Participant Information

What is the purpose of this study?

Some people noted experiencing unexpected changes in their menstrual cycle, including spotting and heavier cycles, following vaccination. The purpose of this study is to examine the effect of the COVID-19 vaccine on the menstrual cycle.

The study does not provide the vaccine, and study team members will not be offering guidance as to whether or not one should receive a COVID-19 vaccine. We are interested in recruiting participants who menstruate and are willing to receive the vaccine for the first time.

What is known about the effect of COVID-19 vaccine on the menstrual cycle?

The initial COVID-19 clinical trials for the Pfizer, Moderna, and Johnson and Johnson vaccines did not study the effect of COVID-19 on the menstrual cycle and health. Some people reported a change in their typical menstrual cycle following vaccination. However, no data, to our knowledge, has been collected prospectively.

Where can I go for more information about the COVID-19 vaccine?

What does the study involve?

This study is done completely virtually, and we are recruiting participants from the United States. This study will involve recording 1 menstrual cycle prior to taking the COVID-19 vaccine and 2-3 cycles after receiving the vaccine. This will be done using a simple and validated menstrual diary where one records how many pads and/or tampons used every day or the volume of blood collected in a marked menstrual cup. This information will be collected using a survey that is sent everyday via text message. Filling the daily survey will take 1-2 minutes.

The total study duration is about 100 days. Participants will be compensated with $75 after study completion.

What are the eligibility criteria?

  • Age between 18 and 55
  • Have had at least one menstrual cycle in the past 12 months
  • English-speaking
  • Intention to get a COVID-19 vaccine in the near future.

Can I participate if I had COVID-19 already?


Can I participate if I have already received the COVID-19 vaccine?

Yes, you can participate if you will receive the COVID-19 booster dose.

How do I participate?

Fill out a short screening survey (below) to determine if you are eligible to participate in the study. If you are eligible, continue taking the rest of the survey and the daily surveys that will be sent via text. No in-person study visits will be required.

Why are you studying the effect of COVID-19 on the menstrual cycle?

Menstrual health is considered an indicator of general well-being, yet it is understudied. The clinical trials of the Pfizer, Moderna, and Johnson and Johnson vaccines did not check for menstrual irregularities. Thus, little is known about the effect of the COVID-19 vaccine on menstrual health.
The results of this study can offer people who menstruate a better insight into the possible side effects, or lack thereof, of COVID-19 vaccine on the menstrual cycle. This will ultimately reduce vaccine hesitancy among this large population and improve vaccine enrollment rates.

Who is funding this study?

This study is funded by the National Institute of Health (NIH). You can read more about this here.