In South Africa, there has been a rapid increase in the number of infections with two new subtypes of the Omikron variant of MERS-CoV over the past two weeks. These are the types BA.4 and BA.5. They seem to escape defenses against the former subtype circulating in South Africa (BA.1). Virologists have been monitoring variants closely for weeks, but until recently there was no reason to raise alarm. In South Africa, infections have not led to an increase in hospitalizations or deaths from Covid-19 until recently. But hospital admissions in some South African provinces have been on the rise over the past week, according to a report by bioinformatician Tulio de Oliveira, director of the Center for Epidemic Response and Innovation at Stellenbosch University in South Africa. The number of recorded infections in South Africa is now back to the same level it was at the beginning of December, just before the fourth wave.
“Alert is an important word, but these subvariants clearly have some advantages,” says virologist Marion Koopmans of Erasmus MC. “It looks like they’re going to create a new wave in South Africa.”
Since the discovery of the Omikron variant of the coronavirus in South Africa on November 26, it has replaced all other types around the world. Omikron is more contagious than the previous variants and partially escapes previously created defenses. There were initially three subtypes, BA.1, 2 and 3.
In South Africa, it is estimated that at least 90% of the population has acquired immunity to the coronavirus – some through vaccination, but the vast majority of people have had a previous infection. But after three months, the strength of that defense waned – it is no coincidence that the spread of the new subspecies began about four months after the start of the fourth wave in South Africa, caused mainly by BA.1.
As the two new subtypes BA.4 and BA.5 also appear to evade the immune system due to the new mutations, they are now rapidly gaining a foothold in South Africa. Will The severity of BA.4 and BA.5 varies by country or regionIn De Oliveira’s opinion, depending on how you build defenses on the spot.
Scientists are trying to find out how soon these new subtypes escape the immune system, and whether they are more troublesome than the previous subtypes of Omikron. South African virologist Alex Segal published the first data on the immune system this week in a preliminary edition. This gives the impression that the virus neutralizing antibodies that people (unimmunized) develop after infection with BA.1, are more than seven times less effective against BA.4 and BA.5. The antibodies of vaccinated people (with Pfizer or Janssen) who had BA.1 infection were furthermore better: they worked three times less.
Researchers are still not sure how exciting the two new BA.4 and BA.5 subtypes will be. “The first subtypes of Omikron were distinctly milder than the previous variants, Alfa, Beta and Delta,” says Koopmans. “It is not yet clear whether these new subtypes are comparable to the first Omikron, Alfa or Delta. This question is becoming increasingly difficult to answer, because the circulating variables and the defense structure differ in each country.”
Small numbers of these BA.4 and BA.5 subtypes have already been selected in more than twenty countries, including Australia, the United States, China, Israel, Austria, Belgium, Germany, France, Denmark, and the United Kingdom. In the Netherlands, they are not yet found in the weekly samples of general practitioners and test streets, BA.5 was found once in early April in another study. In our country, BA.1 was distributed mainly in December and January, the BA.2 subtype has been dominant since mid-February.
We’ll have to wait and see what BA.4 and BA.5 will mean in Europe and the Netherlands, Koopmans says. “It is too early to make any statements about that.”
The source of the new subspecies remains a mystery. “They did not originate from the previous subspecies of Omikron, but they all seem to have evolved from the same source. This could be, for example, a person with a poor immune system and therefore a long-term carrier of the virus, or a certain animal species,” says Koopmans.
Never a dull momentKoopmans says. But it emphasizes once again that we really need long-term plans. We’ve just scaled back our testing and monitoring, which isn’t wise. I also really want to get rid of it, but this virus continues.”
Read also: Omikron: As contagious as measles, but not too sick – for now (January)
A version of this article also appeared in May 4, 2022
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