In a press statement on Sunday (May 15), MOH said these are the first community cases confirmed to have these two variants, which have been classified as “variants of concern” by the European Centre for Disease Prevention and Control.

“The presence of BA.4 and BA.5 variants in these three cases was detected via further testing of polymerase chain reaction positive samples and confirmed through whole genome sequencing,” said the ministry.

“All cases were either asymptomatic or had mild symptoms such as fever, cough, runny nose and sore throat; and did not require hospitalisation.”

It added that the three infected are fully vaccinated and have received their booster dose. 

They had also self-isolated upon testing positive for Covid-19, and did not have any reported exposure to vulnerable settings.

The BA.4 and BA.5 variants were first reported by South Africa in early 2022, and are dominant variants there.

They have mutations in the spike protein which confer greater “immune escape properties” and higher transmissibility compared to the BA.1 and BA.2 variants causing the Omicron wave in Singapore earlier this year, said MOH.

“However, emerging real-world evidence from other countries supports that BA.4 and BA.5 infections will likely give rise to similar clinical outcomes, compared to previous Omicron lineages.”

According to the World Health Organization, there have been at least 1,000 cases of the two variants reported in at least 16 countries as of May 11.

MOH said: “We will step up local surveillance efforts and continue monitoring the spread of BA.4 and BA.5 in Singapore.

“While our society is now more resilient against the virus, everyone should to continue to play their part and remain vigilant to mitigate the spread of Covid-19.”

The ministry said people vulnerable to complications of Covid-19 — such as the unvaccinated, persons above the age of 60 and those with chronic diseases — should ensure they are up to date with their recommended boosters and exercise caution in settings with potential contacts. 

 - TODAY SG