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CBSE Class 9 Answered

yesterday i learnt that if a person had small pox once he will not be affected by it again because immune system recognise it and fight with it but why do we get cold so many times again and again\
Asked by | 30 Nov, 2012, 09:06: AM
answered-by-expert Expert Answer
Common cold is caused by more than 200 different types of viruses such as rhinovirus, coronavirus , adenovirus etc. Immunity to one type of viruses does not protect against the other types of viruses. When we get cold once, we gain immunity from that particular type only, not from the others causing common cold. So next time we fall sick, it is because of another strain or type of virus.
Answered by | 30 Nov, 2012, 10:33: AM

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