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The Russian vaccine for Covid-19 had no adverse effects and induced an immune response, according to a study with preliminary results published this Friday in the scientific journal “The Lancet”, one of the most important in the world (4). Russian scientists recognized the need for further tests to demonstrate the efficacy of the vaccine.
Called “Sputnik V,” the immunization was recorded last month in Russia, but the lack of published studies on the tests has generated mistrust among the international community.
In Brazil, Paraná partnered to develop the Russian vaccine. This Friday (4), the state government reported that the results of the Russian tests had already been shared with the Technological Institute of Paraná (Tecpar) at the end of August, and that the immunization registration request must be made for 10 days to the National Health Surveillance Agency (Anvisa).
According to published results, referring to phases 1 and 2, there were no adverse effects until 42 days after the immunization of the participants, and all developed antibodies against the new coronavirus (Sars-CoV-2) within 21 days.
The Russian vaccine was tested in 76 people. All received a vaccine form (see details of test steps below), without a control group.
Furthermore, the results also suggest that the vaccine produces a T-cell response, a type of defense cell in the body, within 28 days. T cells have, among other functions, destroy cells infected by a virus.
The president of the Brazilian Society of Immunizations said that the result is important, but points out that phase 3 is still missing, in which the vaccine is tested in a large number of people.
“It is a pimponete study, expected, published in a serious journal. Today the vaccine can be categorized as a really candidate, but that still depends on a phase three study where there are 7 other vaccines.”
Phases 1 and 2 of vaccine trials seek to verify their effectiveness and safety, even with fewer participants than phase 3. Typically, phase 1 trials have dozens of volunteers, phase 2, hundreds and phase 3, Thousands.
In phase 3, the objective of the tests is to verify the effectiveness on a large scale. The steps are usually performed separately, but in the case of the pandemic, due to the urgency of the results, several vaccines have been tested simultaneously in more than one phase.
The Russian vaccine uses two adenovirus vectors, which act as a “launch vehicle” for the new coronavirus in the body: one is recombinant human adenovirus type 26 (rAd26-S) and the other is recombinant human adenovirus type 5 (rAd5 – S), which have been modified to express the new coronavirus protein S. Protein S is what the virus uses to enter and infect cells.
The adenoviruses used have been weakened so that they cannot replicate in human cells and cannot cause disease (adenovirus usually causes the common cold).
Two “versions” of the vaccine were tested: one frozen, destined for global production chains, and another lyophilized (dehydrated), destined for places that are difficult to access.
There was no control group (the one that receives an inactive substance, the placebo, so that scientists can compare the effects in those who received the vaccine with those who did not). This was pointed out by the authors as a limitation of The study.
Another limiting point, the scientists say, is that the volunteers included were relatively young, in their 20s and 30s. (Older people are at higher risk of dying from infection with Sars-CoV-2.)
