How is the ‘silent’ omicron, the dominant sub-variant around the world – Health

The extremely transmissible omicron variant is being replaced worldwide by a sub-variant, the BA.2, also known as “stealth omicron”.

Until mid-March, the most common variant on the planet was the BA.1, which surprised experts due to its level of transmissibility, although it was less dangerous than others.

But already the WHO (World Health Organization) said that the subvariant BA.2. it represents almost 86% of the sequenced cases.

Infections, which were rapidly declining everywhere after unimaginable daily highs caused by omicron, have risen again in Europe in recent weeks, and according to the director of the WHO European division, Hans Kluge, it is due to the BA lineage. two.

This Tuesday, the Centers for Disease Control and Prevention (CDC, for its acronym in English) of The United States reported that around 55% of new covid cases in the country were due to BA.2. That means that it is already the dominant variant in the country.

Given this, the Food and Drug Administration (FDA) also authorized this Tuesday a second booster dose of the anticovid vaccine for people 50 years of age or older four months after receiving the first booster.

In Asia there has also been a spike in daily detected cases since mid-February.

“Silent” subvariant

BA.2 is often referred to as a “silent” subvariant, because it lacks the genetic marker that researchers had been using to quickly determine whether an infection was most likely to be with the “regular” omicron (BA.1). , instead of the delta variant.

As with other variants, a BA.2 infection can be detected by lateral flow testing or PCR. but these tests cannot distinguish BA.2 from delta. Other tests are needed to be sure.

BA.2 is more transmissible than normal omicron but, fortunately, it is not more serious.

But how worried should we be about this variant?

Next, we tell you what is known about it.

What is the BA.2?

As viruses mutate into new variants, they sometimes divide or branch into sublineages. The delta variant, for example, consists of 200 different sub-variants.

The same happened with omicron, which includes lineages BA.1, BA.2, BA.3 and B.1.1.529.

It is unclear where it originated, but it was first detected in November among sequences uploaded to the database from the Philippines.

It has been designated as a “variant under investigation” by the British health authorities, which means they keep a close eye on it but don’t worry too much about it.

Although vaccines are less effective against it and protection decreases over time, a booster dose increases protection and prevents hospitalizations and deaths, according to data from the UK Health Security Agency.

Is BA.2 more contagious?

A study of 8,500 households and 18,000 people by Denmark’s ISS, which has not yet been peer-reviewed, found the BA.2 subvariant to be “substantially” more transmissible than BA.1.

BA.2 was more efficient at infecting vaccinated people and with a third booster dose than previous variants, according to the study, although vaccinated people were less likely to transmit the virus.

While a study in the UK also found that BA.2 was more contagious compared to BA.1.

Is the BA.2 subvariant more dangerous?

There are no data to suggest that BA.2 causes more severe disease than previous omicron subvariants.

Experts assure that this subvariant is now infecting more due to the relaxation of containment measures in many countries.

As with previous variants, experts say the vaccines will still be highly effective in preventing serious illness, hospitalizations and death.

However, this subvariant is a reminder that the virus continues to harm unvaccinated people, those who have not received booster doses, or the most vulnerable.

“(The coronavirus) It is still a big public health problem and it will continue to be,” said Mark Woolhouse, an epidemiologist at the University of Edinburgh (Scotland), according to the Reuters agency.

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BBC-NEWS-SRC:, IMPORTING DATE: 2022-03-30 00:50:25

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