(Montevideo) A third injection of the German-American vaccine Pfizer-BioNTech after two injections of the Chinese vaccine Coronavac increases the level of antibodies against COVID-19 by 20, according to the preliminary results of a study carried out in Uruguay where 24% of the population had access to this vaccination schedule.
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Since the beginning of March, researchers from the Institut Pasteur de Montevideo and the University of the Republic (Udelar) have been carrying out a research project to study the evolution of the levels of antibodies against SARS CoV-2 depending on the vaccines and doses administered.
The study, which involves more than 200 volunteers, is to last two years and provides for regular serological examinations.
A subgroup of 57 people who received two doses of Coronavac then one dose of Pfizer-BioNTech, had four blood tests: one before vaccination, another 18 days and then 80 days after the second dose of Coronavac, and a final one. 18 days after the third dose of Pfizer-BioNTech.
After the first blood test, none of the participants had specific antibodies against the virus. After the second, 100% of the volunteers had antibodies, but at varying levels.
Following the third, there was a general decrease in antibodies compared to the previous test.
Finally, after the fourth examination, all participants showed an increase in the level of antibodies on average 20 times greater than the results of the previous blood test.
Sergio Bianchi, a researcher at the Institut Pasteur, stressed at a press conference that these were “preliminary results” and that studies would continue to assess the length of time during which the antibodies persist.
The Uruguayan Minister of Health, Daniel Salinas, welcomed the results of the study, stressing the importance of evaluating “with scientific tools” the vaccine mix – inactivated virus vaccine + messenger RNA vaccine – such as ‘it is implemented in Uruguay.
In this country of 3.5 million inhabitants, 72% of the population is vaccinated according to the full protocol of Coronavac, Pfizer or Astrazeneca, and 24% have already received a third booster dose.
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