Over 80% of Thais have 'hybrid immunity' against Covid-19: virologist


More than 80% of the Thai population has developed “hybrid immunity” to the Covid-19 virus from a combination of vaccination and infection, Professor Yong Poovorawan said on Saturday.

More than 70% of the Thai population, or over 50 million people, were infected with Covid-19, while at least 80% of the population has been fully vaccinated (with at least two doses), the virologist wrote in a Facebook post.

“So, most of the population – over 80% – have developed hybrid immunity, which helps lessen the severity of disease, covering new mutations like XBB.1.5, which is expected to arrive soon,” the virologist wrote.

Hybrid immunity can protect against Covid-19 better than vaccination or past infection alone, he added.

Prof Yong leads the Centre of Excellence in Clinical Virology at Chulalongkorn University’s Faculty of Medicine.

New Covid-19 variants tend to be less severe than in the past, he said, explaining that it was the nature of viruses to become less severe as they evolve because they have to rely on living carriers for their survival.

He said that after a series of mutations, new Covid-19 variants have constantly caused less severe symptoms. Globally, the fatality rate of Covid-19 has fallen from 3-5% at the outset of the pandemic to less than 1% now.

In Thailand, the fatality rate has dropped from 1% when it became an epidemic here, to less than 0.1% now, Yong said, adding that for healthy people, catching Covid-19 was now no different from getting the flu.