Introduction - Uppsala Monitoring Centre

Vaccines
pharmacovigilance data.
When Jenner wrote on vaccination in 1796 it would have been welcomed as
smallpox was prevalent and frequently fatal at that time. However, as smallpox
waned under the influence of vaccination people would have been less aware of any
immediate benefit and adverse effects would have been less acceptable.
Vaccines tend to be given to young healthy persons and, therefore, there are
much more stringent demands as far as safety is concerned. Variolation dates back
to 12 th century in China and arrived in the Western world in 1721 to be supplanted by
vaccination in 1800. Variolation 153 was prohibited in 1840. From the start there have
been strong anti-vaccination movements citing: inefficacy, threats to individual liberty,
religious opposition and lack of safety. The Vaccination Act of 1853 (UK) made it
mandatory for infants under 3 months old and in 1867 this was extended to 14 years
of age, but in 1898 conscientious objection was allowed. Under these circumstances
it was even more important that safety was confirmed.
Nervous sequelae of smallpox vaccination had been known since 1802 and
encephalitis from 1912, but was not reported until 1926 (McMenemey, 1960). It is
not known why it wasn’t reported earlier. The latter with a case mortality of 44% and
an incidence of 1 in 6,600 at the time of a 1942 smallpox outbreak (Fyfe & Fleming,
1943). The incidence rate is 2.9 per million and the latest mortality figure is 28.9%
(Aragon et al., 2003). Severe local reactions with swelling, oedema of the arm,
adenitis and radiating pains were known from early days and contamination of the
vaccination site was not uncommon (Fox, 1902). Generalised vaccinia 154 had an
incidence of between 1 in 57,000 and 1 in 75, 000. Latest incidence figure is 1 in
25,000 with no fatalities (Aragon et al., 2003).
The last recorded valid case of smallpox was on 26th October 1977.
New vaccines against specific diseases have been produced: anthrax in1881,
rabies in 1885, plague in 1897, diphtheria in 1923, pertussis in 1926, TB and
tetanus in 1927, yellow fever in 1935 and polio in 1955. The WHO lists four different
types of adverse events:
Vaccine induced AEs, e.g. allergic reactions
Vaccine precipitated AEs, e.g. febrile seizures
Programmatic errors, e.g. abscess due to poor sterilization
Coincidental errors
Types of ADRs with these vaccinations:
The ADRs which are common and not serious are: local reactions, fever,
153 Variolation = deliberate innoculation with unmodified smallpox virus
154 Vaccinia= systemic spread of virus(cowpox) from the innoculation site causing wide spread pocks