Since the group A virus is the only type of the virus that can be transmitted naturally, it is the only type that the vaccine needs to contain.
(A virus; is; the only type of the virus) (the virus; can be transmitted naturally; ) (it; is; the only type that the vaccine needs to contain) (the vaccine; needs; to contain) Context(the vaccine needs,List([114, 131))):(the only type; to contain; the vaccine)
the vaccine needs,List([114, 131))
A virus the virus it the vaccine the only type
is can be transmitted naturally is needs to contain
the only type of the virus
the only type that the vaccine needs to contain
to contain
the vaccine