Salk did a lot of work at this time in an attempt to discover whether a vaccine containing live viruses was the most efficient way to provide a patient with immunity or whether a vaccine containing only dead viruses would work just as well.
(Salk; did; a lot of work; T:at this time; L:in an attempt) (a vaccine; containing; live viruses)
Salk a vaccine
did containing
a lot of work T:at this time L:in an attempt
live viruses