If you haven't already had a coronavirus vaccine. It's likely you'll be offered one at some point. For many people this can't come soon enough but others may feel wary about having a new vaccine. (23) it makes them feel unwell. First, let's look at how some of them work to see why they can't give you Covid. mRNA vaccines use a tiny piece of the virus’s genetic code called messenger RNA. This is how Pfizer/ BioNTech and Mordern's vaccine are made. Viral vector vaccines carry DNA that contains a piece of coronavirus genome. This has been put into a less harmful virus that's been weakended. So it can't (24) you ill. It’s how the Oxford/ Astrazeneca vaccine is made. The DNA or mRNA, work by instructing your cells to make lots of tiny'spike proteins. These are usually found on the surface of coronavirus but they are harmless on their own which is why you can't catch Covid from these vaccines. But the spike proteins are enough to make your body think it's been ( 25 ) which gives it the information it need to protect against future attacks . Other vaccines contain parts of coronavirus and some , like Coronavac and Covaxin, contain the whole virus. This is inactivated ( 26 ) it cannot cause infection. It's normal for people to suffer mild symptoms after being vaccinated such as a headache or a raised temperature . This is not the disease itself , but the body responding well to the vaccine. It shows you're having an immune response . Millions of people have already had a vaccine and very ( 27 ) have reported severe side effects , like an allergic reaction. But, as with most medicines there is always a risk. Because of this there are groups of people who may be advised against vaccination in case it makes them unwell. Those who are allergic to a specific ingredient for example should be offered an alternative vaccine. Advice varies between countries and should be available on your government website or through your doctor. ( 28 ) around the world have been working hard to ensure the safety of coronavirus vaccines. And as more people are vaccinated against Covid we should be able to gradually return to our normal daily lives. 23. A. In case B. If C. As long as D. Unless 24. A do B. make C.cause D. help 25. A. infected B. infecting C. infectious D. infective 26. A. because B. however C. and D. so 27. A many B. much C. few D. little 28. A. Doctor B. Environmentalists C Scientists D. Conservationists