Scientific study in Chile demonstrates high efficacy of third dose of COVID-19 vaccine

The government of Chile, which administered 3.6 million booster doses of the COVID-19 vaccine, released one of the first studies on the the effectiveness of an additional injection and pointed out that it reduces the risk of hospitalization by up to 96%.

“The study measured the effectiveness of the booster dose and delivered very promising results with high efficiency in preventing infections and hospitalizations”, Celebrated the President of Chile, Sebastián Piñera on the results of the research, which involved a total sample of 11.2 million people and analyzed the effectiveness of administering a third dose to 2 million people who had completed their vaccination schedule with Chinese Coronavac, from the Sinovac laboratory.

As explained by Dr Rafael Araos, the academic who led the study with Alejandro Jara, both advisers to the Under-Secretariat for Public Health of the Ministry of Health of Chile, all of the vaccines tested “significantly” increased their effectiveness in preventing symptomatic disease with an additional dose.

The main finding of the research shows that all vaccines used as booster doses, two weeks after their application, achieve markedly increased levels of effectiveness in preventing symptomatic COVID-19. In the case of CoronaVac, far exceeded estimates with two doses, increasing its effectiveness from 56% to 80.2%. In the case of Pfizer-BioNTech, it goes from 56% to 90%, and with AstraZeneca, it goes from 56% to 93%.

As it concerns hospitalizations, the third dose of AstraZeneca reduced its probability by 96%, that of Pfizer by 87% and that of Sinovac by 88%, compared to 84% of protection of those who did not receive it. Chile is a pioneer in the region in giving booster doses, with more than 3.6 million given to people over 55 and other groups who were vaccinated first, out of a population of 18 million. “Scientific evidence shows that vaccine protection begins to wane over time. This discovery, associated with the threat of the delta variant, led us to launch this massive process of reinforcement vaccination, ”added the President. While the WHO opposes this measure and maintains that it jeopardizes the equitable distribution of vaccines around the world, the pharmacological authorities of the United States recommend it for groups at risk and the European Medicines Agency supports that it is safe and effective for over 18 years. .

“These antecedents allow us to conclude that the decision to administer this supplemental vaccine to the diet was adequate and effective, as it allowed us to expand antibodies over time and extend protection to the most vulnerable population”Said Under Secretary of Health Paula Daza. The analysis was performed in people over the age of 16 who received CoronaVac as part of the two-dose schedule, which included 4.79 million people. Of these, 1.5 million received a boost from AstraZeneca, 371,592 Pfizer and 140,132 the same from Sinovac.

Meanwhile, to avoid hospitalizations for COVID-19, in Sinovac it fell from 84% to 88%, to 87% with Pfizer and 96% with AstraZeneca, the expert added. Chile has joined countries like the United States, Germany, France and Israel to give booster shots, despite a request from the World Health Organization (WHO) to wait until more people around the world receive their initial immunizations. Until, 13.5 of the 19 million inhabitants of the South American country have completed the initial vaccination schedule (nearly 89% of the population susceptible to vaccination) and more than 3.5 million have received the booster.

He also successfully inoculated 4 out of 10 children aged 6 to 11 with Sinovac or Pfizer. Daza also announced that from next week the booster dose campaign will begin for those who have completed the initial program with Pfizer, AstraZeneca and Cansino, clinical trial participants and those who have approved vaccines received at the ‘foreigner.

The Minister of Health, Enrique Paris, highlighted the first negotiations of the Chilean government to access vaccines from different laboratories and highlighted the relevance of this type of study which allows us to have evidence on the benefits of the vaccination campaign. “The importance of these studies in Chile lies in having local information on the effectiveness of vaccines to support decision-making, and thanks to the large number of people vaccinated and the availability of sources of vaccine. information in the country and also for our national vaccine registry, we were able to perform data reconciliations and advanced analyzes on the performance of vaccines applied in Chile to our fellow citizens ”, he stressed.

The Trans-Andean country has been under pandemic control for more than two months, with a PCR test positivity rate of around 1% and with more freedom than ever since the arrival of the virus, without quarantine or curfew and with bars, restaurants and sports centers open. Over the past week, the country, which reaches 1.61 million total infections and 37,500 deaths, has seen a slight increase in infections, which in the past 24 hours have reached 981.

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