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The World Health Organization (WHO) does not expect a comprehensive vaccination against Covid-19 until mid-2021, a spokeswoman for the organization said on Friday, emphasizing the importance of rigorous efficacy and safety controls. vaccinations
None of the vaccine candidates found in advanced clinical trials has so far shown efficiency “clear signal” at a minimum level of 50% wanted by WHO, spokeswoman Margaret Harris said, according to Reuters.
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“We really don’t expect to see widespread vaccination until the middle of next year,” Harris said during a United Nations (UN) briefing in Geneva.
Russia gave regulatory approval for a Covid-19 vaccine, called “Sputnik V,” in August after less than two months of human testing, leading experts to question its effectiveness and safety. At the time, the lack of published studies on Russian tests generated mistrust in the international community.
This Friday the results of the phase 1 and 2 tests of the vaccine were published in the scientific journal “The Lancet”, which is one of the most important in the world.
On Thursday (3), public health officials from the US and Pfizer said the vaccine could be ready for distribution by the end of October. This deadline is slightly before the US presidential election on November 3, in which the coronavirus pandemic should be a major factor among voters deciding whether US President Donald Trump will have a second term.
“This Phase 3 [de testes clínicos] it has to be longer, because we need to see how truly protective the vaccine is and we also need to see how safe it is, “Harris said, without referring specifically to the possible vaccine.
All test data must be shared and compared, he said. “A lot of people have been vaccinated and what we don’t know is if the vaccine works. At the moment, we don’t have a clear signal whether or not it has the necessary level of efficacy and safety.”
Steps to produce a vaccine
It takes time to produce a vaccine. The fastest developed so far was the mumps vaccine, which took about four years to be licensed and distributed to the population.
Before starting the tests in volunteers, immunization goes through several phases of preclinical experimentation (in the laboratory and with guinea pigs). Only after its safety and efficacy have been evaluated do human trials begin, the so-called clinical phase, which are three:
Phase 1: It is a preliminary evaluation of the safety of the immunizer, performed with a small number of healthy adult volunteers who are closely monitored. It is at this time that the type of response that the immunizer produces in the body is understood. It is applied to dozens of participants in the experiment.
Phase 2: In the second phase, the clinical study is expanded and has hundreds of volunteers. The vaccine is given to people with characteristics (such as age and physical health) similar to those for whom the new vaccine is intended. In this phase the safety of the vaccine, immunogenicity (or protective capacity), the dose and how it should be administered are evaluated.
Phase 3: Large-scale trial (with thousands of people) that should provide a definitive evaluation of its efficacy and safety in larger populations. In addition, designed to predict adverse events and ensure the durability of protection. Only after this phase can a medical history be taken.
