Fiocruz Mato Grosso do Sul and Sabin research fractionated booster dose of COVID-19 vaccine

A research conducted by the Sabin Vaccine Institute and by Fiocruz Mato Grosso do Sul will evaluate the possibility of fractioning booster doses of vaccines for COVID-19. The research shall reveal if smaller doses can offer the same immunological response with fewer adverse reactions. It would allow to multiply the amount of vaccines, especially in poor countries, and guide new immunization strategies. According to Sabin Institute, only 17.4% of the population of low-income countries were vaccinated against COVID-19, while in high-income countries the index is 72%.

The study will analyze fractioned booster doses of COVID-19 vaccines (photo: Bio-Manguinhos/Fiocruz)

For the research, the institute received US$ 6.3 million (R$ 32.7 million) from the Coalition for Epidemic Preparedness Innovations (Cepi), an international organization that funds research projects to accelerate the production of immunizations. The institute selected two countries: Brazil and Pakistan. In each one of them, 1,440 people will participate in the research, receiving the vaccines Pfizer (full dose, half or a third), AstraZeneca (full dose or half) and Coronavac (full dose), being monitored for six months.

“In the development of vaccines, the dose is determined in the initial stages, balancing the effectiveness with possible collateral effects, until we get an effective dose with minimal collateral effects”, says Denise Garret, vice-president of Applied Epidemiology of the Sabin Institute of Vaccines. “With the pandemic, there was a huge pressure to achieve an effective vaccine. We were in a situation where we could not take the risk of failing. But we are now in a moment that we have the opportunity of optimizing this dose.”

Other three projects in the world also received funding from Cepi for studies with the vaccines against COVID-19.

A solid partnership

Among the reasons for picking Brazil and Pakistan are the vaccines applied in both countries, the availability of patients who still did not take booster doses and solid partnerships in the scientific field. Denise Garrett highlighted the need for the research to be conducted with the severity needed and emphasized the work of the Fiocruz Mato Grosso do Sul research group and of the Pakistani University Aga Khan.

In Campo Grande, the study will be conducted in partnership with the Federal University of Mato Grosso do Sul (UFMS) and the Municipal Health Department. Julio Croda, a researcher of Fiocruz Mato Grosso do Sul, explains that, with the help of community agents, there will be an active search for people who still did not take the booster dose, especially in the areas of the city with lower vaccine coverage. The household visits may occur by the end of the day or on the weekends to meet those who could not take the vaccines for difficulty in accessibility or for misinformation. “If we can approach then at home, we can talk, explain what the project is about, the benefits of the vaccine”, explained the researcher.

There will be four visits: inclusion (in which the person receives all information, signs the adhesion form and receives the booster vaccine), a visit after 28 days, three months and six months, always collecting blood. If, during this period, the individual contracts COVID-19 or has any reaction, he will also receive medical care. It is a blind study in which most part of the team will not know which vaccine is applied. And there will be a mobile unity at the neighborhood with a physician, a nurse and a pharmacist to handle the vaccine, to be close to the patients if they need anything”, stated Croda.

Background with polio and yellow fever

The study of fractioning the doses is not anything new. In the past, the World Health Organization has also recommended the fractioning of vaccines for polio and yellow fever, in face of the shortage of immunizations.

The vice-president of the Sabin Vaccine Institute highlights that the fractioned booster dose can have fewer collateral effects and, therefore, increase the acceptance of immunization. She highlights another issue: the appearance of variants. “With new variants, which bring the need for booster doses, it is very important to use the smaller dosage possible. If the dosage is smaller, there will be more tolerance, and possibly more booster doses can be applied”, she explained.

If the research proves that the fractionated doses can offer similar protection to the full dose, the amount of vaccine available increases, leading to new strategies of vaccination and allocation of immunizers, at a moment in which a lot of countries still do not have them in sufficient amounts, highlights Denise Garrett. The idea is that the research helps the decision-makers.

“This is a short project, of a year at maximum, from recruitment to monitoring, to generate a fast response. And it should benefit more other countries [that have a lower vaccine supply] than Brazil, especially poorer countries, in understanding that the fractionated dose is viable”, concludes Croda.