Boosters not only protect individuals from severe illness, but also reduce the risk of transmission during breakthrough infections, according to a study by researchers at the University of Geneva. The study, published in the journal Nature Medicine, focused on the Omicron subvariant BA.1, which is dominant in many countries, including Germany. The researchers found that boosted individuals were less infectious than unvaccinated individuals during breakthrough infections. The study also showed that the number of infectious virus particles was a more accurate indicator of transmission than the Ct value, which measures the amount of viral genetic material in a sample.
The researchers collected nasal swabs from 565 COVID-19-infected individuals between April 2020 and February 2022, within the first five days of symptom onset. Some participants were unvaccinated, while others had received two doses or a booster. The majority of participants had received mRNA vaccines. The researchers used Ct values and cell cultures to determine the infectiousness of the samples. The study found that double-vaccinated individuals had 80% fewer infectious particles in their upper respiratory tract during Delta infections than unvaccinated individuals. However, there was no difference in infectious particles between unvaccinated and double-vaccinated individuals during Omicron breakthrough infections. Boosters reduced the number of infectious particles by 80%.
The study also found that the number of infectious particles during the Omicron wave was lower than during the Delta wave, despite Omicron’s higher transmissibility. The researchers suggest that this may be due to a different entry mechanism of the virus into cells. The study’s authors emphasize that the results highlight the positive impact of vaccines beyond individual protection from severe illness. Boosters not only protect individuals, but also reduce the risk of transmission during breakthrough infections, making them an important tool in controlling the pandemic.
In conclusion, the study by researchers at the University of Geneva found that boosters reduce the risk of transmission during breakthrough infections, making them an important tool in controlling the pandemic. The study also found that the number of infectious particles during the Omicron wave was lower than during the Delta wave, despite Omicron’s higher transmissibility. The authors emphasize the positive impact of vaccines beyond individual protection from severe illness.
