BA.2 now dominant Covid strain in Thailand, says senior health official


The BA.2 subvariant of Covid-19 Omicron variant accounts for nearly 52 per cent of current infections in Thailand, said Department of Medical Sciences (DMS) director-general Dr Supphakit Siriluck.

BA.2 has been nicknamed the “stealth variant” for its ability to avoid detection via RT-PCR tests. Studies have also found it spreads 1.4 times faster than the BA.1 subvariant, although the severity of symptoms from infection is the same.

The World Health Organisation (WHO) reported that BA.2 subvariant has a higher degree of transmission to household members, at 39 per cent compared to 29 per cent for BA.1.

The latest DMS survey of Covid-19 found that 99.63 per cent of 1,905 samples were caused by the Omicron variant, while only seven people sampled had Delta.

“We tested 1,802 Omicron patients and found that 51.8 per cent have the BA.2 subvariant,” said Suphakit. “In the following weeks the ratio could grow bigger as the BA.2 is more transmissible than other subvariants.”

Suphakit added that 28.57 per cent of those who have BA.2 had previously contracted Delta and recovered.

“This shows that natural immunity after recovery from Delta variant is not effective against Omicron BA.2.”

“As for the resistance to Covid-19 vaccine, studies have found that the BA.2 subvariant is only marginally more resistant to the vaccine compared to BA.1. The difference has no statistical significance, therefore getting vaccinated is still an effective method of fighting BA.2,” said Suphakit.