smallpox vaccine and vaccination in the intensified ... - libdoc.who.int

considerably more than was required, accord-
ing to the experimental work.
However, since the improvements in vac-
cine production procedures, outlined in the
earlier part of this chapter, ensured that
highly potent vaccine was available, titres in
excess of those shown to be necessary in trials
were recommended so as to provide a safety
margin to allow for the effect of the problems
in the handling of vaccine that would inevit-
ably occur in the field at some time or
another.
Application
Provided that the instruments could be
properly maintained, jet injection, using the
special nozzle for intradermal injection, had
obvious attractions for mass smallpox vacci-
nation campaigns. In 1965 Millar and his
colleagues in CDC undertook a pilot study of
jet injection and multiple pressure vaccina-
tion in Brazil, the results of which stimulated
that country to undertake a national smallpox
eradication programme (Millar et al., 1971).
They reported that between 27 January and
15 February 1965,47 926 residents of AmapP
Territory, Brazil, living in both urban and
rural areas, were vaccinated, all by jet injec-
tion. For purposes of comparison, the tradi-
tional multiple pressure method was used in
MazagHo, where 34 vaccinators, 2 supervisors
and 2 local staff vaccinated 91 1 persons in 3
hours. In AmapP town, in contrast, 2 jet
11. VACCINATION IN THE INTENSIFIED PROGRAMME 577
vaccinators, 1 recorder and 2 local staff
vaccinated 1335 persons in 6 hours (Table
11.1 9).
Using data obtained in part of this trial and
those collected in a conventional mass vaccination
campaign in Belkm, Millar et al. (1 971)
analysed the relative costs of the two methods
(see Chapter 12, Table 12.5). Jet injection was
found to reduce manpower, transport and
vaccine requirements and appeared to be
more efficient. In urban campaigns it was
estimated that iet iniection costs were about
one-third of those of conventional techniques.
They concluded that jet injection, if
intelligently applied, could significantly increase
the speed, efficacy and efficiency
of national mass smallpox vaccination
- programmes.
CDC launched a small~ox eradication and
measles control programme in 20 countries of
western and central Africa in 1967, as part of
the WHO global smallpox eradication programme
(see Chapter 17). The use of the jet
injector was regarded as the key to this
programme, since it not only reduced the
needs for manpower, transport, the quantity
of vaccine and the chances of unsuccessful
vaccination but also made possible simultaneous
vaccination against smallpox and
measles. In 1966, when the Director-General
of WHO submitted a report to the Nineteenth
World Health Assembly on the organization
of the global programme, he specifically
referred to the usefulness of intradermal jet
Table 1 1.19. Comparison of multiple pressure and jet injection vaccination techniques In 2 towns in Amapd
Territory, Brazila
Characteristlc
Populatlon
Campalgn method
lnoculation technique
vacclne:b
Titre (pock-forming units per ml)
Dose
Amount (tubes)
Vacclnatlons:
Number vaccinated
Number of vacclnators
Vaccinations per man-hour
Percentage of populatlon vaccinatedC
Take rates (%):
Total
Primary
Revacclnatlon
a From Mlllar et al. ( i 97 1 ).
Egg vaccine was used.
C Based on post-campaign survey.
974
House-to-house visltlng
Multiple pressure
1 08.0
l drop
17
Town
Mazaglo AmapA
1 638
Collecting point and "street sweep"
Jet Injector