SINGAPORE — Singapore has detected 198 COVID-19 cases – 48 local and 150 imported – infected with the BA.2 Omicron subvariant as of Tuesday (25 January).
In its response to media queries on Friday, the Ministry of Health (MOH) referenced Denmark's recent findings on the subvariant, noting that authorities there had found that BA.2 is more infectious than BA.1 but with no significant difference in clinical outcomes.
The ministry added that it will need further data and study to fully understand the implications for severity, immunity, and transmissibility of BA.2.
Denmark's top infectious disease authority Statens Serum Institut (SSI) had on Wednesday said that preliminary calculations suggested BA.2 could be 1.5 times more infectious than BA.1.
However, an initial analysis by the institute showed no difference in the risk of hospitalisation for BA.2 compared to BA.1.
The main BA.1 Omicron variant currently accounts for 98 per cent of all cases globally but has been replaced by BA.2 in countries like Denmark, where it became the dominant strain in the second week of January.
Worldwide, 18,751 sequences of BA.2 have been uploaded to the Global Initiative on Sharing All Influenza Data (GISAID), the world's largest database of novel coronavirus variants, since 4 January last year.
While it is not clear where the subvariant first emerged, the new strain has been reported in some 50 countries, including Singapore, Denmark, the Philippines, India, and Sweden. The UK Health Security Agency (UKHSA) earlier this week formally designated BA.2 as a “variant under investigation”.
The World Health Organization (WHO) had also this week updated its website to warn that BA.2 "differs from BA.1 in some of the mutations, including in the spike protein" and is increasing in many countries.
“Investigations into the characteristics of BA.2, including immune escape properties and virulence, should be prioritised independently and comparatively to BA.1,” the agency added.
The BA.2 subvariant does not carry a specific mutation present in BA.1 – the deletion of a spike gene – which makes it stand out on polymerase chain reaction (PCR) tests without the need for extra genome sequencing.
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