South Africa has been advised to ramp up its Covid-19 testing after the first case of a new Omicron subvariant, XBB.1.5, was detected last week.

The advice, from scientists and the World Health Organisation (WHO), comes on the back of climbing Covid-19 cases in China and the US.

In a briefing on Tuesday, Health Minister Joe Phaahla said President Cyril Ramaphosa and the National Coronavirus Command Council had signed off on a decision to refrain from implementing restrictions on travellers from affected countries, such as China and the US, and no restrictions would be placed on South Africans.

Phaahla added the health department had been monitoring international developments with the virus, amid a 25% increase in global cases in December.

He said more than 14-million new infections were recorded worldwide in December, with 70% of all cases recorded in China, the US, South Korea, Japan, and Brazil.

This has led to a 12% increase in fatalities globally in December, compared to the previous month.

Phaahla added the number of new infections had slowed in the last week of December, except for in China where positive cases increased by 45% and fatalities by 48%.

He said there had been reports of "overburdened" hospitals and crematoriums.

"This is what has caused a lot of panic. A lot of countries imposed special requirements for travellers coming from China," added Phaahla.

He said the wave of positive cases had been driven by the recent easing of restrictions in China, the large population, and low levels of immunisation against the virus.

The high levels of immunity in the South African population prompted the decision to refrain from implementing restrictions on Chinese travellers, as well as other countries experiencing a surge in cases, such as the US.

The health minister added the outbreak in China was not being driven by the XBB.1.5 subvariant, although it appeared to be driving the increase in cases in the US.

The subvariant was detected in South Africa on Friday, News24 previously reported.

Phaahla said the variant of concern that remained dominant in South Africa was still Omicron (accounting for more than 97% of all cases).

While different subvariants have shown different levels of transmissibility, there had not been any marked change in terms of the severity of illness in those infected with XBB.1.5, he added.

"We believe that the dominant variant in the world remains Omicron and that immunity of South Africans from natural immunity and vaccination is still very strong."

Phaahla said the department had consulted with scientists and organisations such as the WHO and had been advised there was no need to impose any travel restrictions on any country, nor was there a need to impose any restrictions internally.

He added the department had been advised to increase the rate of testing and number of samples sent for genomic sequencing.

The department will also increase its surveillance of wastewater to monitor the prevalence of Covid-19 in the population and would extend this surveillance to international flights from countries of concern.

The advice given to the department included "reinvigorating" its vaccination campaign.

"Vaccination remains the bedrock to protect us against any subvariant, and not travel restrictions, at this stage," said Phaahla.