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The subvariant of omicron,

BA.2,

informally called

omicron 2

, is constantly on the rise around the world.

Its presence has already been confirmed in 43 countries and, according to the latest monitoring by the

World Health Organization

, it represents 21% of

omicron

cases .

Ten countries already have

omicron 2

as the predominant variant, including

China

, the

Philippines

,

India

,

Nepal

and

Denmark

, where it reaches 66%.

In southern Europe at the moment it represents only 3% of cases.

Is it more or less transmissible than omicron?

Early studies indicate that

BA.2

is more transmissible than

BA.1

.

Estimates in

Denmark

and

the United Kingdom

indicate that

omicron 2

is between 30% and 50% more transmissible than

omicron

.

In a Danish study with 8,000 families, unvaccinated cases infected with

BA.2

were found to be more likely to transmit the virus to family members than those infected with

omicron

.

However, even those who had completed the vaccination course were more vulnerable to the BA.2 variant than to BA.1.

Omicron 2

grows both in countries where there is a decrease in the pandemic wave and in those where there is growth, and this data supports the hypothesis that the reason for the increase in diffusivity is due more to greater transmissibility than to immune evasion of vaccination or previous infection.

A laboratory study confirms this hypothesis.

Is the disease more serious?

There is currently limited evidence on possible differences in disease severity induced by

omicron

and

omicron 2

variants .

In

the UK

, where

omicron 2

has grown steadily in recent weeks, there has been a decline in hospitalizations and deaths.

An analysis from

Denmark

showed no difference in the risk of hospitalization between people infected with

omicron

or

omicron 2

, although there has been an increase in the number of hospitalizations and deaths in the country since the latter became dominant.

However, the variant does not appear to cause more severe disease, even in children.

In

Nepal

, where

omicron 2

prevails with very high percentages, the number of hospitalizations, even in intensive care, is decreasing.

The same is true of

South Africa

, where

omicron 2

is 86% and hospital admissions continue to decline.

A Japanese laboratory study published in preprint just three days ago concludes that it could cause more severe illness.

The researchers infected hamsters with

omicron

and

omicron 2

.

Animals infected with the second variant became more severely ill and had more impaired lung function.

According to Japanese scientists,

omicron 2

has virological and pathogenic characteristics that distinguish it from the previous strain and should therefore be considered a variant of concern in its own right.

Their analysis also determined that the reproductive rate of

omicron 2

would be 1.4 times higher than that of the previous strain, and that the new

omicron

subvariant appears to be more replicative in human nasal epithelial cells than the original.

Are vaccines effective?

Several studies suggest that

omicron 2

can easily overcome immunity induced by vaccination or previous infection with other variants, but not much different than what omicron is already doing compared to the variants that preceded it.

In fact, some analyzes carried out in

the United Kingdom

and

Denmark

even show a greater capacity of the vaccine to prevent

omicron 2

than 1.

Data from

the UK

indicate that the administration of a booster dose two weeks after the second dose of the vaccine showed an efficacy of 63% in the prevention of symptoms of the disease caused by

omicron

and 70% in the case of

omicron 2

, but the efficacy data decrease over time in both variants.

However, the results of the studies carried out so far are not unequivocal.

Work led by virologist

David Ho

of

Columbia University

in New York City confirmed that

omicron 2

and

omicron

have similar abilities to resist neutralizing antibodies in the blood of people who had been previously vaccinated or infected.

But Ho's team reported that genetic mutations unique to

omicron 2

affect how some antibodies recognize the variant.

In fact, some antibodies would be less effective in neutralizing the second, while, on the contrary, another type of antibody tends to be more active with it.

"It is unlikely that there are any higher risks with

omicron 2

than with

omicron

," he says.

Could omicron 2 lead to a new pandemic wave?

Scientists believe that omicron 2

is unlikely to

trigger a new major wave of infections, hospitalizations and deaths, following the wave of

omicron

.

However, the variant could create greater problems in countries with low vaccination rates.

" Omicron

's sister

could prolong the pandemic wave. But our data suggests there will not be a new surge,"

Dan Barouch

, an immunologist and virologist

at Beth Israel Deaconess Medical Center

in Boston, an author of a study , tells

Nature .

In his case, the neutralizing antibodies induced by three doses of the

Pfizer

vaccine proved slightly better at preventing the original variant.

"But this small difference in immunity avoidance is unlikely to explain the increase in BA2 around the world," Barouch says.

Can omicron 2 infect those who have recovered from omicron?

It is not yet clear whether the new variant is different enough to cause reinfection in people who have been infected with

omicron

.

We know that those who have recovered from

omicron

can feel quite comfortable because contagion with the same variant is considered highly unlikely as specific antibodies have developed.

But

omicron 2

is not the same virus: it shares 38 mutations with the original variant but has an additional 27 unique mutations.

Researchers in

Israel

have identified a handful of cases in which people cured of

omicron

subsequently became infected with its sister variant.

The

State Serum Institute

in

Copenhagen

has launched a study to determine how often these reinfections occur.

Troels Lillebaek

, leader of the investigation, says that he would be surprised to discover that there is no protection.

What is the time of onset of symptoms?

From a preliminary

UKSA

survey based on monitoring the situation in

the UK

, the median time to onset of symptoms would appear to be half a day shorter for

omicron 2

than for

omicron

, with a median period of 3.27 days compared to 3.72 days, respectively.

With

Delta

, the interval between infection and onset of symptoms was approximately four days.

The shorter incubation time could contribute to the increased growth rate of

omicron 2

.

Do omicron 2 treatments work?

A preliminary laboratory study found that

omicron 2

is resistant to the monoclonal antibody

sotrovimab

, the only one so far believed to be effective against

omicron

.

On February 9,

Vir Biotechnology

, which together with

Glaxo

produces the drug, declared that experiments carried out by the pharmaceutical company and not yet released, suggest that the monoclonal is also effective against the new variant.

There is no data yet on the effectiveness of the antiviral.

Do the tests detect omicron 2?

Omicron 2

has also been defined as "invisible" because it is difficult to identify, since it does not have the characteristic "S gene deletion" of

omicron

: to find it, therefore, it is necessary to sequence all the samples and this implies a capacity of laboratory that not all countries have.

The lack of the S gene, on the other hand, is what allows us to suspect that a sample belongs to the

"classic" type

omicron variant directly from the unsequencing test, which is done later.

Conforms to The Trust Project criteria

Know more

  • Omicron variant

  • Coronavirus

  • covid 19

  • HBPR

HealthThe perfect storm of infections Omicron, third doses and Covid passport: keys to understanding the peak of infections

CoronavirusWhat is known about the silent sister of ómicron?

28 unique and 32 shared mutations

CoronavirusReinfection with omicron: What chance do I have of being infected again, and how long after?

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