Delta variant, Pfizer is developing the third dose of the vaccine. But the American FDA takes time

Pfizer e Biontech are developing an updated version of the coronavirus vaccine, just like Moderna (which announced it months ago), specifically designed to attack the Delta variant, the most contagious strain that is becoming dominant across the planet. Clinical trials are expected to begin in August and would be the product indicated to carry out the probable third dose of vaccine in 2022. A further recall to strengthen protection by supporting the level of antibodies.

The third dose, in fact, would be essential to preserve a high antibody titer against all variants known at the moment, including Delta. The pharmaceutical company intends to ask for theemergency use authorization as soon as reliable data on clinical trials become available, which will obviously be much faster than those of a vaccine developed from scratch, both at the EMA and the FDA. Although the US agency just has took time: US regulators have stated that fully vaccinated Americans do not need a booster vaccine. At least for now. “We are prepared for booster doses if and when science proves they are neededThe Food and Drug Administration (Fda) and the Centers for Disease Control and Prevention (CDC) explained in a joint statement.

Apparently, the early stages of administering a third dose would have shown initial data “encouraging“. The third injection would raise the level of antibodies from 5 to 10 come back against the original strain and the Beta variant (formerly known as South African) compared to the first two doses. However, the data should be published as soon as possible in a peer-reviewed journal. The point is that six months after vaccination the effectiveness of the vaccine, always high against the disease in the most serious forms, would seem to decline. And indeed, second Mikael Dolsten, scientific director of Pfizer, the data released by Israel would be affected at least in part by this effect, with an increase in infections in people vaccinated between January and February: «Probably – explained Dolsten – there is a risk of reinfection because the antibodies, as expected, decrease». In short, it will take the third dose every 12 months, even if the FDA slows down.

As we have explained several times, the neutralizing antibodies they are just a piece of the tools available to the body to defend itself. And they are obviously destined to decline if they do not encounter infection in the first few months following vaccination or recovery. The other part is made up of memory T lymphocytes, which stimulate the production of antibodies in the event of an encounter with the pathogen. By autumn we should also be able to measure the response of T lymphocytes with simpler tests: it could be a useful parameter to understand who really needs a third dose and who can do without it, perhaps reserving references to the elderly and the fragile population. «When the foreign element in the organism is eliminated – explains the Italian Pharmacological Society – the T lymphocytes they return to a state of rest, but they do not die. In fact, they are transformed into memory T lymphocytes and are placed in the lymph nodes from where they are ready to react promptly (hours / a few days) against the same epitope (for example bacterium if it returns to infect the organism). The reaction in some cases prevents the subject from getting sick, in other cases it decreases the severity of the disease and, therefore, the appearance of serious complications “.

In addition to the immunological ones, there are also elements so to speak practical to be taken into consideration, linked for example to the duration of the green pass. Green certification it is valid for 9 months from the second dose: what to do with the first vaccinated, for example all or almost all health personnel, who will see it expire in September?