To quantify the impact of children's birthday parties on the transmission of SARS-CoV-2 to grandparents in Denmark.
Approach:
Study Design: A nationwide register-based cohort study was conducted using Denmark's administrative and health registers to link grandparents with their grandchildren and SARS-CoV-2 test results.
Exposure Definition: Children's birthdays were treated as exogenous markers for increased intergenerational contact, with a focus on the 7-day period following the birthday.
Outcome Measurement: The primary outcome was a positive SARS-CoV-2 test result, with secondary outcomes including death within 30 days of a positive test.
Statistical Analysis: Cox proportional hazards regression was used to estimate hazard ratios comparing infection risk during birthday windows versus non-birthday periods.
Key Findings:
Children's birthday parties were associated with increased SARS-CoV-2 infection risk among grandparents.
The study utilized a large dataset from Denmark's COVID-19 surveillance system, ensuring high case ascertainment.
The analysis accounted for different SARS-CoV-2 variants circulating during the study period.
Interpretation:
Limitations:
The study design may not account for all potential confounding factors influencing transmission.
The observational nature of the study limits causal inferences.
