What exactly is ‘BA.2’?
Soon after the discovery of the omikron variant, it became clear that there are in fact three omikrons, technically numbered BA.1, BA.2 and BA.3. The variant that has been taking the world by storm since December is BA.1. But the BA.2 variant appears to be 1.5 times more contagious, according to initial estimates.
And so BA.2 advances. The variant has now been identified in 69 countries, and in many countries it is displacing the BA.1 omikronviruses simply because it reaches more pharynx. In our country, about 36 percent of all infections are of the BA.2 type, according to calculations by the RIVM. It is expected that at the beginning of March it will only be BA.2, which is the clock.
The newcomer also has a nice nickname: ‘snelomikron’, or the ‘shadow variety’. That has a technical reason. The first omikron variant stood out because it happens to give a certain error message in some PCR tests. BA.2 does not give that error message, however. In the test lane it just looks like the delta variant. Only when you genetically turn it inside out, you recognize it as an omikron.
How exactly does BA.2 differ from the first omikron variant?
Seen from a distance, BA.2 is simply an omikron variant, says professor of coronavirology Eric Snijder (LUMC): a coronavirus that enters cells in a somewhat different way, does more in the throat than in the lungs – and probably for that reason less sick. makes. ‘If we look back ten years from now, we will probably say that the emergence of omikron was the first really major change in the virus,’ says Snijder.
Nevertheless, BA.2 differs in twenty points from the omikron variant as we know it. Many of those changes are in auxiliary proteins that the virus uses to replicate itself. ‘But it is very difficult to determine exactly what all those changes do individually. I think we have to accept that we will never know for sure’, says Snijder.
Does BA.2 give other symptoms than ‘normal’ omikron?
It doesn’t seem like that. In countries where BA.2 has been around for some time, such as Denmark and the United Kingdom, BA.2 appears to be just such a virus as omikron: a germ that can cause flu, with remarkably often headaches, colds, fatigue and sore throats as symptoms. However, it rarely results in hospitalization or ICU admission – least of all in people who have been vaccinated.
Can you now also get BA.2-omikron after ‘normal’ omikron?
Left and right there are anecdotes of people who, having just recovered from corona, test positive again, sometimes after a few weeks. In such cases, however, it is more likely that the infection was not completely gone. In any case, there are no indications that BA.2 can reinfect people who just had BA.1.
That wouldn’t make sense either, says Snijder. You would almost forget it because of all the variants, but in the end it is still the same coronavirus. Anyone who becomes infected builds up protection against corona that is broader than against the variant in question alone.
How well do vaccines and boosters work against BA.2?
In Denmark there were indications that vaccines work slightly less well against BA.2. Those infected with BA.2 subsequently infect more vaccinated housemates on average than those who take the ‘regular’ omikron virus home.
But that could also be a coincidence, says epidemiologist Mirjam Knol (RIVM). In Great Britain, such a difference in vaccine protection was again not seen. There is also a caveat to such observations: the variant is still new. ‘First estimates may be biased’, says Knol.
This does not alter the fact that all omikron viruses, including BA.2, can infect people who have been vaccinated or recovered from corona. To be precise: those who have been vaccinated have only 10 percent less chance of being infected by the omikron virus after six months than those who have remained unvaccinated. Those who were boosted are 60 to 70 percent protected against omikron in the following months. In any case, the protection against hospitalization remains high.
Where did BA.2 actually originate?
BA.2 is very different from BA.1. ‘Just as much as the Wuhan virus version differs from the alpha, beta, gamma and delta variant’, says Snijder. As far as he is concerned, BA.2 could also have been given a Greek letter.
That difference indicates that BA.1 and BA.2 branched off from each other quite some time ago. It is conceivable that this is a virus that got into immunosuppressed patients or started circulating in rodents sometime early in the pandemic, and developed there – where there was a branch somewhere from BA.2.
‘That is puzzling, and somehow also worrying’, says Snijder. ‘Can sigma and tau also arise in this way?’ He looks ahead to the letters of the Greek alphabet to come. ‘We are now lucky that a less pathogenic variant has emerged. But you’re not sure if the reverse won’t happen.’
In addition, the omikron variant may provide scope for new versions of the delta variant, Snijder thinks. By the time our immune system has become more accustomed to the omikron variant, it may also have ‘forgotten’ what the spines of the delta variant look like – after which a new descendant of the delta branch could infect us again. ‘I think that cat-and-mouse game will continue for a while,’ expects Snijder.