Unexpected vaginal bleeding and COVID-19 vaccination in nonmenstruating women

"Abstract

The association between coronavirus disease 2019 (COVID-19) vaccination and vaginal bleeding among nonmenstruating women is not well studied. The Norwegian Institute of Public Health followed several cohorts throughout the pandemic and early performed a systematic data collection of self-reported unexpected vaginal bleeding in nonmenstruating women. Among 7725 postmenopausal women, 7148 perimenopausal women, and 7052 premenopausal women, 3.3, 14.1, and 13.1% experienced unexpected vaginal bleeding during a period of 8 to 9 months, respectively. In postmenopausal women, the risk of unexpected vaginal bleeding (i.e., postmenopausal bleeding) in the 4 weeks after COVID-19 vaccination was increased two- to threefold, compared to a prevaccination period. The corresponding risk of unexpected vaginal bleeding after vaccination was increased three- to fivefold in both nonmenstruating peri- and premenopausal women. In the premenopausal women, Spikevax was associated with at 32% increased risk as compared to Comirnaty...

Discussion

... Increased risk after both Pfizer and Moderna suggest a mechanism related to the spike protein and not to other vaccine components... An increased risk of PMB [postmenopausal bleeding] diagnosis after SARS-CoV-2 infection has also been described, further supporting a role of the viral agent. Pathways related to local changes in the endometrium, possibly resulting from a spike related immune response or related to the endometrial expression of ACE2 receptors may be involved."