Delta, mu and other variants of coronavirus: who needs a third vaccination | World Events – Estimates and Forecasts from Germany and Europe | DW

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The number of new cases of coronavirus infection in many countries is growing rapidly again. In addition to the now widespread delta variant, other fearsome variants, such as lambda or the more recently discovered C.1.2 and mu, are rapidly spreading. In this regard, the question arises: maybe it’s time to strengthen the immune defense with a third dose of the vaccine?

Coronavirus infections after full vaccination do not happen very often, but, nevertheless, their number is increasing: in Germany alone, according to the Robert Koch Institute, by mid-August, for 48 million people who received two vaccinations, there were 13,360 cases of infection with obvious symptoms.

The Israeli and US authorities have already decided that all residents of the country must undergo revaccination and be vaccinated with the so-called “booster”. Only in this case will a person be considered fully vaccinated.

In Israel, the third vaccination against coronavirus is given to all residents of the country

In other economically developed countries, on the contrary, it is believed that the third vaccination is needed only for those who are at risk: the elderly or patients with chronic diseases and weakened immunity, for example, those who take suppressive drugs.

Germany will revaccinate – but not all

In Germany, they want to vaccinate for the third time only those who are at increased risk of contracting coronavirus. The German Standing Commission for Vaccinations (Stiko) has not yet released general guidelines for revaccination. But in many federal states, they are already offering a third vaccination to those residents of nursing homes who have undergone a full vaccination – 2 vaccinations – at least six months ago. In addition, people with reduced immunity and older people who need outside care can also be vaccinated for the third time.

Those who have been vaccinated with vector drugs – AstraZeneca or Johnson & Johnson – can also receive the third vaccination with BioNTech / Pfizer or Moderna mRNA vaccines from the beginning of September. Studies have shown that after the so-called “cross-vaccination”, a much stronger immune response is generated than after two AstraZeneca vaccinations.

What is the meaning of the third vaccination?

Usually, the so-called “booster” effect occurs after the second vaccination: upon repeated contact with the same pathogen – be it a re-vaccination or an infection – an enhanced and accelerated response of the immune system occurs.

Elderly man in California being vaccinated against coronavirus

People with weak immune systems are at risk

This reaction is triggered by the so-called memory cells, which appear in the body after the first vaccination. They recognize the antigen and react quickly to neutralize and destroy the pathogen. This is why the second shot is so important. However, in people with weakened immune systems, the immune response is sometimes not as strong. Revaccination helps to enhance it.

Vaccine manufacturers: the protective effect is declining

In mid-July, mRNA vaccine manufacturers BioNTech / Pfizer concluded that the protective effect of the drugs they created began to decline six months after the second vaccination. And then a third dose will be needed – especially for people with weakened immune systems.

Booster vaccination provides “the highest level of protection against all coronavirus variants tested to date, including the delta variant,” the drug manufacturers said in a statement.

WHO urges rich countries to drop third vaccine

But if in industrialized countries the level of vaccination is quite high, then in many poorer countries of Asia, Africa and Latin America, due to a lack of drugs, only a small part of the population can be vaccinated.

Therefore, WHO calls for abandoning revaccination against coronavirus until at least ten percent of the population in every country in the world is vaccinated against it. Rich countries should refrain from the third vaccination at least until the end of September, said WHO Director-General Tedros Adhanom Ghebreyesus – on their part it would be an act of solidarity with poorer countries.

Since the start of the pandemic, this statement by the head of WHO has become the organization’s strongest appeal. However, it has nothing more than a recommendatory nature, and the countries that make up WHO are not obliged to follow it.

Infographic - SARS CoV-2 coronavirus variants

However, uniform vaccination is not only a matter of fairness. Due to the lack of vaccines in poorer countries, more and more variants of the virus may arise, and then in the medium term it will become a problem for rich countries.

According to the WHO, the longer the coronavirus circulates among the unvaccinated population, the higher the likelihood of the appearance of new mutations: such as the lambda variant C.37, which is now widespread in Latin America, the mu variant identified in Colombia (B1.621), or the variant C.1.2, first discovered in May in southern Africa.

Delta, mu, C.1.2 – who’s next?

Another variant of the coronavirus, identified in January with the Greek letter µ – mu, was recently classified by WHO as a “variant under surveillance” because it has mutations with potential resistance to coronavirus vaccines.

And option C.1.2, running in South Africa, the Democratic Republic of the Congo, Mauritius, Great Britain, China, New Zealand, Portugal and Switzerland, is genetically the most distant from the original SARS-CoV-2. Compared to other variants, it has an unusually high number of mutations – up to 41.8 per year, which allows it to mutate at maximum speed, American epidemiologist Eric Feigl-Ding wrote on Twitter.

This rapid evolution amplifies the possibility of so-called “escape mutations” that can bypass the vaccines that still exist today, based on the original type of coronavirus.

It is for this reason that it is imperative that vaccination rates rise significantly, not only in wealthy countries, but around the world, explains Professor Penny Moore of the National Institute of Infectious Diseases in South Africa in an interview with DW Africalink radio program: “New options are currently low vaccination rates. They only appear when a person is infected. Increasing vaccination coverage worldwide will lead to fewer infections. This, in turn, is the only way to reduce the number of new options.”

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