ABSTRACT
Isolation guidelines for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are largely derived from data collected prior to the emergence of the delta variant. We followed a cohort of ambulatory patients with postvaccination breakthrough SARS-CoV-2 infections with longitudinal collection of nasal swabs for SARS-CoV-2 viral load quantification, whole-genome sequencing, and viral culture. All delta variant infections in our cohort were symptomatic, compared with 64% of non-delta variant infections. Symptomatic delta variant breakthrough infections were characterized by higher initial viral load, longer duration of virologic shedding by PCR, greater likelihood of replication-competent virus at early stages of infection, and longer duration of culturable virus compared with non-delta variants. The duration of time since vaccination was also correlated with both duration of PCR positivity and duration of detection of replication-competent virus. Nonetheless, no individuals with symptomatic delta variant infections had replication-competent virus by day 10 after symptom onset or 24 hours after resolution of symptoms. These data support US CDC isolation guidelines as of November 2021, which recommend isolation for 10 days or until symptom resolution and reinforce the importance of prompt testing and isolation among symptomatic individuals with delta breakthrough infections. Additional data are needed to evaluate these relationships among asymptomatic and more severe delta variant breakthrough infections.
Subject(s)
COVID-19 Vaccines/administration & dosage , COVID-19/genetics , COVID-19/metabolism , SARS-CoV-2/physiology , Virus Replication , Virus Shedding/physiology , Adult , COVID-19/prevention & control , Female , Humans , Male , Middle Aged , Time FactorsSubject(s)
HIV Infections/diagnosis , HIV-1 , Biomarkers , Brain/diagnostic imaging , CD4 Lymphocyte Count , Confusion/etiology , Diagnosis, Differential , Female , Fever/etiology , HIV Antibodies/blood , HIV Infections/complications , HIV Infections/virology , HIV-1/immunology , HIV-1/isolation & purification , HIV-2/immunology , Humans , Lymphopenia/etiology , Magnetic Resonance Imaging , Middle Aged , Pharyngitis/etiology , Viral LoadABSTRACT
The impact of coronavirus disease 2019 vaccination on viral characteristics of breakthrough infections is unknown. In this prospective cohort study, incidence of severe acute respiratory syndrome coronavirus 2 infection decreased following vaccination. Although asymptomatic positive tests were observed following vaccination, the higher cycle thresholds, repeat negative tests, and inability to culture virus raise questions about their clinical significance.