Viral Load Among Vaccinated and Unvaccinated, Asymptomatic and Symptomatic Persons Infected With the SARS-CoV-2 Delta Variant

We found no significant difference in cycle threshold values between vaccinated and unvaccinated persons infected with severe acute respiratory syndrome coronavirus 2 Delta, overall or stratified by symptoms. Given the substantial proportion of asymptomatic vaccine breakthrough cases with high viral levels, interventions, including masking and testing, should be considered in settings with elevated coronavirus disease 2019 transmission.

Automated summary

There was no significant difference in cycle threshold values between vaccinated and unvaccinated individuals infected with severe acute respiratory syndrome coronavirus 2 Delta, regardless of symptoms. Due to a substantial proportion of asymptomatic vaccine breakthrough cases with high viral levels, interventions such as masking and testing should be considered in settings with elevated coronavirus disease 2019 transmission.