From Deborah Potts, School of Oriental and African Studies, University of London
“A plague unleashed”, your article about the possible link between HIV and
mass vaccination campaigns starting in the 1950s in Africa made grim reading
(30 September, p 16).
Surely it would take more than one needle used seven times to
cause the terrible chain of events hypothesised as SIV mutated into HIV? The
process of serial transmission described suggests that the virus would need time
to replicate and mutate in an individual before it was passed on by a(nother)
reused needle, perhaps years later, and that this would have to occur about
seven times before the virus became pathogenic.
The possibilities of such a sequence being broken seems very high in
societies where many vaccination campaigns may have been “one-offs”, access to
modern healthcare for most was limited, and the rate of transmission of the
virus by injection was only about 1 in 300. Perhaps this explains the time lag
up until the 1980s before the virus took hold? Mass immunisation campaigns to
protect children against common childhood diseases would presumably also be
unlikely to contain individuals well advanced on this dreadful transmission
route.
