<Tr> <Th> Type </Th> <Td> Attenuated virus </Td> </Tr> <Tr> <Th_colspan="2"> Clinical data </Th> </Tr> <Tr> <Th> Trade names </Th> <Td> Varivax, Varilrix, other </Td> </Tr> <Tr> <Th> AHFS / Drugs.com </Th> <Td> Monograph </Td> </Tr>

When did the chicken pox vaccine become required