For example, as of mid-September, 41 out of 49 patients hospitalized with COVID-19 at UC Davis Medical Center in Sacramento were unvaccinated.īreakthrough infections where vaccinated people do become sick can occur, especially in areas where virus prevalence is high.Īlthough vaccinated people with a breakthrough infection are much less likely to become severely ill than unvaccinated, the new study shows that they can be carrying similar amounts of virus and could potentially spread the virus to other people. Vaccines have been shown to be highly effective in preventing severe disease, hospitalization and death from COVID-19. There was no significant difference in viral load between vaccinated and unvaccinated, or between asymptomatic and symptomatic groups. When they analyzed the data, the researchers found wide variations in viral load within both vaccinated and unvaccinated groups, but not between them. Just over half (198) of the Unidos en Salud samples were unvaccinated. The Unidos en Salud samples included both asymptomatic and symptomatic cases. All the Healthy Yolo Together samples were from people who were asymptomatic at the time of positive test result, and three-quarters were from unvaccinated individuals. The researchers looked at 869 positive samples, 500 from Healthy Yolo Together and 369 from Unidos en Salud. The study was conducted with positive samples from asymptomatic testing at UC Davis for Healthy Yolo Together and at the Unidos en Salud walk-up testing site in the Mission District of San Francisco. “Our study adds to existing data about levels of virus in vaccine breakthroughs in two settings of high ongoing community prevalence of the delta variant,” said Professor Richard Michelmore, director of the UC Davis Genome Center. The study is currently available online as a preprint from MedRxiv. The findings underscore the continuing need for masking and regular testing alongside vaccination, especially in areas of high prevalence, the authors wrote. It also found no significant difference between infected people with or without symptoms. Robert Arneson: Serious Ideas Behind that HumorĪ new study from the University of California, Davis, Genome Center, UC San Francisco and the Chan Zuckerberg Biohub shows no significant difference in viral load between vaccinated and unvaccinated people who tested positive for the delta variant of SARS-CoV-2.Graduate School of Management Events Calendar.College of Letters and Science Events Calendar.College of Biological Sciences Events Calendar.College of Agricultural and Environmental Studies.Commencement Schedule and Graduation Celebrations.Building Community to Benefit Physics Students.Battling Barriers, Bias to Retain and Recruit STEM Talent.College of Agricultural and Environmental Science.International Exam and Visa Requirements.