BACKGROUND

Nursing homes (NHs) were disproportionately affected by the COVID-19 pandemic. However, little is known regarding the kinetics of SARS-CoV-2 shedding in NH residents and staff, which could inform treatment and infection prevention.

METHODS

We enrolled NH residents and staff in eight US states from April to November 2023 and analyzed the kinetics of SARS-CoV-2 using serial antigen and molecular (RT-PCR) tests, whole genome sequencing, and viral culture (VC). Symptoms, vaccination, and treatment were collected via interviews and chart review. Viral load trajectories were modeled with gamma distribution functional forms. Antigen and VC test positivity over time were assessed using a Chi-squared test.

RESULTS

Of the 587 enrolled participants, 86 tested positive and 73 underwent testing for ≥ 10 days; most residents (78%) and staff (87%) had ≥ 3 COVID-19 vaccine doses. The modeled SARS-CoV-2 proliferation period (period prior to reaching peak viral load) had ended for 48% (14/29) of residents and 56% (9/16) of staff when they took the initial RT-PCR test. Both antigen and VC showed higher positivity rates early in the course of disease (Days 0-5 vs. Days ≥ 6) (antigen: p < 0·001, VC: p < 0·001). VC positivity was 15% after Day 5 (14/96); two participants were VC positive after Day 10.

CONCLUSIONS

Peak viral load occurs early in the disease, suggesting asymptomatic and presymptomatic transmission may be a significant driver of transmission. Only two participants had a positive VC after Day 10, supporting current isolation and return to work recommendations.