Like all medicines, vaccines can cause side effects. Covid vaccines tap into our immune system’s natural response to an infection, which can make us feel temporarily unwell.

Most vaccine side effects are mild and short-term, and not everyone gets them.

  • Having a painful arm where you had your injection. This tends to be worst around 1-2 days after the vaccine
  • Feeling tired
  • Headache
  • General aches, or mild flu-like symptoms

There is no evidence to suggest that the Covid vaccines affect fertility.

Pregnant women were not routinely advised to have the vaccine because pregnant people were excluded from the Covid vaccine trials. Even though participants were asked to avoid becoming pregnant, 57 pregnancies occurred across the trials of the three vaccines approved for use in the UK according to Nature Reviews Immunology.

In Britain, the JCVI has now said pregnant women should get a Covid-19 vaccine made by Pfizer/BioNTech or Moderna because there is more real-world data to show they are safe.


The MHRA is carrying out a detailed review of reports of a blood clotting problem affecting a small number of people who have had the Oxford/AstraZeneca vaccine.

Although the risk of blood clotting after vaccination remains extremely rare, it is now advised for healthy under 40s to be offered an alternative to the Oxford/AstraZeneca vaccine.

If you are over 40 or have other health conditions, the benefits of being vaccinated outweigh any potential risk.


This content has been reviewed by clinicians and public health professionals Page last reviewed: 23 April, 2021