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Recent COVID-19 Vaccination and Risk of SARS-CoV-2 Transmission
Sara C Benist1,2, Sarah E Smith-Jeffcoat1, H Keipp Talbot3
1National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia.
JAMA Network Open
|May 15, 2026
Summary
Recent COVID-19 vaccination in a primary case participant reduced SARS-CoV-2 transmission risk within households. This suggests vaccination offers an indirect benefit by decreasing virus spread and overall exposure.
Area of Science:
- Epidemiology
- Infectious Diseases
- Vaccinology
Background:
- COVID-19 vaccine effectiveness (VE) is primarily assessed against severe illness and death.
- Limited data exists on VE in preventing SARS-CoV-2 transmission and infection amidst high population immunity.
Purpose of the Study:
- To estimate COVID-19 VE against SARS-CoV-2 transmission and infection within household settings.
Main Methods:
- A prospective, case-ascertained household transmission cohort study.
- Enrolled primary SARS-CoV-2 cases and their household contacts.
- Verified vaccination status and collected daily nasal swabs for PCR testing.
Main Results:
- Secondary infection risk was 62.4% among household contacts.
- Contacts of primary cases vaccinated ≤6 months prior had reduced infection risk (ARR 0.57).
- No significant difference in infection risk was observed based on household contacts' vaccination status.
Conclusions:
- Recent COVID-19 vaccination in a primary case participant is associated with reduced SARS-CoV-2 transmission.
- COVID-19 vaccination may provide an indirect benefit by lowering transmission and overall exposure.
- Further research is needed to understand long-term VE against infection and transmission.
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