Web and social media searches highlight menstrual irregularities as a global concern in COVID-19 vaccinations.

Delineation of public concerns that prevent vaccine compliance is a major step in generating assurances and enhancing the success of COVID-19 prevention programs. We therefore sought to identify public concerns associated with COVID-19 vaccines, as reflected by web and social media searches, with a focus on menstrual irregularities. We used trajectory analyses of web and social media search data in combination with global COVID-19 data to reveal time-dependent correlations between vaccination rates and the relative volume of vaccine and period related searches. A surge of period and vaccine related Google searches followed the introduction of Covid vaccines around the world, and the commencement of vaccination programs in English speaking countries and across the United States. The relative volume of searches such as "Covid vaccine menstrual irregularities", "Covid vaccine menstrual period", "Pfizer vaccine menstruation", and "Moderna vaccine menstruation" was each significantly correlated with vaccination rates (Spearman r = 0.42-0.88, P = 4.33 × 10-1.55 × 10), and significantly different before and after the introduction of Covid vaccines (Mann-Whitney P = 2.00 × 10-7.10 × 10). TikTok users were more engaged in period problems in 2021 than ever before. International, national, and state-level correlations between COVID-19 vaccinations and online activity demonstrate a global major concern of vaccine-related menstrual irregularities. Whether it is a potential side effect or an unfounded worry, monitoring of web and social media activity could reveal the public perception of COVID-19 prevention efforts, which could then be directly addressed and translated into insightful public health strategies.