According to the Heroes-Recover study funded by the US CDC, the mRNA vaccines Pfizer-BioNTech and Moderna reduce the risk of infection with the coronavirus SARS-COV-2 by 91% in fully vaccinated people. This study also shows that mRNA vaccination makes symptoms milder and shorter for the few vaccinated people who contract COVID-19. The study also suggests that people who are vaccinated but infected are less likely to transmit the virus than those who are not.
The first results of the HEROES-RECOVER study led by Arizona State University were published last March. They were enriched with 4 additional weeks of data and confirm the first trends observed.
In the new analysis, 3,975 participants, mostly caregivers or workers more likely to be exposed to the virus because of their occupation, tested weekly for SARS-CoV-2 for 17 consecutive weeks (from December 13, 2020 to December 10, 2020). April 2021) at eight US sites. The participants themselves collected nasal swabs that were lab tested for SARS-CoV-2. If the tests were positive, the samples were subjected to further testing to determine the amount of virus detectable in the nose and the number of days the tests came back positive.
Participants were followed over time and data was analyzed according to vaccination status. To assess the vaccine’s benefits, the study researchers took into account the circulation of SARS-CoV-2 viruses in the region and the frequency of use of personal protective equipment (PPE).
After a full vaccination (14 days or more after the second dose), participants’ risk of infection was reduced by 91%. After partial vaccination (14 days or more after dose 1 to 13 days after dose 2), participants’ risk of infection was reduced by 81%. These estimates include symptomatic and asymptomatic infections.
Another lesson is that fully or partially vaccinated people who developed COVID-19 spent an average of six days less being sick and two days less being bedridden. They also had an approximately 60% reduced risk of developing symptoms, such as fever or chills, compared to unvaccinated people. Some study participants infected with SARS-CoV-2 did not develop symptoms.
Other study results suggest that fully or partially vaccinated people who have contracted COVID-19 may be less likely to pass the virus to others. For example, vaccinated and infected people had 40% less detectable virus in their nose and therefore a lower viral load, and the virus was detected for six days less compared to unvaccinated people during infection.
In addition, partially or fully vaccinated people were 66% less likely to be infected with the SARS-CoV-2 virus for more than a week compared to unvaccinated people. While these indicators are not a direct measure of a person’s ability to spread the virus, they have been correlated with a reduction in the spread of other viruses, such as chickenpox and the flu.
https://azheroes.arizona.edu/
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