In the first direct comparison of the effectiveness of Vaccines against COVID-19 of Pfizer-Biontech and modern, a group of researchers has examined the electronic clinical histories of American veterans who had received each of them.
Both were very effective in preventing the results of COVID-19, such as documented infection, hospitalization and death. However, it was discovered that the modern vaccine offered a higher level of protection, including 21% less risk of documented infection and 41% less risk of hospitalization, as they publish in the magazine 'New England Journal of Medicine'.
"Both vaccines are incredibly effective, with only rare cases of rupture," says Dr. JP houses, a member of the research team formed by experts from the United States Department of Veterans Affairs (VA), Harvard School of Public Health. and the Hospital Brigham and Women's-. But regardless of the predominant strain -Alfa before and delta after-, modern proved to be slightly more effective. "
The researchers designed their study of comparative efficacy to address the issue, until now without response, from which of the two mRNA vaccines is more effective. Efficiency was measured in terms of five results related to COVID: Covid-19 documented, symptomatic disease, hospitalization, entry into the UCI and death. The researchers were based on the electronic clinical histories of US veterans who received one of the two Vaccines against COVID-19 between the beginning of January 2021 and mid-May 2021.
As it was initially designed, the research focused on the alpha variant that predominated at that time. The study matched 219,842 receptors from the Pfizer vaccine with the same number of receptors from the modern vaccine. The two groups were paired depending on a series of clinical and demographic factors that could affect the results.
During the 24-week follow-up period, the estimated risk of documented infection was 4,52 events per 1,000 people in the group of modern vaccine and 5.75 per 1,000 in the Pfizer group. This represents an excess of 1.23 cases of infection documented per 1,000 people in the Pfizer group. The researchers also observed an excess of symptomatic Covid-19 (0.44 events), hospitalization (0.55 events), entry into the ICU (0.10 events) and death (0.02 events) for every 1,000 people in the Group of Pfizer in relation to the group of modern, but these differences were minor.
This pattern of lower risk for modern was maintained at an additional phase of research that covered a temporary frame with delta as main strain. In this comparison, the excess risk of infection documented for 12 weeks was 6.54 events per 1,000 people for the Pfizer vaccine, compared to modern. Given the shortest time available for this complementary research, the infection was the only result that the researchers analyzed. In addition, the estimates were considered less accurate because a smaller number of individuals were eligible for this analysis.
Randomized trials comparing mRNA vaccines with placebos had previously shown that both vaccines were very effective against symptomatic infection by Covid-19 (95% efficiency for Pfizer-Biontech, 94% for modern), and similar benefits were observed in The use of the vaccine in the real world.
"Given the high efficiency of modern and Pfizer vaccines, confirmed by our study, any of them is recommended to anyone who is offered by the possibility of choosing between the two," said the first author of the study, Dr. Barbra A. DICKERMAN, Epidemiology Instructor of Public Health School th Chan of Harvard--. However, although the estimated efficacy differences were small on an absolute scale, they can be significant if the large population scale is taken into account that these vaccines apply. This information may be useful for the broader decision-making bodies. "
The extensive system of VA records, which covers millions of patients throughout the country, allowed a very large sample size. This, in turn, allowed the study to identify even small differences in efficiency between the Vaccines of Pfizer and modern. The researchers used a methodology known as causal inference to reflect as faithfully a randomized assay, the gold standard in health research. The causal inference is a type of data analysis that helps researchers draw firm conclusions about the cause and effect.
Among the experts in the causal inference of the research team are Dickerman and Dr. Miguel A. Hernán, professor of bioestatistics and epidemiology of the Harvard School of Health and Director of the Causal Laboratory of the School. DICKERMAN, Hernán and Casas Cóligen The Nucleus of Va-causal methods, an association between VA and Harvard focused on the development of new methods of causal inference in research.
One of the main challenges of this research was to ensure that the groups of vaccines under study were comparable with respect to attributes, other than the vaccine received, which could predict the infection or severity of the disease. The VA databases allowed researchers to accurately characterize the recipients of each type of vaccine and match them closely in age, sex, race, geographical location and other attributes that could affect the results related to the COVID-19 .
Date Of Update: 08 December 2021, 11:02
