One Brazillian town is making a huge step forward in a time of both a global pandemic and massive global anti-vax movements. With the help of local health research centers and volunteers, the town of Serrana has already vaccinated over 95% of its adult population with the Chinese CoronaVac vaccine. This is not only great news for the townspeople of Serrana but it also offers a fantastic opportunity for researchers and the public worldwide to see just how effective mass immunization can be.
Is it voluntary?
One key issue that pops into most people’s minds when they hear about “mass vaccination” is whether it’s voluntary or not. With millions of people worldwide rejecting vaccination efforts, the news that 95% of the population of a town is getting vaccinated all at once raises some questions.
And the answers are both conclusive and positive – the citizens of Serrana are participating in the vaccination voluntarily. In fact, far-right Brazilian president Jair Bolsonaro has been talking against vaccines in general for months (1) and is especially adamant in his position against CoronaVac. So, any worries about involuntary vaccinations don’t seem particularly reasonable.
How was the whole process organized?
The picturesque town of Serrana is situated in southeast Brazil and consists of only 45,000 people, around 30,000 of which are adults. It’s also very close to an important public health research center, the University of São Paulo’s campus in nearby Ribeirão Preto (2).
The mass vaccination process is done with the help of both São Paulo’s campus, as well as other institutions such as the Federal University of Espírito Santo (3). Together with local authorities and volunteers, researchers have been working for months to persuade the ~30,000 people in Serrana of the benefits of the vaccine and that of mass vaccination in particular (4).
The mass vaccination project has been dubbed Projeto S (5) and its purpose is to help the people of Serrana as well as to measure the real-world effectiveness of the CoronaVac vaccine. The results are especially crucial in relation to the Brazillian P.1 strain of Covid-19 which has been shown to be overly invasive even against people with Covid-19 antibodies (6) (7).
Another goal of the researchers’ study of the vaccination efforts (8) is to gauge just how effective the vaccine is for protecting not just those who had taken the two quick jabs but also the unvaccinated around them. Marcos Borges, project coordinator and director of the Serrana State Hospital (9) describes it as a question of “Whether vaccinated people protect the unvaccinated, how long does their immunity last, and what variants are circulating. We’ll finally be able to observe how a large set of people respond to the vaccine in real-world conditions.”
Projeto S is equally important for everyone else around the world for the same reason. Ethel Maciel, an epidemiologist at the Federal University of Espírito Santo (10) says that
“Projeto S may be the best way to understand the effectiveness of vaccination against COVID-19 in the short and medium terms.”
“This is especially important because we don’t know when we will have most Brazilians vaccinated,” she added.
Brazil is also the perfect place for such research for other reasons. When the project was initiated in February 2021, the researchers from Instituto Butantan, one of the research facilities and a vaccine maker in São Paulo state that’s sponsoring the project (11), set the goal of Projeto S at 80% of the population.
“We took into account that Brazil has a long tradition of good adhesion to vaccination, so we knew these 80 percents were within reach,” said Borges.
That goal was quickly exceeded, however. As of mid-April 27,722 of the ~30,000 adult citizens of Serrana had received the first dose of CoronaVac and the astonishing 27,160 of them had gotten the second jab too. That means that 95.7 of Serrana’s adult population was fully vaccinated just two months after Projeto S was launched.
This is great for the project as well as for the townspeople of Serrana as 80% may have been insufficient for complete herd immunity given that Projeto S used CoronaVac.
How does the Chinese CoronaVac compare to Western vaccines?
The CoronaVac Covid-19 vaccine is developed by the China-based Sinovac Biotech company (12). This vaccine works on a different principle than the popular in the west mRNA Pfizer-BioNTech and Moderna vaccines and even the Oxford-AstraZeneca vector vaccine.
Instead, CoronaVac uses an inactivated or “killed” version of the SARS-CoV-2 virus. This inactivated version is incapable of causing any illness in the vaccinated person but still teaches their immune system to recognize the bio structure of the virus and develop the necessary tools for fighting against it.
While there are benefits to this method, there is also one major drawback – this vaccine has less efficacy than other vector or mRNA vaccines. During the Phase III clinical trials that Sinovac Biotech performed in São Paulo (13), CoronaVac displayed only a 50% efficacy two weeks after the second dose. This percentage passes the threshold set by the U.S. Food and Drug Administration as a baseline for considering the authorization of emergency use COVID-19 vaccines in the United States (14), however, it’s still notably lower than the 95% efficacy in the clinical trials of both the Moderna and Pfizer mRNA vaccines.
This doesn’t mean that the CoronaVac is “not good enough” to achieve the necessary results, however – it just means that more people need to be vaccinated for sufficient protection to be ensured both for the vaccinated and for those that remained unvaccinated.
Ernesto Marques, a virologist at the University of Pittsburgh (15), explains it like this:
“What is the difference between a vaccine that has 95 percent of individual efficacy and one that has over 50 percent? You’ve got to vaccinate 80 or 85 percent of people with the former to have the disease under control and must vaccinate everyone with the latter to have the same result.”
Fortunately, that’s almost exactly what Projeto S has achieved in Serrana.
The early results
The local media in Serrana is already reporting that the rate of new daily infections has dropped four times in a month since the end of March while the share of severe cases has dropped by 70% (16).
Unfortunately, six of the over 27,000 vaccinated adults still died from Covid-19 in the period between mid-February and mid-April, according to the state government of São Paulo (17).
There don’t appear to be any complications caused by the vaccine and the number of Covid-19 victims would’ve been much higher without it. Five of the six deaths had received only one dose too while the sixth had shown Covid-19 symptoms shortly after his vaccination which means that he had been infected before the vaccine’s immunity could be developed. Of the unvaccinated population of the town, 14 more people died of Covid-19 in the same period.
The positive test results have also dropped in the last couple of months. As Nurse Glenda de Moraes from the Serrana’s Santa Casa Hospital (18) and the city’s Basic Healthcare Unit puts it:
“[The positive test results have dropped] to less than 20 percent [per day], way less than the 30 to 40 percent of positives we had before.”
It’s not yet time for celebrations, however, says Borges. “We are still studying it and when we have the results, we’ll be able to affirm for sure if these events are related,” he says.
Projeto S is expected to continue for at least a full year, until the spring of 2022. This would include close monitoring of the statistics coming out of Serrana and the general condition of all vaccinated and unvaccinated adults. The need for additional vaccination is also yet to be determined as the exact longevity of the vaccine’s immunity isn’t certain. With ~15,000 of Serrana’s 30,000 adults commuting to large distances outside of town for work almost every day, it’s also interesting what effect the project will have on neighboring communities.
Still, despite the fact that there are many questions left unanswered, the residents of Serrana seem very relieved in all the interviews they’ve given since the start of the project. One such resident is Juliana Elaga, the very first citizen of Serrana to be vaccinated.
“I suffered a lot with the pandemic,” Juliana said. “And the vaccination was a really emotional moment for me. I felt truly relieved after the second jab. Even still adopting social distancing and mask-wearing, my heart is more at rest.”
Her 8-year-old son Petras also adds that
“Mom used to wear two masks at once and rub her hands with alcohol-gel all the time. Now she seems a little more normal and not so worried all the time.”