(CNN) — Even if they do contract a post-vaccination infection, vaccinated people don’t get as seriously ill from COVID-19, two different teams of researchers reported Thursday.
Both studies show that vaccines strongly protect against severe illness and death, even months after people were first vaccinated and while the more transmissible delta variant renewed the spread of the virus.
A large ongoing study of 780,000 veterans shows that all three vaccines used in the US provide strong protection against death from COVID-19, even as their efficacy against mild, asymptomatic infections has been drastically reduced.
Researchers who looked at men and women receiving treatment at Veterans Health Administration facilities found that the overall efficacy of the vaccine against all types of infection dropped from 87.9% in February to 48.1% in October. They only counted fully vaccinated veterans and only counted the results of polymerase chain reaction (PCR) tests, the gold standard for determining infection.
“Although the progression of infection increased the risk of death, vaccination continued to protect against death in people who became infected during the sudden delta outbreak,” the researchers wrote in their report, published in the journal Science.
“Our analysis by vaccine type, including the Pfizer-BioNTech, Moderna, and (Johnson & Johnson de) Janssen vaccines, suggests a decrease in vaccine effectiveness against infection over time, particularly for the Janssen vaccine. However, Despite the increased risk of infection due to the delta variant, vaccine efficacy against death remained high and, compared to unvaccinated veterans, those who were fully vaccinated had a much lower risk of death after vaccination. These results demonstrate an urgent need to restore multiple layers of protection, such as the use of masks and physical distancing, even among vaccinated people, while strengthening current efforts to increase vaccination. “
The researchers say their data is more up-to-date than data provided by the U.S. Centers for Disease Control and Prevention (CDC), although it only refers to veterans, who may not be representative of the population of The US study group represents 2.7% of the US population and although it leans more in favor of men, it may represent more minorities than other study groups, Barbara Cohn, an epidemiologist, told CNN. from the Oakland Institute of Public Health, California, who helped conduct the study.
In March, the Johnson & Johnson vaccine was 86.4% effective in preventing any type of infection. By September, this had fallen to 13%, they reported.
In March, Moderna’s vaccine was 89.2% effective in preventing any infection. This fell to 58% in September.
Pfizer’s vaccine was 86.9% effective against any infection in March and effectiveness fell to 43.3% in September, they reported.
From July to October 2021, they found that the effectiveness of the death vaccine among veterans under 65 was 73% for J & J’s Janssen vaccine, 81.5% for Moderna’s, and 84.3% for Pfizer and for those over 65 it was 52.2% for Janssen, 75.5% for Moderna and 70.1% for Pfizer.
“Everyone does better if they are vaccinated, including people from Janssen,” Cohn said. “Vaccination keeps people out of the hospital, even during delta.”
A second study was coordinated with the CDC and found that people vaccinated with the Pfizer or Moderna vaccines are much less likely to end up in the hospital on a ventilator or die from an infection than unvaccinated people.
Unvaccinated patients accounted for 91% of COVID-19 deaths and nearly 94% of those with a combined need for respirators or death, the team reported in the report. Journal of the American Medical Association.
“Now we are very confident that the vaccine is still helping you, even if you do get COVID,” Dr. Wesley Self, an associate professor at Vanderbilt University who led the study team, told CNN. “Even those who do get sick don’t get as sick as they would if they weren’t vaccinated.”
The team of 21 US hospitals in 18 states examined 4,513 patients hospitalized for respiratory illnesses between March and July. “Unvaccinated patients accounted for 84.2% of COVID-19 hospitalizations. COVID-19 hospitalization was significantly associated with a lower likelihood of vaccination,” the team wrote.
Not enough people had been vaccinated with Johnson & Johnson’s Janssen vaccine to provide enough data for the study, Self said. He noted that other studies have shown that the Janssen vaccine is less effective than the mRNA vaccines made by Pfizer and Moderna.
“We have known for several months that mRNA vaccines prevent people from becoming infected with covid and prevent people from being hospitalized with covid. What was not clear from the previous data was whether people still get covid despite being vaccinated. Is the vaccine beneficial? The answer is a resounding yes, “said Self.
“They are much less likely to become seriously ill and die. That tells us that vaccines are reducing the severity of the disease.”
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