Butantan study shows higher efficiency of CoronaVac

It also found 99% of vaccinated people in Serrana seroconverted

Published in 22/10/2021 - 14:28 By Agência Brasil - São Paulo

The study on the efficiency of vaccine CoronaVac, being carried out by Butantan Institute analyzing the immunity of the population of Serrana, São Paulo, found that 99 percent of the people showed seroconversion—i.e. they have developed the antibodies against a COVID-19 infection—three months after receiving the second dose of the inoculation.

These are the first figures from the Butantan research on the city that saw the execution of Project S—whereby all of the population aged 18 and above were immunized, in February.

The indicator was higher than the results from the clinical trials from phases one and two of CoronaVac, showing seroconversion at around 97 and 98 percent, respectively, depending on the dose.

According to the institute, in addition to proving once again the durability of the protection brought about by the vaccine, the study is special for analyzing the antibodies and the cell immunity in the real world—which thus far had only been conducted in a laboratory.

The preliminary data are based on the first stage of the serological assessment, conducted in July and August, when samples were collected from 3,903 volunteers in Serrana. The second stage of the serological assessment is in progress.

A scientific article evaluating the immunity of those vaccinated under Project S is expected to be published in a few months. “We now have the number of antibodies in adults and the elderly. The article will disclose the serological variation over these last three months,” said Dr. Gustavo Volpe, one of the coordinators of the study and a technical director at State Hospital of Serrana.

Serrana - Prefeitura Municipal de Serrana.

The elderly

The elderly people who have received the booster dose have joined the study in large numbers, and this should be reflected in the exams. “It will bring interesting data. We see that titration [the concentration of antibodies in the serum/plasma] sinks as people get older. The titers in their serology tend to be lower than their counterpart in younger people, but, with the booster dose, we’ll see if it’s more or less the same,” Volpe pointed out.

In September, the people of Serrana aged 60 and older started receiving an additional dose of CoronaVac as a way to optimize the general immunity against SARS-CoV-2 and increase the protection against the Delta variety, which was starting to become prevalent in Brazil.

Lower indicators

In May, preliminary data from Project S showed that the immunization of the adult population in Serrana led to symptomatic cases of COVID-19 to plummet 80 percent, hospitalizations 86 percent, and deaths 95 percent. According to Volpe, the number of COVID-19 hospitalizations in the city continues low, but protection measures must be upheld.

“What we’re witnessing in Brazil today, in terms of the reduction in hospitalizations, cases, and transmission, we saw in Serrana in May and June. Observing what takes place in Serrana is crucial to see what will happen in Brazil. This is why the city is such an important laboratory. It’s where we can really see the effect of the vaccine,” he added.

Translation: Fabrício Ferreira -  Edition: Nádia Franco / Nira Foster

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