That the efficiency of vaccines against covid-19 decreases over time, it was already known. Now a study published by Science indicates that the protection of preparations against infection from Janssen, Moderna and Pfizer fell on average, from 87.9% to 48.1% in eight months , with the Janssen vaccine losing the most , until staying with an efficacy of 13.1% against the coronavirus.
Research conducted with 780,000 people in the United States indicates that the greatest loss of efficiency was for Janssen (Johnson & Johnson), whose protection against infection fell from 86.4% in March to 13.1% in September of this year.
The preparation that endured the most was that of Moderna with a decrease from 89.2% to 58%, while Pfizer/BioNTech went from 86.9% to 43.3%, between February and October 1 last.
The study, according to its authors, is the first to compare the declining protection rates of available vaccines for most Americans and to report mortality rates after infection.
The research – signed by the Institute of Public Health, the Veterans Affairs Medical Center and the University of Texas Health Sciences Center, all of them Americans – analyzed the covid-19 infection according to the vaccination of 780,225 veterans.
The study period coincides with the appearance and predominance of the Delta variantin the United States and patterns of infection progression over time were consistent by age, regardless of vaccine eligibility, implying that Delta is the main determinant of infection, the experts add.
Protection against death by Covid
In addition, they highlight that vaccination with any of the three preparations protected people who became infected against death.
The relative benefit of vaccines for protection against death was greatest for people younger than 65 years, but was also “very strong” for those older than that age.
The study showed that the risk of death from covid-19 was higher in unvaccinated veterans, regardless of age and comorbidities.
By age, in the case of those under 65 years of age, the vaccines were, on average, 81.7% effective against death: Pfizer 84.3%, Moderna 81.5% and Janssen 73%, according to data from July to October.
Among people aged 65 or older, the overall efficacy against death was 71.6%. Modern 75.5%; Pfizer 70.1% and Janssen 52.2%.
This research offers “a solid basis to compare the long-term efficacy of vaccines against covid-19 and a lens to make informed decisions” about primary vaccination, booster doses or measures such as the use of the mask, according to the Lead study author Barbara Cohn of the US Institute of Public Health.