New Covid-19 variants emerge: Should South Africans be concerned?

Concerns about new Covid-19 variants are on the rise globally, with an increase in hospital patient cases reported in the UK and the US. 

The new variant has been called Stratus (also known as XFG) and is a recombinant variant. This means it combines genetic material from two earlier strains: F.7 and LP.8.1.2.

XFG is notable for its mutations that may help it evade the immune system.

In the UK, Covid cases among hospital patients have seen a notable increase, jumping by almost a third in just two weeks.

The positivity rate for respiratory symptoms in hospital patients rose from 5.8% on July 26 to 7.6% on August 10, marking a 31 per cent increase in 15 days, according to the UK Health Security Agency (UKHSA).

In simpler terms, more hospital patients who showed cold or flu-like symptoms tested positive for a virus. The rate went up from about 6 out of 100 patients on July 26 to about 8 out of 100 patients on August 10. That’s a 31% jump in just over two weeks.

This surge has prompted warnings of a potential new wave of infections. 

In June, the SARS-CoV-2 variant, NB.1.8.1, also known as Nimbus, is an Omicron-descendent lineage derived from the recombinant variant XDV.1.5.1.

It was first detected in Asia in January 2025 and designated a Variant Under Monitoring (VUM) by the World Health Organization (WHO) on 23 May 2025.

Globally, NB.1.8.1 has shown increasing prevalence, rising from 2.5% of sequences submitted to the Global Initiative on Sharing All Influenza Data (GISAID) in late March 2025 to 10.7% in late April 2025.

As of May 18, 2025, it had been detected in 22 countries and was associated with an increase in SARS-CoV-2 infections in parts of Asia.

Preliminary data indicate that the NB.1.8.1 variant has mutations in its spike protein that may increase its transmissibility and result in marginal immune evasion compared to other circulating variants.

However, current data do not indicate that NB.1.8.1 is associated with increased severity or different symptoms. The WHO assessed the public health risk of NB.1.8.1 as low as of 23 May 2025, and current COVID-19 vaccines are expected to protect against severe illness from this variant.

South Africans can take comfort in the fact that, as of June 10, 2025, the NB.1.8.1 variant had not been detected in the country through clinical surveillance, despite limited SARS-CoV-2 testing and specimen submissions for sequencing. Furthermore, current reports indicate that there is no cause for concern regarding the Stratus variant either.

Data from South Africa's respiratory illness syndromic surveillance programmes show that the number of SARS-CoV-2 infections is currently low. While the severity of the NB.1.8.1 variant in South Africa is presently unknown, it's believed that high levels of immunity to SARS-CoV-2 in the country may lead to a less severe course of disease in infected persons.

Key recommendations include:

• Practising regular hand washing and good hand hygiene.
• Covering coughs and sneezes.
• Avoid contact with people who may be at high risk of severe respiratory illness when unwell.
• Maintaining distance from others when ill.
• Wearing a mask when appropriate, especially around individuals at higher risk of severe disease.
• Monitoring of SARS-CoV-2 variants continues in South Africa as part of national syndromic surveillance and through the Network for Genomic Surveillance in South Africa (NGS-SA).

IOL