A new Omicron sub-variant, known as the XBB, has been driving a significant surge in COVID-19 cases in Singapore, local media reported.

The island country in Southeast Asia reported an average of 7,716 local cases per day in the past week, compared with a daily average of 2,000 last month, according to data from Singapore's Ministry of Health (MOH).

On Tuesday, the number of new cases reached 11,732, a recent new high and more than double the previous day's number.

Singapore's Health Minister Ong Ye Kung expected the caseload to further increase to 15,000 cases per day on average, and could even reach 20,000 or 25,000 on some days.

The infections are likely to peak in mid-November, he said on Saturday, noting that "this is likely to be a short and sharp wave."

There has also been an increase in hospitalized cases, but the number of severe cases has remained relatively low, the MOH said, adding it's "very likely due to the resilience built up through vaccination and previous waves of infection."

So what's XBB and how dangerous is the new strain? Here is what we know so far:

What's XBB and where has it been detected?

The XBB is a new Omicron sub-variant, the BA.2.10 strain.

Besides Singapore, it has also been detected in countries such as Australia, Bangladesh, Denmark, India, Japan and the U.S. since August 2022, according to Channel News Asia.

Is it more infectious?

It appears so. Ong said on Tuesday that "XBB is demonstrating characteristics that it is dominating over all other sub-variants," according to Channel News Asia.

He added that the MOH is watching it very closely.

"It has been detected in many parts of the world but in Singapore is rising very fast – within three weeks from nothing, it is now over half of all the daily cases," Ong was quoted as saying.

Does it cause more severe illness?

There is no evidence of XBB causing more severe illness, the MOH said.

So far, the large majority of patients in Singapore continue to report mild symptoms, such as sore throat or slight fever, especially if they have been vaccinated, the ministry said.

How protected are people vaccinated with previous shots?

Previous vaccination schemes of either three complete mRNA shots or four Sinovac doses are "still very effective against preventing severe illness," Dr Leong Hoe Nam, an infectious disease specialist at Mount Elizabeth Novena Hospital in Singapore, told Channel News Asia.

He added that those who are unvaccinated are at risk.