COVID-19 vaccine reduces severity, length, viral load for those who still get infected

According to ongoing research by the University of Arizona Health Sciences, individuals who contract COVID-19 after vaccination have a lower viral load and experience shorter incubation times. They also have milder symptoms.Jeff Burgess, MD, MS, MPH, associate professor at the Mel and Enid Zuckerman College of Public Health and principal investigator of Arizona Healthcare, Emergency Response and Other Essential Workers Surveillance, (AZ HEROES), said that COVID-19 is unlikely to occur if you are vaccinated. Even if you get it, you will have less virus in your body and your illness will likely be milder.The COVID-19 vaccines have been proven to be very effective in preventing COVID-19 infections. However, there are still some breakthrough infections. SARS-CoV-2 was identified in 5 of the 3,975 participants in 2 studies. There were 11 partially vaccinated participants and 156 unvaccinated. About half of the participants came from Arizona.Research showed that participants who had received the Moderna and Pfizer messenger RNA vaccines were 40% less likely to contract the virus than those who hadn't been vaccinated. Although viral load, which is the amount of SARS-2 virus in a sample of blood tested in a study participant's body, is not a measure of contagiousness but early COVID-19 research indicates that viral load may play an important role in secondary transmission and disease severity.Researchers also looked at the length of time before determining disease severity. Unvaccinated people had more infections than vaccinated ones. The majority were found for at least two weeks. This represents a 66% decrease in the likelihood that an unvaccinated participant will be diagnosed with an infection lasting more than one week.The risk of developing COVID-19 and associated fevers was 58% lower in vaccinated individuals. They reported being sick for an average of two days less than unvaccinated, with an average of six days less illness.The New England Journal of Medicine published data from two ongoing CDC funded studies, the AZ HEROES and the Abt Associates Research on the Epidemiology of SARS-2 in Essential Response Personnel (RECOVER). Participants in the study - first responders and health care workers, as well other critical and frontline workers, from eight U.S. states - continue to have weekly nasal swabs for COVID-19 testing, as well quarterly blood tests.Researchers analyzed data from Dec. 14 through April 10 and found that two doses mRNA COVID-19 vaccine were 91% efficacious against infection by SARS-CoV-2. This virus causes COVID-19. The report also indicated that a single dose vaccine was 81% effective against SARS-2 infection. This data is in line with the U.S. Centers for Disease Control and Prevention's Morbidity and Death Weekly Report, March 29.Dr. Burgess stated that "we are still seeing high levels of vaccine efficacy, so we feel good." "But, more importantly, we have added measures of the severity and duration of infection in individuals who have been vaccinated to compare with those who have not. We also measured how many viruses there were and how long they lasted."AZ HEROES researchers continue to research COVID-19 immunity, vaccine efficacy, and are now beginning to study the frequency of SARS CoV-2 variants. Original funding for the study came from a $7.7million CDC grant.Karen Lutrick (AZ HEROES research group member), assistant professor in Family and Community Medicine at College of Medicine – Tucson, said, "We were recently awarded another year of financing." "We are grateful for the contributions of all our AZ HEROES, RECOVER, and other participants. Without them, we wouldn’t be able to share this information.###Janko Nikolich?ugich, MD and PhD, is the head of the College of Medicine – Tucson's Department of Immunobiology. She also codirects the Center on Aging. Kate Ellingson and Joe Gerald, MD and PhD, are other members of the AZ HEROES Research Team.AZ HEROES is still looking for participants. This includes health care workers, first response personnel, and other essential workers such as teachers, food service workers, and student workers who haven't been vaccinated. Both those with and without a history of COVID-19 are encouraged to apply.