Two-Year-Span Breast Cancer Screening Uptake in Japan after the COVID-19 Pandemic and Its Association with the COVID-19 Vaccination.

There is limited information on whether the COVID-19 pandemic was associated with decreased breast cancer screening uptake and if COVID-19 vaccination was associated with an increase in screening uptake. Our study explored the uptake of breast cancer screening in Japan after the COVID-19 pandemic and assessed its association with the COVID-19 vaccination. We analyzed data from the Japan COVID-19 and Society Internet Survey (JACSIS), a web-based prospective cohort survey, and we included 6110 women without cancer history who were aged 40 to 74 years that participated in the 2012 and 2022 surveys. We examined the regular breast cancer screening uptake before and after the pandemic and employed a multivariable Poisson regression model to seek any association between COVID-19 vaccination and screening uptake. Of 6110, 38.2% regularly participated in screening before the pandemic and 46.9% did so after the pandemic. Individuals unvaccinated due to health reasons (incidence rate ratio (IRR) = 0.47, 95% CI: 0.29-0.77, = 0.003) and for other reasons (IRR = 0.73, 95% CI: 0.62-0.86, < 0.001) were less likely to undergo screening compared to fully vaccinated individuals. There was no long-term decrease in breast cancer screening uptake after the pandemic in Japan. Vaccination was linked to increased uptake, but there was no dose relationship.