A year and a half of a pandemic without understanding of immunity against covid Science

A year and a half of a pandemic without understanding of immunity against covid  Science

A Palestinian receives a coronavirus vaccine vaccine at the Khan Younis refugee camp in the southern Gaza Strip.MOHAMMED SABER / EFE

Deposit delta variant and its hypothetical ability to outsmart the immune system has become the perfect alibi for manufacturers RNA vaccineswho have been pushing for approval of the third booster dose for several days.

It’s possible, that is mixed from almost start a pandemic and that would mean huge additional revenue for companies like Pfizer, the main champion of the third injection. The problem is that their arguments are based on confusing, secret and premature data, as the major US medical authorities have pointed out, which have rejected the third dose until more data is available. The World Health Organization has also questioned the need for this new dose and criticized that it was now being discussedIn much of the developing world, there are millions of people who have not even received the first injection.

Carmen Cámara, an immunologist at La Paz Hospital in Madrid and a member of the Spanish Immunological Society (SEI), confirms that “Pfizer was the first in the vaccine race and achieved an advantageous position that it now does not want to lose. It is a 100% commercial movement. “That doesn’t mean you have to take the third dose in the end, but there’s no data available now and there’s no time to decide,” the expert said. “It is now important to complete all second doses in developed countries and expand vaccination to the rest of the world with the most suitable vaccines for their situation, which will be from Janssen, Astra Zeneca, Novavax or others more suitable for their protection needs. … cold and its price. That’s a priority and it’s not what gives Pfizer money, “he adds.

The main scientific argument of Pfizer and BioNTech is that they have seen a decrease in antibodies to coronavirus between 6 and 12 months after full vaccination. The third dose would multiply between 5 and 10 times the level of these proteins in the blood capable of neutralizing the virus.

The problem with deciding immunity based on the amount of antibodies is that it is not yet known what levels are necessary to prevent infection and disease.

The data come from a clinical study organized by the company. These are partial results that have not yet been reviewed by independent experts or published in a scientific journal. The company also cites real experiences from Israel, a country very advanced in vaccination, thanks to its agreements with the company, which have ensured that the effectiveness of the vaccine decreases after six months and allows reinfection with the delta variant. The country has made a controversial decision to start giving the third dose to particularly vulnerable people, such as those with an organ transplant. However, the country data also show that the protection against hospitalization and serious illness with the delta two-dose vaccine variant is practically the same as for the other variants.

César Hernández, head of the Spanish Medicines Agency’s Human Medicines Division, admits: “We are all waiting to see how convincing the data on possible vaccine failures will be.” Health authorities have to find a difficult balance. “If we wait until we get a lot of real data on cases where vaccines fail, more people will be exposed to the infection, and if we decide too soon on the basis of an indirect variable such as antibody levels, we may end up giving another dose to people who don’t need it.” explains.

Remember that the problem with deciding on immunity is based on the number of antibodies or even the number of lymphocytes Antonio Bertoletti, from Duke University (USA) is that it is not yet known what levels are necessary to prevent infection and disease. This immunologist published one of the studies, which shows that after infection – and probably also after vaccination – a person generates dozens of different lymphocytes. Each of them attacks a very specific part of the virus, which prevents it from escaping from any variant.

Another argument in favor of the third dose is based on a study published a few days ago that illustrates the problem the world has faced from the beginning pandemic. The work showed antibodies from people who only received one dose of vaccine completely neutralizes the delta variantwhile for two doses yes. These data come from laboratory experiments – and not from actual cases – where the virus is grown in a vessel and blood from vaccinated or cured COVID is added to measure neutralizing capacity.

Since the onset of the pandemic, the vast majority of immunity studies have focused on antibodies, a huge limitation because they neglect the activity of immune system cells, especially the lymphocytes that make up kind of elite army. Months, even years after the antibodies have disappeared from the blood, memory lymphocytes can reactivate when the virus reappears and organize new defenses, including the production of new antibodies. The most interesting thing is that so far these immune cells have proven to be invulnerable to mutations that the virus accumulates in different variants. Several studies have shown antibodies to vaccinated people or those who have undergone covid neutralize all known variants. So far, there are no data on the delta, but logic suggests that it can do it, experts say.

The President of the CEI, Marcos López-Hoyos, adds that in Spain there are currently no consolidated data on how many are being reinfected and what variant, even if these are “exceptional” cases. He explains that at Marqués de Valdecilla de Santader Hospital, where he is the head of immunology, a full vaccination schedule had only 2% of all infections. “People who have been fully vaccinated are protected,” he says.

One year and a half after the onset of the pandemic, it is still unknown how long the innate or vaccine immunity lasts

Immunologist Jordi Cano Ochando studies the cellular immunity level of the general vaccinated population as well as immunosuppressed people in Spain, where he works at the Carlos III Medical Institute, and in the United States, where he is affiliated with Monte Sinai Hospital. in New York. “For now, we see a good immune response to the new variants,” he says.

Most of the experts consulted think that data on the administration of the third dose to the general population are still not available and that this will probably never be necessary, with one exception: some immunocompromised patients, such as those who have just received a transplant. The challenge now will be to measure their antibody and lymphocyte levels, which is not always easy.

A year and a half after the start of the pandemic it is not yet known how long innate or vaccine immunity lasts. It’s completely logical. The best way to find out is to let time pass. “For now, we know that cellular immunity lasts a little over a year,” Carmen Cámara points out. This protection can be much longer. Bartoletti emphasizes that “in the case of SARS [otro coronavirus que emergió en 2002 y mató a unas 800 personas] memory immune cells were still active 17 years later. ” “These memory lymphocytes have very low levels in the blood, but some of them are divided into bone marrow or lymph nodes and are always ready to return to action if needed,” he says.

At the moment, Spain is facing the challenge of human resources, says Cámara. “In general, there are fewer immunologists studying cell protection in hospitals than there are microbiologists studying humoral protection.” [anticuerpos] and this partly explains why we do not yet have enough data to create protective correlates [saber qué niveles de linfocitos protegen de la infección y la enfermedad]”Explain.” Commercial cell testing costs about 50 euros per patient, so it can’t be extended to everyone, but in selected cases it’s perfectly acceptable. “The bottleneck is that it must be the immunologist who selects the cases and interprets them. “He adds and allows himself to be solved by creating a National Center for Immunology, just as it already exists for microbiology.” Perhaps they would pay more attention to us, “adds Cámara.

Manel Juan, Head of Immunology at Clínico de Barcelona Hospital, has a fatalistic approach to the third dose. “It’s not justified now, and it won’t be in the future if the cost-benefit relationship is taken into account,” he says. “But it will inevitably be approved because of concerns about this wave, in which infections are still rising, even if they do not have a major impact on hospitalizations or deaths, and also because it will not hurt to receive it.” It happens that many people do not take the third dose, and then we know the real effect. So when pharmaceutical companies try to sell the fourth dose, they may not succeed. Deep down, who cares about studying cellular immunity? To those who have no financial interests, “he adds.

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