Conspiracy theorist

Eric Bahrt may be factually correct in both his recent letters concerning the polio vaccine. However, he has missed at least one important point. As I understand it, the vaccine delivered orally contains an attenuated virus, which stimulates an immune response without giving you polio. This attenuated virus may be passed from one person to another. Thus, although not everyone receives the vaccine, they may still benefit from the vaccination programme by “catching” the attenuated virus strain. This would explain why herd immunity may be achieved without necessarily vaccinating everyone.

Perhaps more importantly, Mr Bahrt seemed to be implying in his first letter that vaccination is some kind of weird conspiracy, though I may have misunderstood him. It is not entirely clear precisely what he believes. Perhaps he might care to state his views explicitly.

NIGEL WOODWARD