It cannot be ruled out that the vaccination has a short-term effect on the strength and regularity of menstruation. So far there have been no studies of this. However, more prolonged negative effects on menstruation are not known, nor are effects on fertility. Nevertheless, there are indications that a COVID-19 vaccination can lead to temporary disruptions to the cycle.
There are many factors that can influence the menstrual cycle. Basically any illness or vaccination can affect it short term. There can also be an effect on the cycle if, for example, the body is under stress.
It is important to point out that reactions such as spotting or post-menopausal bleeding can also be warning symptoms of diseases that need to be investigated and have occurred only coincidentally around the time of the COVID-19 vaccination. In such cases it is essential that patients obtain medical advice.
You can have the vaccination at any point during your menstrual cycle.