What are the ingredients? 

All of the approved COVID-19 vaccines are free from animal products, including egg. They have also been approved for use by the Muslim Council of Britain, senior rabbis and other faith communities. The British Islamic Medical Association has also confirmed that the vaccine is allowed during Ramadan because it does not invalidate the fast.

The NHS has published the full list of ingredients to each of the vaccines. 

How does a vaccine work?

The COVID-19 vaccine, just like any other vaccine, works by teaching your immune system how to defend itself against attack from the virus. The vaccine contains a harmless bit of the virus, so that your body produces white blood cells. If you were then to become infected with COVID-19, your body would have the ‘memory’ of the partial bit of the virus and would be able to fight it immediately. None of the vaccines contain a live form of the virus in them.

You can find more infromation on the NHS website.