Second study looked at 43,000 Los Angeles residents 16 years and older. The study found that 25% of all new infections between May and July occurred in fully vaccinated persons, while 71% were among unvaccinated. It was also found that hospitalization rates were significantly lower in fully vaccinated individuals than unvaccinated.
The agency published the studies a week after it released its first three reports about vaccine efficacy, the Delta variant, and breakthrough infections. One of those analyses revealed that vaccine effectiveness among New York adults declined from 91.7 to 79.8 percent in May to late July.
Recent CDC studies have shown that breakthrough infections among vaccinated individuals are still very rare. These studies also support the growing evidence that Covid-19 shot protection decreases over time. Officials at CDC say that booster shots should be administered to Americans eight months after initial vaccination.
Leana Wen, an emergency doctor and professor of public health at George Washington University, stated that the Los Angeles cohort study "tells a compelling story about vaccination's impact in protecting very well against severe diseases and in reducing infections." It also shows why vaccination is important for those who are vaccinated. If others are not vaccinated, the spread of infections among unvaccinated people can increase the risk of developing new infections.
For months, the CDC has been monitoring vaccine efficacy and breakthrough infections in different populations throughout the U.S. The agency has teamed up with a few state health departments to study all cases in fully vaccinated individuals, even those that don't end up in the hospital. It continues to examine vaccine efficacy in groups such as frontline health workers, nursing home residents, and staff.
Officials at the CDC cited recent data from states with breakthrough infections and its New York study as proof that Americans require booster shots. However, critics from the Biden administration as well as outside experts in health have argued that the CDC hasn't presented enough evidence to justify a second round of shots at home when dozens of other countries are still struggling for first doses.
Two officials from the administration claimed that the CDC kept data on vaccine efficacy, breakthrough infections cohorts and other information from senior Biden officials. This has led to questions from the administration regarding the reasons for the recommendation of booster shots.
Some in the White House have been frustrated by the secrecy of the CDC as it analyzed and scrubbed the data. They insist for weeks that breakthrough infections are rare based on the initial spring findings. That was before the Delta virus became the predominant form of coronavirus in America.
Biden repeatedly stressed that Covid-19 is a pandemic of unvaccinated, making speeches as far as late July to claim that "over 99 per cent of Covid-19 deaths were among unvaccinated."
As news of breakthroughs grew and scrutiny intensified health officials clamored for more data about the percentage of serious infections invaccinated Americans.
