COVID-19: The Lancet published an Argentine study on the importance of heterologous vaccination and third doses

The coronavirus pandemic continues to advance and in recent days infections have increased globally. Almost two million new infections and 5,300 deaths from COVID-19 were recorded yesterday, which reaffirms the need for vaccines to prevent the severe forms of this disease that has been plaguing the world for two years.

Although only 56 per cent of the world's population is vaccinated with the complete two-dose schedule of the vaccine, this is not enough. Scientists have proven that the antibodies generated by the body after receiving the vaccine decrease with time, so it is essential to apply a third dose or booster dose to keep the coronavirus at bay and thus avoid serious infections and hospitalizations.

The research entitled Evaluating COVID-19 vaccines in the real world, examined the effectiveness of Sputnik V, AstraZeneca and Sinopharm vaccines in 1,282,928 people aged 60 and over.

The extensive Argentine scientific study was published in the prestigious international journal The Lancet Infectious Diseases. The report, carried out during a year of vaccination in the country, provides clarity and adds key data to understand the need for the application of a third dose of vaccine, after having received the initial two.

“The scientific study we did as a team indicates that two doses of the coronavirus vaccine provides limited protection for the Ómicron variant. The data indicate that for all vaccines there is a great benefit with the third dose to counteract infections with this variant. To protect against Ómicron, it is essential that adults apply the booster dose, at the right time. Several studies are strongly demonstrating that the third dose increases the level of neutralizing antibodies that block this new variant in a very significant way,” molecular virologist Andrea Gamarnik, leader of the new scientific study and senior CONICET research, told Infobae.

The immune response induced by two doses of vaccination against the Ómicron variant of SARS-CoV-2 is not optimal, according to the study carried out by Gamarnik and scientists from CONICET, the Leloir Institute and INBIRS carried out in conjunction with the Ministry of Health of the Province of Buenos Aires. They arrived at this result after analyzing for a year the immune response induced by the Sputnik V vaccine in 100 volunteers.

“After a year of follow-up of volunteers who received the Sputnik V vaccine, we presented these results, which are the continuation of another previous work that we published 6 months after starting. At that time, Ómicron did not exist and we did the study with all the variants that were circulating in the country at that time (Alfa, Gamma, Delta, Lambda). If we compare the ability to inhibit the infection of the different variants by the antibodies generated by the Sputnik vaccine, we see that the one that escapes antibodies the most is Ómicron. For this reason, applying the third dose at a time when Ómicron is the most widely circulated variant in our country, as is the case today,” said Gamarnik, head of the Molecular Virology Laboratory of the Leloir Institute Foundation (FIL).

“The data are excellent: the effectiveness in preventing deaths after two doses of either vaccine in that time period was greater than 85% (93.1% with Sputnik V; 93.7% with AstraZeneca and 85% with Sinopharm),” said the National Minister of Health, Carla Vizzotti, following the publication of the Argentine studio at The Lancet.

During the period from January 2021 to January 2022, the team of scientists periodically measured the level of antibodies to SARS-CoV-2 using the COVIDAR IgG test, developed by CONICET researchers. In addition, using viral cultures, it carried out measurements to evaluate the ability of será from vaccinated individuals to neutralize, or prevent infection, by the original SARS-CoV-2 variant (B.1 lineage isolated in Wuhan, China) and by the omicron variant, isolated and characterized in our country. While serum samples showed the presence of high levels of neutralizing antibodies directed against the original variant following the application of the vaccination scheme based on the administration of two Sputnik V vaccine, the researchers observed a dramatic drop in neutralizing capacity compared to the omicron variant.

The published work is the culmination of a study started a year ago, when the mass vaccination program began in Argentina. The publication includes information based on the analysis of blood samples from 100 volunteers vaccinated with two doses of Sputnik V vaccine, which were studied over a year. Volunteers received both doses of vaccine between January and February 2021.

“Ómicron has a high capacity to evade the immune response set up by the vaccinated individual. This is expressed in a marked decrease (more than 60-fold) in the ability of vaccine-induced antibodies to block Omicron infection when compared to that ability to block the original B1 variant (which is no longer circulating in our country),” said Gamarnik. This “defect” is largely overcome when the vaccinated individual receives a third dose of vaccine.

Jorge Geffner, senior researcher at CONICET at the Institute for Biomedical Research on Retroviruses and AIDS (INBIRS), which reports to the Faculty of Medicine of the UBA and CONICET, also led the study, indicated that “booster vaccination that combines different vaccine platforms (e.g. Sputnik V with Pfizer/BioNTech, Moderna, Sinopharm or AstraZeneca) would represent a highly effective option to accelerate vaccination and increase levels of neutralizing antibodies against the Omicron variant.”

“In the field of vaccination against COVID-19, there are two major challenges: the emergence of new variants and the durability over time of the defense mechanisms conferred through vaccination. Depending on these two variables, vaccination schedules will have to be adjusted and, in this regard, the study carried out by us and other similar ones carried out worldwide is of particular relevance. Vaccination against COVID-19 is the great tool we have in order to crush the SARS-CoV-2 pandemic. We will need to continue studying how to adjust and improve current vaccination schedules, in order to optimize the protection of the population against this new virus,” added Geffner.

According to experts, the study benefited from the valuable contribution of the Ministry of Health of the Province of Buenos Aires. “In the province of Buenos Aires, every decision taken regarding vaccination was evaluated on the basis of international evidence, and the local evidence generated by studies such as this one that we carry out in conjunction with prestigious research institutions,” said fellow study author Nicolás Kreplak, clinical physician and Minister of Health of the Province of Buenos Aires.

“Once we had the results of this newly published study, which began with the first population group vaccinated in December 2020, we were able to assess the importance of giving booster doses in the general population and define the best window of time for this. This study is complemented by others that analyze effectiveness in real life, at all times of the pandemic and with strict epidemiological surveillance. Everyone who has not yet applied the booster dose and it has been 4 months since the second dose, it is important that they are going to get vaccinated,” added the minister. According to Kreplak, the results of the research show that after 6 months there is a significant drop in the neutralizing capacity of the antibodies generated by vaccination against the omicron variant, indicating the need for a booster dose between 4 and 6 months to ensure maximum protection.

Marina Pifano, PhD in science and technology, biotechnology advisor to the Ministry of Health of the Province of Buenos Aires and general coordinator of this study, stressed the importance of articulating between different institutions. “The speed with which this project was carried out in order to study locally the effect of vaccines on our population allowed us to generate our own evidence for real-time decision-making according to the times imposed by the dynamism of the pandemic,” he said.

The study shows great coordination of work between the Ministries of Health and Science and Technology to generate useful information for the design of vaccination strategies in our country, Gamarnik said. “We are proud to be able to work transversally, cooperatively and in solidarity, incorporating health professionals and researchers from CONICET. This is one of the lessons learned from the pandemic. This work is very important for making health decisions as it provides rigorous information on the duration of antibodies with the sputnik vaccine per year and on the escape of the different variants, now in particular Ómicron”, concluded the specialist.

The other authors of the study are Lautaro Sánchez, Santiago Oviedo Rouco, Diego Ojeda, Carla Pascuale, María Mora González López Ledesma, Pamela Rodriguez, Esteban Miglietta and Andrés Rossi, from CONICET and FIL; Ana Ceballos, Facundo Di Diego Garcia and Bianca Mazzitelli, from INBIRS. Members of the FIL Serology and Vaccines Laboratory and professionals from public hospitals in the Province of Buenos Aires also participated.

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