A new CDC study found COVID-19 mRNA vaccines approved by the Food and Drug Administration (Pfizer-BioNTech and Moderna) reduced the risk of infection by 91 percent for fully vaccinated patients. man. This adds to the growing body of real-world evidence of their effectiveness. Importantly, this study was also one of the first to show that mRNA vaccination can benefit people who get COVID-19 even if they are fully vaccinated (14 or more days after dose 2) or partially vaccinated ( 14 or more days after dose 1 to 13 days after dose.2).
“COVID-19 vaccines are a critical tool to overcome this pandemic,” said CDC Director Rochelle P. Walensky, MD, MPH. “Findings from the extended period of time in this study add to the accumulated evidence that COVID-19 mRNA vaccines are effective and should prevent most infections-but that people with completely “vaccinated COVID-19 recipients are more likely to have a slower, shorter illness and are less likely to spread the virus to others. These benefits are another important factor in getting vaccinated.”
The findings come from four weeks of additional data collected in the CDC’s HEROES-RECOVER study of health care workers, first responders, forward workers, and other key workers. . These groups are particularly vulnerable to the virus that causes COVID-19 because of their work. Preliminary results from this study were first announced in March 2021.
In the new analysis, 3,975 participants completed weekly SARS-CoV-2 testing for 17 consecutive weeks (from December 13, 2020 to April 10, 2021) at eight U.S. locations. Participants collected self-administered nasal swabs that were laboratory tested for SARS-CoV-2, which is the virus that causes COVID-19. If the tests returned positive, the specimens were further tested to determine the amount of detectable nasal virus (i.e., viral load) and the number of days the participants tested positive (i.e., viral shedding). ). Participants were followed over time and data were analyzed according to vaccination status. To assess the benefits of the vaccine, the study researchers investigated the circulation of SARS-CoV-2 viruses in the area and how frequently participants used personal protective equipment (PPE) in the workplace and in the community. . Once fully vaccinated, participants ’risk of infection was reduced by 91 percent. After partial vaccination, participants ’risk of infection decreased by 81 percent. These estimates included symptomatic and asymptomatic infections.
To determine if COVID-19 disease was more severe, study participants infected with SARS-CoV-2 were grouped into a group and compared with unattended, infected participants. Numerous studies have shown that those infected after being fully or partially vaccinated are more likely to have a slower and shorter illness compared to those who are not vaccinated. For example, fully or partially vaccinated people who developed COVID-19 spent an average of six fewer days in total sick and two fewer days in bed sick. They also have about 60 percent less risk of developing symptoms, such as fever or chills, compared to those without the vaccine. Some study participants infected with SARS-CoV-2 did not develop symptoms.
Other study findings suggest that fully or partially vaccinated people who get COVID-19 may be less likely to spread the virus to others. For example, fully or partially vaccinated study participants had 40 percent less noticeable virus in their nose (i.e., a small viral load), and the virus was detected in six small days ( ie, viral hemorrhage) compared to those who had not been vaccinated if infected. . In addition, people who were partially or completely vaccinated were 66 percent less likely to test positive for SARS-CoV-2 infection in more than a week compared to those who had not been vaccinated. While these symptoms are not a direct measure of a person’s ability to spread the virus, they are linked to a reduction in the spread of other viruses, such as varicella and influenza.
Overall, the findings of the study support the CDC’s recommendation to be fully vaccinated against COVID-19 as soon as possible. Everyone 12 years and older is now eligible to get the COVID-19 vaccine in the United States. The CDC has several surveillance networks that will continue to examine how COVID-19-approved vaccines work in real-world conditions in different settings and in different groups of people, such as in different groups. of age and people with different health conditions.