In less than twelve months, some vaccines against a Covid-19 have already been approved and are being applied in dozens of countries. Despite undergoing rigorous studies, there is still suspicion about their safety and effectiveness. After all, is it possible to develop a vaccine in such a short time?
First of all, know that there is no predetermined time for the development of immunizers. The duration of the process depends on many variables: success of pre-clinical research, still in the laboratory, recruitment of volunteers, vaccination, monitoring, evaluation by regulatory bodies and so on.
“Producing vaccines is a risky investment. We estimate that between 7 and 10% of those that start to be elaborated are approved and distributed ”, points out the epidemiologist Denise Garrett, deputy director of the Sabin Vaccine Institute, US United States.
Until then, the vaccine that occupied the fastest position was that of mumps, which took four years to appear in the 1960s, when the testing phase was simpler and shorter. The do ebola, more recent and made according to current protocols, took five years.
A combination of factors caused the newborns to break these records. First, the fact that we are experiencing the greatest pandemic in history since the Spanish flu, at the beginning of the last century. So far, more than 1.5 million people have died and there is no specific treatment against the disease.
“In such a situation, the laboratories do not walk as in a walk in the park. They run as if they were at the Olympics, wanting to get there first and fast ”, jokes Denise.
In other words, if before investments were made slowly and with caution because of the risk, the current urgency has made governments and private entities go to great lengths to pay for the work of scientists.
“In this way, it was possible to move forward quickly. Never before have so many pharmaceutical companies been involved in a vaccine. We had over seventy interested parties ”, reports the expert.
Besides, the dedication of the researchers and the financial contribution helped to remove anonymity new, faster and simpler technologies, such as viral vector vaccines (AstraZeneca, Janssen and Sputnik V) or messenger RNA (Pfizer and Moderna). They are unknown to the public, but they did not arrive yesterday.
“These new platforms have been studied for decades. What happened was that the pandemic accelerated this use, that way we got more than one safe and effective immunizer in less than a year ”, explains the expert.
Why are there still diseases without a vaccine?
Perhaps you are wondering: if it was possible to make an immunizer so fast against a virus that appeared a year ago, why do scientists simply not make vaccines for so many other diseases?
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In addition to the outbreak scenario helping to speed up the race, there are some specifics of the new coronavirus that have shortened the path. One of them is the low rate of mutations in Sars-Cov-2, which happen, but not to the point of hindering the development of the vaccine.
“It changes at a rate approximately four times less than HIV and twice less than the influenza virus, which causes the flu,” compares the epidemiologist.
Nor did the researchers spend so much time figuring out which part of the agent needed to be neutralized to prevent it from spreading to the body.
See: there is a specific protein in Sars-Cov-2 that binds to the cells of our body. It is called spike or spike. “This is the target of vaccines. And luckily, it was easy to identify her ”, says the professional.
In addition to virus mutations, the mechanisms of action of other infectious agents can make it difficult to create vaccines against them. “Malaria, for example, is caused by a protozoan that hides very well from the immune system”, exemplifies the deputy director of Sabin.
For non-infectious diseases, creating a vaccine is even more complicated, as they do not arise only because of an intruder (such as a virus or bacteria). We don’t have any approved type yet, just research, especially for cancer.
Vaccine safety has been tested
Despite the speed, all stages of studies of doses already approved against Covid-19 were fulfilled as mandated by the protocol, which is always the same. There are three phases of tests in humans, the third, in tens of thousands of people, the definitive one to certify safety and effectiveness.
“In fact, this phase was even more rigorous”, reveals Denise. Normally, regulatory agencies require only six weeks of observation by volunteers to check for adverse effects, which is the period they usually occur.
“In the United States, the FDA [Food and Drug Administration Agency, órgão regulador de medicamentos dos Estados Unidos] demanded that this time be extended to eight weeks ”, informs.
It is important to stress that there is a possibility of serious side effects appear now that mass immunization has started. However, the normal thing is that there are very few cases among millions of people – the risk of something like that is much less than that of dying when contracting Covid-19.
After approval, this risk is also monitored, in the so-called phase 4 of the studies, the “real life” test. So far, almost five million people have received vaccines against Sars-Cov-2 and the only worrying event was four serious allergic reactions in individuals who were promptly treated and recovered well.
“There were no shortcuts, no steps were taken to verify safety and effectiveness. Everything was done according to scientific rigor ”, concludes Denise.
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