COVID-19 Booster Vaccine Shortens Menstrual Cycles in Teens

TOPLINE:

The COVID-19 booster was linked to shorter menstrual cycles in adolescent girls in the 4 months following administration, particularly when teens were in their follicular phase. The vaccine did not appear to be associated with shifts in menstrual flow, pain, or other symptoms.

METHODOLOGY:

• Reports of menstrual cycle changes following the COVID-19 vaccination began to emerge in early 2021, raising concerns about the impact of the vaccine on menstrual health.
• Researchers conducted a prospective study including 65 adolescent girls (mean age, 17.3 years), of whom 47 had received an initial series of COVID-19 vaccination at least 6 months prior to receiving a booster dose (booster group), and 18 had not received the booster vaccine (control group), two of whom had never received any COVID-19 vaccine, four who had received an initial vaccine but not a booster, and 12 who had received an initial vaccine and booster but more than 6 months prior to the study.
• Menstrual cycle length was measured for three cycles prior to and four cycles after vaccination in the booster group and for seven cycles in the control group.
• Menstrual flow, pain, and stress were measured at baseline and monthly for 3 months post vaccination.

TAKEAWAY:

• Participants in the booster group experienced shorter cycles by an average of 5.35 days after receiving the COVID-19 booster vaccine (P = .03), particularly during the second cycle. In contrast, those in the control group did not experience any changes in the menstrual cycle length.
• Receiving the booster dose in the follicular phase was associated with significantly shorter menstrual cycles, compared with pre-booster cycles (P = .0157).
• Menstrual flow, pain, and other symptoms remained unaffected after the COVID-19 booster vaccination.
• Higher stress levels at baseline were also associated with a shorter length of the menstrual cycle (P = .03) in both groups, regardless of the booster vaccination status.

IN PRACTICE:

“These data are potentially important for counseling parents regarding potential vaccine refusal in the future for their teen daughters,” the authors wrote.

SOURCE:

This study was led by Laura A. Payne, PhD, from McLean Hospital in Boston, and was published online in the Journal of Adolescent Health.

LIMITATIONS:

The sample size for the booster and control groups was relatively small and homogeneous. The study did not include the height, weight, birth control use, or other chronic conditions of the participants, which may have influenced the functioning of the menstrual cycle. The control group included a majority of teens who had previously received a vaccine and even a booster, which could have affected results.

DISCLOSURES:

This study was supported by grants from the Eunice Kennedy Shriver National Institute for Child Health and Human Development. Some authors received consulting fees, travel reimbursements, honoraria, research funding, and royalties from Bayer Healthcare, Mahana Therapeutics, Gates, and Merck, among others.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication. A version of this article appeared on Medscape.com.