he explained that the efficacy of all the vaccines, manufactured by various pharmaceutical companies, cannot be compared to each other because they were not researched or tested in the same venue and at the same time, adding that efficacy depends on many factors.

Dr. Yong said that, if the research was under way at a time when there was high incidence of infections, the efficacy of the vaccine would be low, as he cited the case of Pfizer’s version compared to that of Johnson & Johnson.
He also cited a study into the use of the Chinese-made Sinovac vaccine in Brazil, saying that, if the number of mild cases, or those who didn’t need medical attention, were included in the study, the efficacy of the vaccine would be low.

If, however, there were more severe cases, like Grade 4 and upward, the efficacy of the Sinovac vaccine would be higher, even up to 100% for Grade 7 severe cases, he said.
The World Health Organization has graded the severity of COVID-19 into seven levels, with most cases being Grade 3, or out-patients, who do not need to be hospitalized but do need medical attention.  Grade 7 are those with life-threatening conditions.

Dr. Yong further explained that the Pfizer and Moderna vaccines were researched and studied before Johnson & Johnson’s and they appear to be more effective, because the virus has mutated and has reduced the efficacy of the Johnson & Johnson version.

He said that different makes of vaccines cannot be compared because of the mutations of the virus, with the new variants capable of evading the effects of some of them.
He cited the latest report about the Pfizer vaccine, which was found to have 20% lower efficacy against the South African and Indian COVID variants.

Nonetheless, mRNA vaccines generate more antibodies than the other vaccines, he said.