Prior to infection, COVID-19 vaccinations limit spread of Omicron,:esearch

According to a research done in California jails, recent immunisation and boosters lower infectiousness, but the chance of infection is still high. Researchers at UC San Francisco discovered that vaccination and boosting, particularly when recent, helped to stop the spread of COVID-19 in California prisons during the first Omicron wave. The study looked at transmission between persons living in the same cell. Even in circumstances where many individuals are still becoming sick, the study shows the benefits of vaccination and boosters in reducing the transmission. It also shows the cumulative effects of boosting and the extra protection that immunisation provides individuals who have previously developed the illness.

With each extra dose, the chance of transmission decreased by 11 per cent.
“A lot of the benefits of vaccines to reduce infectiousness were from people who had received boosters and people who had been recently vaccinated,” said Nathan Lo, MD, PhD, a faculty research fellow in the Division of HIV, Infectious Diseases and Global Medicine at UCSF and the senior author of the study in Nature Medicine. “Our findings are particularly relevant to improving health for the incarcerated population.”

Data that had been deidentified and gathered by the California Department of Corrections and Rehabilitation was examined by the researchers (CDCR). This includes information for 1,11,687 residents—97% of whom were male—between December 15, 2021, and May 20, 2022, including COVID-19 test results, vaccination status, and housing locations.

Despite the locals’ comparatively high immunisation coverage of 81 percent with the first vaccine series, breakthrough infections were frequent. However, there were not many major illnesses. There were 31 hospitalisations, 22,334 confirmed SARS-CoV-2 Omicron infections, and no COVID-19 deaths in a little more than five months. People who had received vaccinations were substantially less likely to spread breakthrough illnesses than residents who had not: 28% vs 36%.

But for every five weeks that passed since a person received their previous vaccination, the risk of transmission increased by 6%. The chance of spreading the virus was 23% for someone who was reinfected compared to 33% for someone who had never been infected due to natural immunity from a past infection.
Those who had acquired hybrid immunity from both infection and vaccination were 40% less likely to spread the disease. The immunity that one develops from battling infections provided half of the protection, while vaccinations provided the other half.

However, they were taken aback by how quickly the virus spread despite the inhabitants’ relatively high vaccination rates. The researchers stated they were pleased to observe that immunisation gives further protection even for people who have previously been sick.
According to Sophia Tan, a researcher in Lo’s group and the study’s first author, “There is still a significant degree of transmission in our study, regardless of the benefits you observe in vaccine and prior infection.” We believe that these results will help sustain continued efforts to safeguard this vulnerable group.
The prison staff’s vaccination rate should also be raised, as only 73% of them had gotten the primary series at the time of the research. This includes making an attempt to keep residents up to date with booster shots.

Additionally, the overall rate of boosting might be markedly increased. Only 59% of residents and 41% of staff had received all the dosages advised by the U.S. Centers for Disease Control and Prevention (CDC), depending on their age and health condition, at the time of the research.

According to Lo, “people are least contagious two months after immunisation, suggesting that booster shots and widely spread scheduled vaccination programmes may help limit transmission in surges.” Since the danger of infection in this vulnerable group is still so high, new solutions are required.