Scientists have missed forecasts, and this year's flu vaccine is less effective

Every year, the seasonal flu vaccine is adapted to viruses that are expected to be the most common this coming winter, but this year an unexpected strain emerges that is becoming dominant and even the vaccinated have no antibodies against it and the risk of serious illness increases.

Walla!

health

21/12/2021

Tuesday, 21 December 2021, 11:48 Updated: Wednesday, 22 December 2021, 11:59

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Every year again we are present to discover that the flu can be worse than we think, and this year too there are quite a few people who have caught it quite hard. However, there is a feeling that this year's flu season is particularly bad (as if dealing with a fifth wave of illness in the new Corona variant of the Omicron is not enough for us), and according to scientists there is a disturbing reason for this. Researchers who tested the effectiveness of the seasonal flu vaccine against the common flu strains actually practiced in 2021 found that it is unable to deal with a mutation in the specific strain that appears to be the most dominant in infecting people this year.

It is important to note that these findings are preliminary, and are currently only published on preliminary platforms aimed at enabling peer review prior to publishing the conclusions in journals and public channels.

According to the researchers, a mutation in the H3N2 strain (also known as influenza A) of the flu virus is becoming more and more common in the season season, and it seems that the vaccine adapted for the flu season 2121-2022 fails to neutralize it.

This means that even people who have been vaccinated against the flu this year may still get this common strain because the antibodies they have developed following the vaccine are not compatible with the strains circulating in the population.

More on Walla!

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To the full article

Does not cause the development of neutralizing antibodies against a mutant strain that is becoming extremely common and not included in the predictions.

Nurse prepares flu vaccine (Photo: Reuven Castro)

The name of this mutation, which scientists define as a type of branch in the H3N2 strain genus branch, is - 3C.2a1b.2a2.

"3C.2a1b.2a2 H3N2 viruses replicate efficiently in human cells, and may cause a mismatch antigenic if spinning a high amount of population during the upcoming flu season," wrote Dr. Scott Hensley, a researcher at the University of Pennsylvania, preliminary medRxiv platform which published the study.

The researchers added another Because the mutant strain in question has been found in increased quantities in recent weeks in the U.S., in cases of influenza diagnosed in November and December.

"This specific strain of influenza first appeared relatively early in the early Corona epidemic and it almost completely took over all H3N2 influenza strains in Europe, Oceania, South Asia, West Asia and North America during 2021," the researchers explained.

Why does the flu vaccine not protect against all strains?

A universal flu vaccine, one that will be effective against all existing strains of the virus, is something that scientists are continuing to work on developing vigorously even at the present time. But it is not yet available. The seasonal vaccine works in a different method - every year scientists and doctors gather and try to predict as accurately as possible the strains that will be common in the upcoming flu season and adapt the vaccine to their measurements. These are usually 3-4 strains against which the vaccine protects. The effectiveness of the seasonal vaccine is affected by a number of factors, including age, health status and also the degree of suitability of the vaccine for existing viruses.

In the clinical trial on which the present study is based, 40 healthy people who were vaccinated with the seasonal flu vaccine of the year were tested. The researchers found that more than half of them had poor protection against the flu strain with the mutation (3C.2a1b.2a2). In fact, in a tweet he posted to his Twitter account, the Hensley researcher wrote that 55 percent of those vaccinated had "undetectable levels of neutralizing antibodies against 2a2 H3N2 after vaccination."

Even in years when its performance is lower than normal it is still effective in protecting against some strains.

Influenza vaccine (Photo: Reuven Castro)

And despite the vaccine's inadequacy for common viruses this season, researchers still think people should be encouraged to get vaccinated against the flu vaccine.

They say even in years when vaccine performance is below average it is still effective in protecting against some strains and preventing unnecessary people from developing a serious illness and dying from the flu.

Influenza situation in Israel

Influenza viruses also come to Israel, and there is a recommendation for the entire population to be vaccinated against the virus every winter.

However, not the entire population is exposed to the same risks from the flu virus.

Elderly people are considered a group at high risk of developing a serious illness, complications and even dying as a result of flu.

In fact, about two-thirds of hospitalizations due to the flu are in the elderly and they also make up about 90 percent of deaths due to illness.

In recent years, the percentage of vaccinated in the elderly group in Israel has been about 60 percent.

And they receive the same seasonal vaccine at the same dose as the rest of the population.

Who is the increased vaccine recommended for? Man vaccinated against influenza, Maccabi Health Insurance Fund, December 2019 (Photo: Official website, Maccabi Health Services)

But for this population exposed to increased risk there is also an adapted flu vaccine with an increased dose accordingly.

This is a vaccine that contains 4 times the substance (maglutinin) in the regular flu vaccine given every year in Israel.

The advantage of a high dose compared to a regular dose vaccine is its higher effectiveness.

According to studies published worldwide, an increased dose vaccine reduced all influenza morbidity by 24.2 percent compared to the standard vaccine.

Despite the increased dose of the active ingredient, these vaccines are considered safe to use and have few mild side effects like redness, swelling or pain at the injection site.

In several countries around the world, there is already a recommendation for the adult population over the age of 65 to be vaccinated with the increased dose, but the Israeli Ministry of Health has not adopted such a recommendation so far and therefore the vaccine given to this age group in Israel is the same.

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