Booster dose of COVID-19 vaccine stimulates immune system response

40% of the world’s population has already received at least one dose of the COVID-19 vaccine. But in low-income countries, access is still low: it does not exceed 2% of the population. Meanwhile, in countries most advanced in their immunization plans, attention is shifting to the decision to give a booster dose – that is, a dose after completing the schedule – to the population for better protect yourself against new variants of the coronavirus. worry. Now in the magazine The Lancet A study has been published which suggests for the first time that the booster dose not only increases the level of antibodies but also the level of cellular memory.

The research was conducted by Teresa Lambe, Andrew Pollard, Amy Flaxman, among other scientists who are part of the COVID-19 Vaccine Trial Group at the University of Oxford, UK. They evaluated what happened to the vaccine developed by this university and the AstraZeneca company. They also confirmed that increasing the interval between the first and second dose of COVID-19 inoculants results in a larger increase in antibody levels.

“COVID-19 vaccine shortages raise concerns that immunity may be compromised in some countries as the interval between the first and second dose lengthens. On the contrary, countries that do not have supply limitations are considering the possibility of administering a third dose, ”the researchers indicated at the start of their work. They explained what they did: The persistence of protection after a single dose of the vaccine, immunity after a prolonged interval of 44 to 45 weeks between the first and second dose, and the response to a third booster dose given between 28 and 38 weeks after the second dose.

“The study published in The Lancet magazine confirms that increasing the time between the application of the first and second doses of the AstraZeneca COVID-19 vaccine improves the effectiveness of the inoculant to reduce the risk of complications and death due to to infection. That is to say, verifies the benefit of the extended interval which had been adopted as a measure in vaccination plans in England, Canada and Argentina, among other countries ”, he declared Infobae Doctor Javier Farina, from the Argentinian Society of Infectology and Head of Infectology at the Hospital de Alta Complejidad Cuenca Alta, in Cañuelas, province of Buenos Aires.

“The work is also evaluating what is the response of the third dose. They found that the booster dose increases the level of circulating antibodies and the cellular response. Although this booster dose does not increase the cellular response to very high levels like the second dose does ”, Dr Farina said. “The study also shows that the first dose of the vaccine is important to protect the population. For this reason, we must work with all regions of the world to ensure that the entire population has real access to the first dose in the context of the emergence of worrying variants of the coronavirus, ”he said.

The Oxford researchers’ trial is a substudy building on the main work they did to assess the vaccine in 2020 before it was cleared by the drug and vaccine regulator for emergency use. Between March 11 and March 21, 2021, 90 participants were enrolled in the third dose booster substudy, of which 80 were evaluable for reactogenicity, 75 were evaluable for antibody assessment, and 15 were evaluable for responses T lymphocytes.

Among participants who received a third dose of the vaccine, antibody titers (measured in 73 [81%] participants for whom samples were available) were significantly higher 28 days after a third dose than 28 days after a second dose, the researchers reported. In addition, the responses of T lymphocytes – which are cellular memory – were also improved on the 28th day after the third dose. They clarified that “the reactogenicity after a late second dose or a third dose was lower than the reactogenicity after a first dose”.

Whether or not to give a third dose and to whom to apply it is one of the current debates regarding the pandemic. So far, the WHO recommends prioritizing the first and second doses to protect more people around the world. The COVID-19 pandemic has killed more than 4.4 million people worldwide. People who had to be connected to mechanical ventilators have the worst prognosis: 70% do not overcome the disease.

In Argentina, according to official data from the National Ministry of Health, 33% of the population has already been vaccinated with the first and second doses against COVID-19. As of September 2, 43,221,929 claims had been made, 28,100,621 people had received one dose and 15,121,308 people had completed both doses.

After the meeting of the Federal Health Council (Cofesa), the Minister of Health of the Nation, Carla VizzottI confirmed this Tuesday that the government will assess from November the possibility of applying a third dose of the vaccine to immunocompromised people. “To arrive in September with the second doses, in October with the adolescents and from November to assess whether we are able to do a booster in people who have certain health conditions and are immunocompromised,” he explained. at the end of the meeting with the ministers of health of the 24 jurisdictions.

“Vaccinating, vaccinating and vaccinating is what needs to be done to stop the Delta variant and others. The slow arrival of the Delta variant so far gives us the opportunity to do what we are doing, ”explained Tomás Orduna, infectious disease specialist at Muñiz Hospital and member of the consultation team advising the government. during the current pandemic.

There are different positions regarding the third doses. Yesterday, the European Center for Disease Prevention and Control (ECDC) said there was no urgent need to give booster doses of COVID-19 vaccines to people according to the full schedule, citing data on the effectiveness of injections.

Instead, last Monday, Israel became the first country in the world to offer the booster dose of the COVID-19 vaccine to anyone over the age of 12. The intensification of vaccination procedures occurs in the midst of the fourth wave of infections in this country. According to reports from health authorities, more than two million people have already received the booster dose since its authorization.

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