Up to 70% of the population of Thailand may have been infected with COVID-19, as most cases have not been officially recorded because they were asymptomatic or had only mild symptoms, according to Dr. Yong Poovorawan, head of the Centre of Excellence in Clinical Virology at the Faculty of Medicine at Chulalongkorn University.

He said that the estimated infection rate is based on the assessments of blood tests conducted so far, adding that the Omicron variant has spread widely in the past several months, but most of people did not report their infections to health authorities because they had no or only mild symptoms and only those admitted for treatment at hospitals have been recorded.

He said, however, that the Disease Control Department, with funding from the Health Systems Research Institute (HSRI), will conduct an extensive survey to determine the extent of COVID-19 infection in the Thai population, using blood tests to find traces of infection or developed resistance through anti-nucleocapsid and anti-spike IgG tests.

The first such survey will be held in Chon Buri province in October, in cooperation with the provincial health office, among 1,200 samples aged from six months, after which the survey will be expanded to other provinces within six-months.

Results of the survey, said Dr. Yong, will be helpful in the planning of measures to deal with COVID-19 in the future, especially in determining whether further booster doses will be needed.