[ad_1]
CoronaVac, the first vaccine to have an emergency use request made to Anvisa (National Health Surveillance Agency), reached 78% effectiveness, according to the tests carried out by Butantan in phase 3 of the investigation. Despite the rate, which is considered good, success in eradicating COVID-19 depends on more factors.
Experts heard by Twitter explain that the efficiency of a vaccination is also calculated taking into account aspects such as the target audience and the vaccination coverage achieved. That is, vaccinate the right people in sufficient quantity to stop the virus.
Some of the vaccines included in the PNI (National Immunization Program) calendar are even less effective than CoronaVac, but they still produce great collective impacts. “No vaccine is 100% effective,” explains Isabella Ballalai, vice president of SBIm (Brazilian Society for Immunization).
Over the years, Brazil has managed to eliminate or make infectious diseases less incidental thanks to vaccination.
This was the case with smallpox in 1977. Or with the famous droplets against the transmission of poliomyelitis -which had the last case in the country in 1989. Also due to immunizations, cases and deaths from yellow fever and influenza, for example, with vaccinations of public-target or through campaigns. Diseases such as measles have returned, not because of the lack of effectiveness of the vaccine (which reaches 95% to 97% in the second dose), but because of the low vaccination coverage.
In March of last year, Twitter revealed that the country had not reached any targets for major vaccines in 2019. According to the ministry, the drops have occurred since 2011.
Delayed twice, CoronaVac results expected from December 15
Image: NELSON ALMEIDA / AFP
CoronaVac Effectiveness Outperforms Common Flu Vaccines
A vaccine known to Brazilians with less efficacy than CoronaVac is influenza (flu), which is administered annually to the elderly and priority groups. Prevents flu strains, such as H1N1, but it has an average effectiveness between 60% and 70%. The value, however, it varies over the years and has reached less than 50%.
“There is a difference in the CoronaVac vaccine for the influenza vaccine: since the influenza vaccine is made with the viruses that circulated the most in the previous winter in the southern hemisphere here in Brazil, sometimes there is a mismatch between the strains. So the effectiveness decreases, this is normal, we measure it after vaccination ”, explains Melissa. Palmieri, director of the São Paulo regional SBIm (Brazilian Society of Immunizations).
In the case of the new coronavirus, there are now dozens of variants, but all of one strain. Therefore, vaccines already produced confer immunity against any existing form of SARS-CoV-2.
Also, science is still working to improve immunization. Because we do not have mass vaccination yet, the points about whether transmission will be reduced by vaccination with current immunizers will still be clarified.
“We have more effective vaccines, less effective. But it is factors such as strategy, target audience and the number of people to be vaccinated that will put the result into practice. Only effectiveness is not a parameter,” adds the SBIm specialist.
Tuberculosis is a serious disease controlled by vaccination.
Like CoronaVac, other immunizers in the country do not eliminate the disease, but prevent its serious forms, such as the bacillus that causes tuberculosis.
As each infectious agent has its own behavior, each vaccine has its technology and way of acting. Efficiency is considered a prerequisite. For example: to be approved by Anvisa, a vaccine against the new coronavirus would have to reach at least 50%.
“The tuberculosis vaccine is not very effective, it is 60% for the classic pulmonary form. But it prevents serious forms of the disease. It is a way of working to reduce the impact of the disease ”, explains the epidemiologist, professor. and the researcher Ana Brito, from Fiocruz (Fundação Oswaldo Cruz) and UPE (University of Pernambuco).
The tuberculosis vaccine prevents serious forms such as tuberculous meningitis and miliary tuberculosis (which spreads throughout the body). It must be given to babies and it is free. In the case of CoronaVac, the effectiveness against the severe form of covid-19 was 100%, according to the São Paulo government.
Some immunizers are able to prevent the disease. “This is the case of vaccines against measles or rubella, for example, which are capable of preventing the disease by producing a swimming pool immunity. And in theory, the protection against the disease is more durable and can even be permanent, ”he says.
