Coronavirus vaccines Pfizer-BioNTech and Moderna were 94 percent effective in preventing hospitalizations in fully vaccinated adults aged 65 and over, according to a small study published Wednesday by the Centers for Disease Control and Prevention.
The results, which are in line with clinical trial results, are the first real evidence from the US that the vaccines protect against severe Covid-19. Older adults are at the highest risk of being hospitalized and dying from the disease. More than 573,000 people have died from the virus across the country, according to a New York Times database. As of Tuesday, 141.8 million people had received at least one dose of one of three federally approved vaccines, including about 96.7 million people who were fully vaccinated.
"These results are encouraging and welcome news for two-thirds of people 65 and over who are already fully vaccinated," said Dr. Rochelle Walensky, C.D.C. Director said in a statement. "Covid-19 vaccines are highly effective and these real world results confirm the benefits of clinical trials preventing hospitalizations among the most vulnerable."
The study is based on data from 417 patients enrolled in 24 hospitals in 14 states between January 1 and March 26. About half were 75 years or older.
Both the Pfizer and Moderna vaccines require two shots three to four weeks apart. Older adults who were partially vaccinated – that is, received a dose of the vaccine more than two weeks earlier – were 64 percent less likely to be hospitalized with the coronavirus than unvaccinated seniors, the researchers reported.
The vaccines did not reduce hospitalization rates in people who received their first dose less than two weeks earlier. It takes time for the body to build an effective immune response, and people are considered fully vaccinated two weeks after the last dose in the series.
"This also underscores the persistent risk of serious illness shortly after vaccination, before a protective immune response has been achieved, and reinforces the need for vaccinated adults to continue physical distancing and prevention behaviors," the scientists wrote.