A study within the study, which will expand the knowledge of science about the immunity generated by vaccines against Covid-19. This is how the new stage of Project S can be explained, a clinical trial that investigated the effectiveness of vaccination in controlling the Covid-19 pandemic and in the transmission of SARS-CoV-2 in the São Paulo municipality of Serrana.
The research, which started at 24th of july with the collection of blood samples from volunteers, will investigate the long-term immunity generated by CoronaVac, a vaccine from Butantan and Chinese pharmaceutical Sinovac. It will extend into the middle of next year with quarterly cycles in October 2021, January and April 2022.
It is a long process, but necessary, as there is still no certainty about the long-term immunity provided by vaccines. “We don’t have a consensus in the literature on how the coronavirus works, how long it lasts, whether there will be a vaccine every year, if not. That’s why this research is important”, emphasizes Gustavo Volpe, a physician at the Serrana State Hospital and principal investigator of the new Project S cycle.
Each cycle will last four days and will involve the collection of blood from the volunteers. By analyzing the samples, Butantan will be able to observe the evolution of the immune response, especially in the elderly population. The first cycle of the research, started now, takes place three months after the vaccination of the population of Serrana – the collective immunization of the first stage of Project S showed that CoronaVac is 80% effective against symptomatic cases, 86% against hospitalizations and 95% against deaths by Covid-19.
“We relate immunity to antibody production, but cellular immunity plays an important role in the response to the coronavirus. This assessment is quite difficult to measure. It is necessary to see the cellular activity, that is, to measure the metabolic activity, to test the expression of some types of receptors in the cells. It has many shapes. It will be a very complete evaluation”, reveals Volpe, referring to the so-called “cellular memory”.
The collected samples are sent to the virology sector of the Hospital das Clínicas in Ribeirão Preto, processed and tested. To assess the memory generated by the vaccine, one of the analyzes involves putting the sample in contact with SARS-CoV-2 and seeing if the virus is able to multiply. Tests will be carried out with different variants, such as alpha (B.1.1.7, from the United Kingdom), gamma (P.1, Amazon) and delta (B.1.617.2, Indian). In addition, positive samples are sequenced to find out which variants circulate in the city and the behavior of the vaccine against them.
Three months later, it starts all over again. Thus, it is possible to follow the evolution of the organism in fighting the disease. “This stage of the project assesses how many people seroconverted the vaccine [that is, developed antibodies to defend themselves against the infection] in the real state. We have phase 1 and 2 controlled studies of CoronaVac that demonstrated a high rate of seroconversion,” explains Volpe. “We are going to study the issue of cellular immunity in the population, the history of the evolution of antibodies. In this way, we are going to see ahead how the trajectory of antibodies and cellular activities was”, completes the doctor.
The new phase of Project S will be monitored by the Ethics Committee of the Hospital das Clínicas, Faculty of Medicine of Ribeirão Preto, University of São Paulo.