Those with no Covid-19 history or who have recovered from the virus more than seven months ago may be at a higher risk of being infected with the XBB Omicron Covid-19 subvariant, according to Health Minister Ong Ye Kung.
Infections predominantly of XBB subvariant
Speaking at the Ministry of Health press conference on Oct. 15, Ong noted that the number of Covid-19 cases has been on the rise as a result of the Omicron XBB subvariant.
XBB is now the predominant subvariant that is circulating in Singapore, and accounts for 54 per cent of local cases for the week from Oct. 3 to 9.
This is a 32 per cent increase from the 22 per cent recorded the previous week.
XBB driving re-infections
Ong added that there is evidence that the XBB subvariant may be driving an increase in re-infections.
The proportion of re-infections among the total number of Covid-19 cases in Singapore has been increasing over the past month, with re-infections currently making up about 17 per cent of total new cases.
Ong said on Oct. 11 -- four days ago -- that as many as 15 out of 100 cases in Singapore have been those re-infected with Covid-19.
Those more likely to be at risk
Ong said individuals with no history of Covid-19 may face a higher risk of catching the XBB Omicron subvariant.
The rate of those who have never been infected with Covid-19, referred to as "Covid-naive" by MOH, is 162.5 infections per 100,000 person-days from Oct. 8 to 14.
This is higher than the respective incidence rates of those who have previously caught the virus during the Delta and the more recent Omicron wave.
The incidence rate of those who were previously infected during the recent Omicron wave was 42.4 out of 100,000 from Oct. 8 to 14, of which those who recovered from the virus for more than seven months are at higher risk of being re-infected.
These individuals at higher risk of being re-infected have an incidence rate of 70.9 out of 100,000.
Those who were infected and recovered from the virus four to six months ago have an incidence rate of 26.4 out of 100,000 during the same time period.
Additionally, the incidence rate of those who caught the Covid-19 virus before or during Singapore's Delta wave -- which peaked between October and November 2021 -- is at 147.4 out of 100,000 from Oct. 8 to 14.
Ong said individuals who have recently been infected and recovered within the past one to three months is "very rare", where the incidence rate is 0.7 out of 100,000 from Oct. 8 to 14.
Peak by mid-November 2022
Ong said the number of Covid-19 cases in Singapore may reach 15,000 next week, and may even hit 25,000 during "abnormal" days such as Tuesdays when cases are typically higher after the weekend.
However, he added that the wave will likely peak by around mid-November 2022.
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