Human immunity resists new variants of the coronavirus

The decisive battle between humanity and the new coronavirus has begun with the mass vaccination of the population.

Humans have a ruthless weapon - their immune system spurred on by vaccines that are up to 95% effective.

The virus uses the weapons that nature itself gives it: its ability to mutate in a totally random way, a phenomenon that can give rise to new versions of itself that have advantages to escape the vaccine.

In recent days, several preliminary studies have shown that vaccines may not work as well with two of the new variants detected: the one from South Africa and the one from Brazil.

A work carried out in the African country has shown that antibodies - immune system proteins capable of blocking the entry of SARS-CoV-2 into cells - of people who have already passed the infection have between six and 200 times less potency against new variant detected.

Another work led by the microbiologist David Ho, from Columbia University, in the US, shows that the antibodies of people who have received RNA vaccines are between six and eight times less effective against this same variant.

The version of the virus detected in Brazil shares with the South African one two mutations that are probably responsible for these effects.

There are just two changes from one letter to another in the coronavirus genome, which has a total of 30,000 letters.

But those changes are right in the S protein that the virus uses to anchor itself to human cells, enter them and use their biological machinery to reproduce.

These changes mean that the antibodies do not couple perfectly to the virus and that may mean that they lose some of their ability to prevent it from entering cells.

“In the end, SARS-CoV-2 will have evolved so much that current vaccines will no longer be effective

The Moderna company confirmed that according to its own studies, people who have received its vaccine generate antibodies that are about six times less effective in neutralizing the new variant of the virus.

The good news is that the vaccine is still effective, and likely to prevent coronavirus from causing disease.

The company has announced that it is already developing a new version of its vaccine specifically designed to neutralize the new variants.

BioNTech / Pfizer has noted that it can develop new variants of its own vaccine in less than two months.

Both companies have shown that the UK variant, the third worrisome because it is more contagious, responds just as well to vaccines.

“In the end, SARS-CoV-2 will have evolved so much that current vaccines will no longer be effective,” explains Paul Beniasz, a virologist at Rockefeller University and co-author of one of the studies on the new variants.

“But this process,” he warns, “will probably take years.

“As people become immunized with the vaccine or with the infection, there will be fewer serious cases in hospitals.

This does not mean that the virus changes.

It is highly unlikely that it will evolve to become more or less virulent.

In the end we will end up in a situation in which everyone will be infected as a child and will be infected again later, but with very mild or non-existent symptoms, "he explains.

The important thing is that the population that can die from covid will already be vaccinated.

It is important to understand that this will probably save them from coronavirus, but it may not prevent the virus from entering their bodies and being able to transmit it.

Hence the assumption that SARS-CoV-2 will never disappear, but will instead become an endemic virus.

Another recent work based on a mathematical model estimates that with current vaccines it will be impossible or unfeasible to achieve group immunity.

The relatively imperfect protection provided by vaccines - 70% to 95% effective - and the arrival of new variants will keep the virus in circulation unless 89% of the population is vaccinated.

With the new variant of the United Kingdom that percentage reaches an impossible 130% of the population, according to Paul Hunter, virologist at the University of East Anglia (United Kingdom) and co-author of the work.

"Our conclusion is that it is not necessary to achieve group immunity," he explains.

"As long as we can prevent people from dying from covid it is enough, and to guarantee that, current vaccines are enough," he adds.

"If you ask me if I prefer to have a lot of antibodies or a lot of T lymphocytes, I would definitely say the latter"

"In the case of the South African variant, and probably also the Brazilian one because it shares the same mutation, all the data obtained on antibodies does show a consensus on a partial decrease in neutralizing capacity of around 25%", explains Carmen Cámara, from the Spanish Society of Immunology.

"In other words, our level of protection will drop from 95% to around 70%, a percentage that is still very high," he adds.

One of the biggest shortcomings of all the studies on the new variants is that they only tell a minority part of the story.

These works are based on measuring the potency of neutralizing antibodies and they do it in the laboratory, not studying what happens in the organism of infected or vaccinated people.

There is a world of difference.

Humans would be lost if we only trust our survival to the virus on antibodies.

The immune system consists of many different types of highly specialized cells.

Among all of them stand out different types of T lymphocytes, white blood cells that receive a very detailed robot portrait of different parts of the virus and that together function as an elite army that is almost impossible for the virus to fool with one or more mutations.

“If you ask me if I prefer to have a lot of antibodies or a lot of T lymphocytes, I would definitely say the latter,” explains Antonio Bertoletti, from Duke University.

"They may not prevent infection, but they will stop the spread of the virus so that you will only have a cold," he says.

This immunologist has published a study that shows that after an infection - and probably also after vaccination - a person generates dozens of different lymphocytes.

Each one attacks a very specific part of the virus, preventing it from escaping.

“We have started studying lymphocytes in people who have received RNA vaccines.

The good news is that 10 days after the puncture there is already a good response in this regard.

We are now studying whether some mutations could affect T lymphocytes, but most epitopes [virus fragments] that these lymphocytes recognize are outside the receptor-binding domain [the S protein], so they will not be affected by mutations in T cells. new variants.

It is possible that we will find one or two people with worrisome mutations, but it is very doubtful that this is the norm ”, highlights Bertoletti.

In Spain, immunologists from several hospitals in Madrid, Barcelona and Cantabria are doing the same studies and have seen something very similar.

“Ten days later we already see a very strong lymphocyte response and this is before antibodies have developed.

This response is probably protective against the virus ”, explains Jordi Ochando, researcher at the Carlos III Health Institute in Madrid and coordinator of the study.

Applying what is known about the immune system and what has already been seen with this virus, the logical thing is to think that the new variants will not be able to escape the immunity mediated by lymphocytes.

There is a specific type of these cells that have memory and are able to remember a virus months and even years later.

“There are studies that have already shown that people who do not develop antibodies nevertheless have immunity to the coronavirus.

The answer is obviously in the lymphocytes ”, explains Manel Juan, immunologist at the Hospital Clínic de Barcelona.

Jordi Ochando's team is applying in Spain the lymphocyte test developed by Antonio Bertoletti's team in the US It is a test that requires a bit more logistics than PCR or antigens.

A blood sample is taken, fragments of the virus are added, and it is waited to see if the memory lymphocytes react.

It takes about 24 hours to get the results.

Ochando's team has already analyzed 250 people.

Its objective is to carry out a large study of vaccinated people, infected from the first and second waves, immunosuppressed people and healthy controls to know the real strength and duration of immunity against the coronavirus mediated by lymphocytes.

According to the most recent data, it lasts at least eight months.

A recent study published by the La Jolla Center for Infectious Diseases (USA), a world reference in immunity, has just shown that the cellular response is effective even against new variants of the virus.

The number of different lymphocytes is so high that the mutations affect only 8% of them, so that there are still 92% to be able to locate and destroy the infected cells.