The government is urging anyone who has had a COVID vaccine to come forward about any side effects even as regulators declared the Oxford/AstraZeneca jab to be safe - here's how you can report any problems.
Speaking at a Downing Street Press conference, Dr June Raine, chief executive of the Medicines and Healthcare products Regulatory Agency (MHRA) said the benefits of getting the COVID vaccine still far outweighed any risks.
Dr Raine said the MHRA has gathered a large amount of data and done significant analysis on the side effects of both vaccines and so far found is "no difference" in the number of blood clots occurring in those who have had the vaccine compared to the general population.
She said while they continued to investigate the issue they advised anyone who suffered a headache that lasts more than four days after the vaccination or bruising beyond the area where the jab was injected to come forward as a precaution.
Watch: PM: Vaccine supply issues will not delay lockdown roadmap
She ended by thanking everyone who had come forward with suspected side effects from the vaccines and said everyone can come forward and report them through the MHRA's Yellow Card system.
What is the Yellow card system?
The Yellow Card scheme run by the MHRA and is the UK system for collecting and monitoring information on safety concerns such as suspected side effects or adverse incidents involving any medicines.
The scheme relies on voluntary reporting of suspected side effects.
Any health professional or member of the public can report suspected side effects through the Yellow Card scheme.
How can I report side effects?
You can report any side effect no matter how big or small through their Yellow Card mobile app or website.
There the first piece of information you will be asked is the vaccine you were given, then you will be asked to fill in all your details and finally a description of any side effects you have received.
How many Yellow cards have been reported about the vaccines?
As of 7 March 2021, 35,325 Yellow Cards have been reported for the Pfizer/BioNTech, 61,304 have been reported for the Oxford University/AstraZeneca vaccine, and 281 have been reported where the brand of the vaccine was not specified.
For both vaccines, the overall reporting rate is around three to six Yellow Cards per 1,000 doses administered.
What have we learned from the Yellow Card reports so far?
The MHRA said data showed that severe allergic reactions to the Pfizer-BioNTech vaccine were very rare (less than one in 10,000 people receiving the jab), with a rate of one to two cases per 100,000 doses administered.
Overall, the MHRA received 101 reports of severe allergic reactions – associated with anaphylaxis or anaphylactoid reactions – for the Pfizer jab, and 13 for the Oxford vaccine. All the people recovered as far as the MHRA was aware.
The regulator said anaphylaxis can be a very rare side-effect to many types of vaccines.
The regulator also received 69 reports of facial paralysis or weakness with the Pfizer-BioNTech vaccine and six for the AstraZeneca jab.
The MHRA makes all information on its findings on side effects available to the public.
Should I worry about large numbers of Yellow card reports?
Not necessarily, it is important to note that Yellow Card data cannot be used to derive side effect rates or compare the safety profile of COVID-19 vaccinations as there can be many factors influencing each report.
First of all this is a voluntary system so some who have side effects will not report them.
Also, as the MHRA wants you to report any negative side effect you feel these could be as small as a minor headache or aches and pains.
The vast majority of reports have been for minor ailments.
Finally, the majority of people who have been vaccinated so far are elderly people who are more likely to be suffering from many other conditions and it is impossible to identify if it was the vaccine that caused the issue or not.
Watch: Should we be worried about the Oxford/AstraZeneca vaccine?