Covid cases are rising in South Africa. But how serious is this and what might it mean for the UK?
What’s happening in South Africa?
The country is seeing a wave of Covid infections linked to two new forms, or “sub-lineages”, of Omicron: BA.4 and BA.5.
Dr Nicole Wolter of South Africa’s National Institute for Communicable Diseases, said the wave was possibly due to BA.4 and BA.5 having mutations in the spike protein, meaning the virus might be able to dodge the body’s immunity to some degree, as well as waning immunity from previous waves.
“In addition, we have had a relaxing of restrictions, as well as moving into winter and therefore experiencing colder temperatures,” she said.
What do we know about BA.4 and BA.5?
BA.4 and BA.5 have now been found in Europe and the UK – albeit it at low levels – as well as other countries.
Wolter said work was ongoing to understand their characteristics.
“While there has been a slight increase in hospitalisations recently, this is from a very low baseline and currently we do not have any evidence to suggest that these new sub-lineages will be more severe than other Omicron sub-lineages,” she said.
Sub-lineages of Omicron include BA.1, which took off in the UK towards the end of 2021, and BA.2, which now dominates in the UK.
Wolter added South Africa had high immunity because of previous infection and vaccination, and this protects against the risk of developing severe Covid with BA.1. “There is currently no indication that this will change with BA.4/BA.5. However, the situation will continue to be monitored closely,” she said.
However, research, not yet peer-reviewed, from a team including Prof Alex Sigal from the University of KwaZulu-Natal, found that unvaccinated people who have previously had BA.1 have little protection against infection with BA.4 or BA.5. By contrast, those who previously had BA.1 and were vaccinated had much better protection.
Another preprint, from a team including Prof Tulio de Oliveira, director of the Centre for Epidemic Response and Innovation at Stellenbosch University, suggests BA.4 and BA.5 have identical spike proteins, and appear to have a similar growth advantage over BA.2 as BA.2 had over BA.1 – although some say it is too soon to estimate this.
What does this mean for the UK?
Wolter noted it was difficult to say how different countries might be affected as they have different levels of immunity.
Indeed the UK had a long BA.2 wave, and has higher levels of vaccination than South Africa.
“South Africa was different, as [it] did not have a second Omicron wave and the previous immunity of BA.1 is probably waning,” said De Oliveira.
Prof Tom Wenseleers of KU Leuven, also pointed to the spread of BA.2 in Europe. “Given that BA.4 [and] BA.5 are genetically very close to BA.2, the hope is that our immunity against infection with BA.4 [and] BA.5 could be somewhat better and that these variants would have a smaller advantage and would cause a smaller wave over here than in [South Africa],” he said.
Prof Christina Pagel of UCL added that the UK was approaching summer, meaning more outdoor mixing and lower levels of transmission, and although Covid restrictions have been removed, there is waning immunity from vaccination, and hardly any community testing.
“I think [it is] very likely [BA.4 and BA.5] will become dominant here,” she said, adding at best it would be a small wave and at worse similar to those of BA.1 and BA.2, noting that could put strain on the NHS, disrupt education and jobs, and cause more long Covid.
What about vaccines?
Prof Sir Andrew Pollard, director of the Oxford Vaccine Group, said vaccinated populations were in a good position as Covid jabs offered long-lasting protection against severe disease, with boosters potentially helpful for those at higher risk – although discussions are needed about the best approach to future boosters.
Prof Tim Colbourn of UCL suggested it would be good to switch to an Omicron-specific vaccine, although current jabs still protect against severe outcomes.
But Pollard noted that the high rate of Omicron infection, and hence immunity against it, means it is increasingly likely that future spread will involve a new variant. “If the new variant was similar to Omicron, an Omicron vaccine might be a rational choice, but it is difficult to predict today which variant will be upon us next and thus not obvious which variant or variants to include in a vaccine,” he said.
What’s next?
According to Wenseleers, the situation in South Africa suggests endemic Covid may involve a significant wave every six months – although the impact may depend on how boosters are rolled out or updated, and levels of natural immunity.
But not everyone agrees.
“While we can so far be sure that Covid is here to stay, it is not yet clear where viral transmission rates will settle in terms of the level, spikiness or frequency of spread,” said Pollard. “We certainly can’t predict a seasonal or periodic pattern yet.”
