Multitude of reasons: Most importantly is that viruses keep mutating, i.e. Keep changing its form, and go deep into the nucleus of the living cell so becomes hard to reach, but there are some antiviral drugs that can kill those tiny creatures, much smaller than the large bacteria, most famous is acyclovir (zovirax)
Answered 11/3/2015
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2 doctors weighed in across 2 answers
2 doctors weighed in across 2 answers
A doctor has provided 1 answer
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