- Waldman, Sarah E;
- Buehring, Tara;
- Escobar, Daniel J;
- Gohil, Shruti K;
- Gonzales, Ralph;
- Huang, Susan S;
- Olenslager, Keith;
- Prabaker, Kavitha K;
- Sandoval, Tessa;
- Yim, Jennifer;
- Yokoe, Deborah S;
- Cohen, Stuart H
In a retrospective, cohort study at 4 medical centers with high coronavirus disease 2019 vaccination rates, we evaluated breakthrough severe acute respiratory syndrome coronavirus 2 Delta variant infections in vaccinated healthcare workers. Few work-related secondary cases were identified. Breakthrough cases were largely due to unmasked social activities outside of work.