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In the race to find an alternative to curb the pandemic of COVID-19Thousands of volunteers around the world were enrolled in various clinical trials of vaccines. In Peru, one of the countries most hit Due to the health crisis, many people made their time and health available to test the vaccines in development.
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One of the trials carried out in the country is that of the Oxford / AstraZeneca vaccine, which has with 1,463 Peruvian volunteers. In total, the investigation, which was also carried out in Chile and the United States, enrolled 32,451 people.
One group received the vaccine and another received a placebo, with the objective of determining the efficacy of the viral vector immunizer AZD1222 (ChAdOx1 nCoV-19) in prevent the occurrence of symptomatic and severe COVID-19 15 days after the second dose in adults and older adults. The phase III clinical trial was double blind and randomized; that is, neither the participants nor the researchers knew which group they belonged to.
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Now a recent study published in the journal The New England Journal of Medicine, one of the most important medical publications in the world, reports the results of these tests: the overall efficacy of the vaccine was 74%.
According to the article, the trial was not designed to determine efficacy by country, but overall efficacy was. This is due, among other factors, to the difference in the number of participants per region.
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“There are two factors to take into account: one, effectively, is the number of participants and two is the recruitment time, which in Peru and Chile it was much shorter […] There is no precise efficacy by country, but I believe that the laboratory has been as transparent as possible in exposing the data of each country ”, says the Peruvian doctor Alfredo Guerreros, one of the signatories of the study.
The trial included healthy people over 18 years of age with comorbidities (cancer, diabetes, HIV, etc.); 60% had more than one of them. In addition, people with a high degree of exposure to contagion and older adults were included.
“At the time that we have carried out the recruitment of patients, Peru was at a high level of cases and we had no prevention alternatives [para el COVID-19]″, clarifies the researcher.
The volunteers will be in follow-up for two years, in order to monitor their health status after the application of the vaccine, which is currently the third most used in the immunization campaign against COVID-19.
Overall, the vaccine was safe for the participants. Among the most common adverse effects, the general malaise, headache, injection site pain, and fatigue. All of them short-lived.
The incidence of serious adverse effects was low: 0.5% of the total, both in the placebo group and the vaccine group.
As it is known, the AstraZeneca vaccine was questioned by some thrombosis cases [coágulo sanguíneo que puede llegar a ser mortal] after the injection, which has not yet been directly related to the vaccine.
The authors clarify that within the framework of this study “There were no cases in any of the groups (placebo and vaccine) of trhombosis with thrombocytopenia, tcerebral venous sinus rhombosis or venous thrombosis in unusual locations ”.
The effects of interest recorded, which were treated medically, were significantly rare and presented in a similar proportion in both groups. They were registered from neurological, vascular and hematological problems, but they only affected between 0.1 and 0.5% of the participants.
It is important to clarify that in a clinical trial an adverse event is any incident that is detrimental to the health of the volunteer, which has not necessarily been caused by the product under investigation. This means that every health problem in a volunteer will be recorded, but this may have another cause, such as an accident, for example.
“From our experience in the research center [de la Clínica Internacional] that we direct -which was the one that recruited the most in Peru, 580 patients-, no patient had a serious adverse effect. Some patient had local allergic reactions, such as redness and even some cellulitis, which I would consider to be the most serious, but vaccine-associated thrombocytopenia, which is the most serious event related to this vaccine, there was none “, the researcher details. Three research centers were included in the country.
During the investigation period, seven deaths were recorded in participants in the AZD1222 group and seven in the placebo group. “The researchers considered that no deaths were related to the vaccine or the placebo. There were no COVID-19 related deaths in the AZD1222 group (vaccine), and there were two COVID-19 related deaths in the placebo group “, the authors note.
The variants of SARS-CoV-2, the virus that causes COVID-19, detected in the study were Alpha, Beta, Epsilon and Iota. Delta was not yet predominant.
In Peru, about 30 million doses of COVID-19 vaccines and more than 13 million people have the complete scheme, representing 47% of the target population. As for the AstraZeneca vaccine, more than 1.2 million doses have been applied; It is the third most used in the country.
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