The effectiveness of Pfizer and ModernA RNA vaccines against COVID-19 fell from 91 percent to 66 percent after the “delta” -variant became dominant. This is reported in a press release on MedicalXpress.
US Disease Control and Prevention Centers (CDC) began to study the real efficiency of two RNA vaccines since their first approval among medical personnel, emergency response services and other health workers. Volunteers from six states passed testing every week, as well as when the symptoms of COVID-19 appear. This allowed researchers to estimate the effectiveness of vaccines against symptomatic and asymptomatic infection.
The effectiveness of the vaccine was estimated at 91 percent in the initial period of the study from December 14, 2020 to April 10, 2021. But for a few weeks, when the ultraconactagious “delta” -variant became dominant, efficiency fell to 66 percent. The results disclose a moderate decrease in the effectiveness of vaccine against COVID-19 in preventing infection, but a steady reduction in the risk of infection by two-thirds emphasizes the unchanged importance and advantages of vaccination against COVID-19.
According to a recent study of patients in New York, conducted by CDC, protection against severe diseases seems more stable and exceeds 90 percent. Another study showed that unvaccinated people are 29.2 times more often hospitalized with COVID-19 than vaccinated, which corresponds to about 97 percent effectiveness.