UKHSA is watching Omicron variants BA.4 and BA.5 as South Africa reports growing cases and rising hospital admissions
One of the first countries to detect early cases of Omicron late last year could now be on the cusp of another Covid-19 surge.
South Africa is seeing a rise in coronavirus cases, this time being driven by two new Omicron variants named BA.4 and BA.5, with early data suggesting a higher reinfection rate for people who have already had the virus while a slight increase in hospital admissions has also been noticed. So what could this mean for the UK?
What do we know about BA.4 and BA.5?
South Africa, alongside Botswana, were among the first countries at the end of 2021 to detect early cases of Omicron and warn of its potential to spread rapidly - albeit initial signs were that the illness could possibly be milder than previous variants we'd seen up until then.
And as we know, not long after that, and despite a rapid change to travel rules to slow its spread, significant Omicron waves soon took off around the globe as we entered 2022.
There are two new Omicron variants now spreading in South Africa, which the UK Health Security Agency says in its latest report may be associated with the current increase in cases being recorded in the country.
There is evidence, it says, that the variants have a 'growth advantage' compared to previous strain Omicron BA.2 and as of the end of April, weekly cases in the country were doubling while the positive test rate is also on the rise.
Have the new variants made it to the UK?
In its latest technical briefing the UK Health Security Agency comfirms that several cases of BA.4 and BA.5 have now been detected in the UK.
As of May 2, there were 21 confirmed cases of BA.4 and 19 of BA.5 in England. Albeit with testing rates now at some of their lowest since the start of the pandemic - the actual numbers circulating within communities of both variants could be much higher.
There are also small numbers of cases in other parts of Europe but there is no other country at the moment, say health officials, that is showing 'clear growth advantage as yet'.
Why are the new variants being watching so closely?
Viruses mutate constantly and after two years of the pandemic we know that new variants of Covid-19 are not an unusual occurrence. That said, health officials will keep an eye on any emerging new strains to asses the threat they may pose to our existing vaccines and the immunity populations have built up through both vaccination and prior infection.
There is some early evidence that BA.4 and BA.5 could be more capable of reinfecting people who have already had coronavirus and in particular people who have already had a different version of Omicron. This might make previous herd immunity less helpful and less of a protection to fall back on if the variant were to take off in significant numbers.
While cases of these two new variants are no doubt on the rise in England and there is some evidence of international spread - differences in testing and sequencing across countries might not be portraying the most up to date or accurate picture just yet.
Could the situation in South Africa be reflected here?
While cases are on the rise on South Africa - and there is no doubt its early warnings and predictions about the emergence of Omicron did go on to play-out on cases around the world - it is too early to tell whether any South African surge will be reflected in other countries in the coming months.
Officials at the UKHSA say it should be noted that the country has a different background population immunity to the UK, which might mean the viruses play out differently in communities here.
And while the conditions favouring BA.4 and BA.5 point to growth in South Africa, these too might not be replicated elsewhere. For example the southern hemisphere is heading towards winter, while the UK is approaching summer where it is hoped climate changes and subsequent lifestyle changes will encourage a drop in Covid-19 infections rather than any rapid rise.
But those tasked with keeping track of emerging infections insist work is happening at a fast pace to see what risks, if any, BA.4 or BA.5 pose.
Dr Meera Chand, Director of Clinical and Emerging Infections at UKHSA, said: "UKHSA continues to monitor and study variants of SARS-CoV-2 closely and is working with academic partners to rapidly assess the significance of the lineages BA.4 and BA.5.
"Our continued genomic surveillance allows us to further investigate variants that are growing within the UK.