Filenews 22 November 2020
Vaccinating as many people as possible against the coronavirus is vital in order to put a "brake" on the Covid-19 pandemic. However, in order to do this, many scientists consider it necessary to make vaccines as transparent as possible in advance, so as not to create ex post "noise" that will enhance anti-vaccination views.
In this respect, one of the things that needs more clarification is what exactly it means that in their clinical trials Pfizer/BioNTech and Moderna vaccines have shown - more than expected - efficacy of around 95% (while the Russian "Sputnik-5" over 90%) and whether this means that almost everyone who makes these vaccines will be "invulnerable" to the crown.
"These are vaccines that change the terms of the game. We all expected efficacy of 50% to 70%," vaccine researcher Dr. Gregory Pauland of the American Mayo Clinic told the New York Times ..
However, as the scientific editor of the NSTs, biologist and author Carl Zimmer, explains, the 95% effectiveness in the trials does not mean that they will be the same in practice after mass vaccinations. Efficacy in tests is a statistical indicator derived from specific mathematical calculations.
The pharmaceutical company vaccinates some people, while in others it gives a virtual vaccine (placebo), without any participant knowing whether or not it has actually been vaccinated ("blind" test). Then the vaccinated and pseudo-vaccinated normally make their lives and the company monitors how many will experience covid-19 symptoms and be diagnosed positive for coronavirus (170 people in the case of Pfizer/BioNTech). Then it is calculated which percentage of the patients had been vaccinated and which were not, as well as the relative difference between the two percentages. In the case of both vaccines, the vast majority of those who became ill had not been vaccinated. This difference, expressed as a percentage (e.g. 95%), shows efficacy and is a convincing indication that the vaccine is "working" well.
However, as experience with previous vaccines has shown, the effectiveness of trials is different from the effectiveness of a vaccine in the real world and it is important, according to experts, that these two types of efficacy are not confused. 95% does not represent the real probability of someone being infected with the coronavirus, nor does it amount in practice - as many wrongly think - to the fact that 95 out of 100 people who will be vaccinated will certainly not become infected or sick.
"Effectiveness shows how well the vaccine works out in the real world," according to Associate Professor of Epidemiology Jor Bar-Zeev of the School of Public Health at Johns Hopkins University in Baltimore.
Perhaps the efficacy of anti-coronavirus vaccines in tests (efficacy) proves equally impressive in practice (effectiveness), but based on previous vaccination experience, it will probably be somewhat less- unknown how much. This is partly because the few thousand people participating in the clinical trials are not a representative sample of the population. For example, "out there" are people with a variety of chronic health problems that can affect the effectiveness of the vaccine.
Unknown asymptomatics vaccinated
On the other hand, tests on Pfizer/BioNTech and Moderna vaccines, as in others, were designed to show whether they protect people from getting sick with covid-19. If a volunteer in the test had a fever or a cough, he took a test. But the tests didn't catch those infected with the coronavirus, but without symptoms. It is therefore possible that some people who were vaccinated in the trials were infected but without their understanding neither themselves nor the pharmaceuticals (who have no way of knowing, since they did not have a post-vaccination coronavirus test on all those who participated in the trials, but only on those who showed symptoms along the way).
If such cases of vaccinated asymptomatic bodies of the coronavirus exist, they can continue to transmit the virus, as asymptomatics are known to be contagious, even though - according to some estimates - they have a lower viral load. In fact, if someone has had the vaccine and recklessly thinks that it is no longer possible to get sick or even become infected with the coronavirus, then they will relax the prevention measures, e.g. by no longer wearing a mask or by keeping their distance from others.
"In this case, there could be the paradoxical situation, things could get worse" rather than vaccination, warns Dr Bar-Zeev.
Another critical factor that will determine the actual efficacy of the vaccine will be what percentage of the population will do it. Scientists know that even a vaccine with amazing efficacy in testing can make little substantial difference in the world if only a few people are vaccinated.
"Vaccines don't save lives. Vaccination programs save," says Professor David Paltiel of Yale University's School of Public Health. He led a recent modelling study published in the journal Health Affairs and concluded that, in terms of reducing cases, hospital admissions and covid-19 deaths, the extent of the vaccination program has the same impact as the vaccine's effectiveness in testing.
Source: RES-BE
