Breakthrough COVID-19 may be less infectiousBeing fully vaccinated against COVID-19 significantly decreased the probability of virus culture positivity in breakthrough cases versus cases in unvaccinated healthcare workers, according to a study on the non–peer-reviewed research server, medRxiv.The results, published late last week, showed that 68.6% of 161 COVID-19 breakthrough infections had positive nasopharyngeal swabs compared with 84.9% of infections in unvaccinated patients.
Cycle threshold value (Ct value, an inverse proxy for viral load) was similar for the two groups and decreased throughout the first 3 days of illness in breakthrough cases.