Despite the different technologies used to obtain vaccines against COVID-19, all four are approved by the two most important independent bodies (United States and Europe) have shown high efficacy, well above the 50% required by the WHO as a limit for approval.
Everything has gone so fast that three questions arise that a new document tries to respond based on the publications and press releases of the producing companies, as well as the reports of the two regulatory agencies: the Food and Drug Administration of the United States (FDA), in the USA, and the European Medicines Agency (EMA) in Europe.
For its part, the EMA has authorized the vaccines Pfizer / Biontech, Moderna and AstraZeneca/ Oxford. All have passed clinical trials involving tens of thousands of people and some are being administered en masse to the population.
To obtain approval from regulatory agencies, lVaccine-producing companies must conduct clinical trials involving tens of thousands of people. The four companies have carried out these trials in different countries, with different age ranges and at different times during the pandemic. Does it matter? Yes. Especially since in recent months variants of the virus have appeared that can be transmitted more easily and even partially evade the immune response.
In any case, after phase III trials are completed, each vaccine has been assigned a percentage of efficacy, an approximation of how well it has protected the volunteers who had received the vaccine compared to those who received a placebo. The efficacy of the two vaccines whose clinical trials were conducted later (AstraZeneca / Oxford and J & J / Janssen), in the presence of new virus variants, is lower. That is why it is difficult to compare the effectiveness of the four vaccines.
Another important difference has to do with the age range. The clinical trials of the AstraZeneca / Oxford vaccine included so few people over the age of 65 that its efficacy in this segment of the population cannot be judged. That is why in many countries it is only given to younger people.
The most serious side effects
Relevant aspects that give an idea of other benefits of vaccines should also be analyzed in clinical trials. In general, vaccines should reduce the number of people who become infected, the number of cases of serious illness, the degree of severity and hospitalization and the number of deaths. A summary of the data extracted from the clinical trials is shown in the following table.
The decrease in cases of serious disease after the application of the vaccine is very important. Also that of ICU admissions and deaths, although, as indicated in a recent Article, there are very few cases both in the placebo group and in the vaccinated group.
In the four vaccines, the adverse reactions reported in clinical trials are very similar and do not differ essentially from those observed for vaccines that are administered from birth. Some differences are observed according to the intensity, which can be mild or moderate, but they always remit after two days with usual prescription analgesics. Reactions of severe intensity have not been observed in any vaccine.
Allergic reactions have been observed which, being extremely infrequent, are classified as “of unknown frequency”. These, fortunately, have remitted after quick interventions. For this reason, rest and vigilance for 15–30 minutes after administration is recommended.
But the study of the adverse effects of vaccines does not end once they are approved. Surveillance is intended to detect any effect on the vaccination process. The third AEMPS pharmacovigilance report has already been published, in which no undescribed adverse effects have been reported for the approved vaccines, when millions of doses have already been administered.
Once the vaccines have been approved by the Regulatory Agencies, street-level studies begin in order to know the effectiveness of the vaccine. It is no longer compared between vaccine and placebo, but between vaccinated and unvaccinated people.
Although it is still too early to know these results, there is already very encouraging data. Much of this data comes from Israel, a country that reached an agreement with Pfizer / Biontech to have access to its vaccine in exchange for information on the incidence of the disease during vaccination campaigns.. Well, in Israel, hospitalizations and deaths among the population over 65 years of age have already stopped abruptly. Therefore, it seems that the effectiveness of the vaccine will be very similar to its effectiveness, that is, above 90%. And the same can be expected of the other three vaccines.
By way of comparison, the flu vaccine, which is administered massively every year, has an effectiveness of between 40 and 60%.
These four vaccines are already known to work and are safe. It is hoped that many others will reach the goal that will mean improvements, such as eliminating the transmission of the virus or adapting quickly to new variants.
What seems indisputable is that now, as a society, there is the challenge of vaccinating the population as soon as possible with these four vaccines and those that are approved. It is essential to stop the pandemic.
It is not easy to compare the effectiveness of these vaccines but it is known that it is far superior to that of others that are administered routinely, such as the flu. And yes you can compare the side effects. These are similar, and in the vast majority of cases (if they arise) they dissipate in 24-48 hours, attenuated with painkillers. Just like the vaccines that are routinely given to babies.