Milder and potentially less transmissible COVID-19 in other people inflamed with a Delta or Omicron variant within about five months after their timing or third dose of an mRNA vaccine, according to a prospective surveillance study of the regimen.
Among more than 1100 frontline workers and essential workers, those who received a momentary dose of mRNA vaccine in the 14 to 149 days prior to progression of Delta variant infection had a particularly lower risk of experiencing symptoms than unvaccinated Americans (77. 8% vs. 96. 1%; OR 0. 13, 95% CI 0. 0-0. 6), reported Ashley Fowlkes, ScD, MPH, of CDC in Atlanta, and colleagues in the HEROES-RECOVER network.
Receiving a third dose (booster) within 7 to 149 days prior to Delta infection was associated with an average of approximately 6 fewer symptomatic days (10. 2 vs. 16. 4 days) and a 93% decrease in the likelihood of fever or chills (38. 5% vs. 84. 9%), either statistically significant benefits over non-vaccination, the authors wrote in JAMA.
For Omicron infections, a third dose of vaccine 7 to 149 days before infection was associated with an increased likelihood of symptomatic infection compared with unvaccinated Americans (88. 4% vs. 79. 4%; OR 2. 0, 95% CI 1. 1-3. 5), a According to the researchers, the “unexpected” location is difficult to interpret due to the inability to adapt to some potential confounders.
Despite this, for other people with symptomatic cases of Omicron, a booster dose 7 to 149 days before infection was associated with a decreased risk of fever or chills (OR 0. 25, 95% CI 0. 1 to 0. 5) or seeking medical attention (OR 0. 45, 95% CI 0. 2-0. 9) compared with no vaccination.
“Only participants with advanced infection after the third dose showed consistent symptoms of COVID-19 vaccine attenuation,” Fowlkes and his coauthors noted. “It is conceivable that the memory of immune reminiscence that reduces viral replication and accelerates the elimination of virus-infected cells that would possibly underlie vaccine disease attenuation would possibly be minimized over time. “
Those who received a momentary dose of the vaccine 14 to 149 days before infection with a variant of Delta or Omicron had a lower viral average on quantitative RT-PCR tests compared to the unvaccinated.
Vaccination was also connected to decrease viral viability in any of the teams with this measure: delta variant infections and Americans not vaccinated with the original virus. vaccine at least 150 days before a recurrent infection (4. 1 UFP/mL) or 3rd dose in the 7 to 149 days prior to a recurrent infection (3. 1 UFP/mL), compared with the unvaccinated organization (4. 8 UFP/mL).
“Although viral RNA loss cannot be directly attributed to transmission, the relatively high viral load of Omicron infections, as well as the higher frequency of asymptomatic infections, help previous studies suggesting an arrangement with higher transmission, i. e. , the first 3 to 5 days when infection is viral. “The charge peaked,” the researchers note.
For unvaccinated people, Omicron infections were 5. 6 times (95% CI 1. 6-19. 6) more likely to be asymptomatic than Delta infections.
“This study is consistent with other studies showing that COVID-19 vaccines work,” said John P. Cooke, MD, PhD, of the Houston Methodist Academic Institute in Texas, who was not involved in the study. “This study shows that even if you’re infected, you may not be in as poor health as those who haven’t been vaccinated. “
Previous studies have had combined effects on symptom relief, symptom duration and viral RNA loss with COVID-19 vaccines, Fowlkes’ organization noted. He may be at fault, the authors suggested.
For this study, Fowlkes and colleagues tested the knowledge of 1,199 essential and frontline personnel who showed SARS-CoV-2 infection in six states (Arizona, Minnesota, Texas, Florida, Oregon, and Utah) since December 14, 2020. until 19 April 2022. The follow-up was extended until 9 May 2022. Those included were part of the HEROES-RECOVER network paintings of first responders, physical care personnel and teachers, as well as others who paint at least 20 hours per week. in a task that takes them within 3 feet of others.
For their initial vaccination, 62% won Pfizer-BioNTech and 37% won Moderna, all receiving the same logo for either injection. However, 5. 5% gained another mRNA vaccine logo for the third dose.
The median age was 41 years and 59. 5% of participants were women. Nearly three-quarters were white and 19. 3 percent Hispanic. More than a quarter had at least one chronic illness. At the time of infection, 29% were unvaccinated, 6% had gained their dose at the moment 14 to 149 days earlier, 31% had gained their dose at the moment 150 days or more before infection, and 33% had gained their 3rd dose 7 to 149 days earlier.
Of all infections, 62% were the Omicron variant, 24% were Delta, and 14% were the strain.
Based on clinical experience, “Omicron-related COVID-19 symptoms appeared to be milder and shorter in duration than those of Delta-related COVID-19 across many indicators,” the researchers noted.
Other limitations of the study included the use of self-collected medium peat nasal swabs for virological characteristics research, Omicron virus culture problems for feasibility research, and the small proportion of non-white participants.
Zaina Hamza is editor of MedPage Today and covers gastroenterology and infectious diseases. He’s in Chicago.
This study was supported by CDC’s National Center for Immunization and Respiratory Diseases.
Fowlkes revealed any interest in competition.
Co-authors reported investments and/or relationships with ALSAC, American College of Occupational and Environmental Medicine/Reed, Janssen, Committee on Immunization and Infectious Diseases, National Institute of Allergy and Infectious Diseases, NIH, Novartis, Pfizer, Texas Chapter of the American Academy of Pediatrics, Texas Society of Pediatrics, and Vir Biotechnology.