The companies Pfizer e BioNTech announced on Thursday (1st) that the vaccine they developed against Covid-19 managed to prevent all symptomatic cases of the disease caused by the South African variant of the coronavirus, B.1.351. It is the first result of its kind to be released against this variant.
The data, which have not yet been published in a scientific journal, are part of the vaccine efficacy results after 6 months of application, announced this Thursday by the companies. The findings showed that the vaccine remained effective.
The vaccine was applied in 46,307 volunteers in the United States and South Africa in the phase 3 tests. More than 12,000 of them were followed up in that period after the second dose.
Of the total volunteers, 800 were from South Africa. In this part of the tests, 9 cases of Covid-19 were seen, all in the placebo group. Hence the 100% effectiveness was calculated against variant B.1.351, which is prevalent in the country, indicated the scientists.
In the evaluation of microbiologist Natália Pasternak, the numbers used by scientists to determine 100% effectiveness are low.
“The numbers are small for an analysis of effectiveness, but considering that they are confirmatory of previous robust analyzes, it is a great sign that the [vacina da] Pfizer works well for the South African variant “, says Pasternak, who is president of the Instituto Questão de Ciência.
“And remembering that previous immunogenicity studies [criação de anticorpos] indicated loss of neutralization, but neutralizing antibodies are not the only immune response “, he points out.
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- There were 927 cases of Covid-19 with symptoms (symptomatic) in both countries. Of these, 850 were in the placebo group (who did not receive the vaccine) and the other 77, in the group that received the vaccine. With these data, scientists calculated an efficiency of 91.3%. The percentage is slightly lower than what had been seen in preliminary vaccine efficacy studies, published in December in a scientific journal, but it is still considered high.
- Of the 927 cases of the disease, 697 were observed in USA. Of these 697, 647 occurred in the placebo group; the other 50 were in the vaccine group. With these data, the calculated effectiveness was 92.6%.
- According to the criteria of the United States Disease Control Center (CDC), no one who received the vaccine had a serious case of Covid-19. All 32 cases considered severe in the USA were in the placebo group. In the CDC analysis, the vaccine was 100% effective against severe cases.
- On the other hand, an analysis by the Food and Drug Administration (FDA), a species of American Anvisa, considered that there were 22 serious cases of Covid in the USA. Of these, 21 were in the placebo group and 1 in the vaccine group. Under the FDA’s criteria, therefore, the vaccine was 95.3% effective against severe cases.
- The effectiveness was, in general, consistent between demographic data of age, sex, skin color and ethnicity and among participants who had comorbidities.
- The researchers analyzed the samples in which the coronavirus was detected. Of the 9 cases of Covid in South Africa, 6 were caused by B.1351.
- No serious security concerns was observed in the trial participants.
Palestinian Muslim cleric receives dose of vaccine against Covid-19 from Pfizer in Ramallah, in photo of March 21 – Photo: AP Photo / Nasser Nasser
The data supports previous results from laboratory studies showing that the vaccine induced a robust neutralizing antibody response for variant B.1.351. Research had shown that the amount of antibodies generated against this variant was less than that seen in relation to the “original” virus. Scientists had estimated that this drop, however, would not affect the vaccine’s effectiveness, which was confirmed with the new data.
Pfizer and BioNTech said they plan to send detailed data for scientific review by other scientists and possible publication in “the near future”.
- Butantan investigates whether a South African-like coronavirus variant identified in the interior of SP could be an evolution of P.1
The immunizer has been approved for use and is being applied in the United States, United Kingdom, European Union and Israel, among other countries.
Efficacy in adolescents
On Wednesday (31), Pfizer and BioNTech had announced that their vaccine has also shown 100% effectiveness in adolescents aged 12 to 15 years. The immunizer was already authorized to be applied to young people from 16 years old.
The study was carried out with 2,260 adolescents aged 12 to 15 years in the United States. In the trial, 18 cases of Covid-19 were observed in the placebo group versus none in the vaccinated group. According to the companies, the results showed a strong creation of antibodies in a subset of adolescents one month after the application of the second dose.
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