No causal link between Covid-19 vaccines and menstrual disorders has been found so far, Europe's drugs regulator said on Friday, separately recommending that three new conditions be added as possible side-effects of J&J's coronavirus shot.

The European Medicines Agency said its safety committee had studied cases of menstrual disorders reported after vaccination, adding it had requested more data from vaccine developers to assess the issue.

Menstrual disorders can occur for various reasons, from stress and tiredness to underlying medical conditions such as fibroids and endometriosis.

Separately, the EMA on Friday recommended that immune thrombocytopenia, or low blood platelets, dizziness, and tinnitus, or ringing in the ear, be added to the labels of J&J's single-shot vaccine as potential adverse reactions.

The EU agency stressed that benefits of J&J's vaccine still outweighed any risks, adding that it had analysed 1,183 cases of dizziness and more than 100 cases of tinnitus to reach its conclusion.