Human bodies play host to - are symbiotic with - a wide variety of normally occurring bacteria which in their turn share their micro-environment in our tissues with smaller organisms, namely viruses. Thus there is in the healthy individual an equilibrium between these assorted bugs in, for example, the human respiratory tract.
When antibiotics are given, especially "wide spectrum antibiotics", many bacteria are killed off leaving the viruses - which are not affected - to proliferate unchecked. Anti-viral agents are few and tend to be very toxic.
Dr H C GRANT
London NW3Reuse content