POST 00671E : VACCINE FORECAST
Follow-up on Posts 00649E and 00662E
8 May 2004
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This posting contains two contributions. The first comes from Julie
Milstien (mailto:
[email protected]) or
(mailto:
[email protected]) and the second from Elly Tumwine
Rweizire (mailto:
[email protected]) from Uganda.
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Alejo is correct - the demand forecasting equations do not work very well
at the individual health center level because of the need to factor in
session size/outreach. However, building up a composite forecast for a
country based on a session size (or teamwise) analysis of each health
center is not a feasible solution.
Therefore we are left with the equations. As Olivier and Patrick say, once
a country has experience with a product, it is fairly straightforward to
build a demand forecast, based on usage of the previous years and factoring
in things that might change (target population, expected coverage, wastage,
presentation). It is only when you are starting from scratch that it gets
complex, particularly so if the introduction of a product will be
rolled-out, or if a country is trying to increase coverage and decrease
wastage at the same time. Thus the advice to be conservative in the first
year so as to avoid stockouts.
Julie
Dr Julie Milstien
University of Maryland School of Medicine, Center for Vaccine Development
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Some help me out of this confusion.
Vaccine forecasting for antigens with more than one dose in schedule, it is
clear with the attached WHO guidelines.
· The target population as explained in the WHO rationale should be birth
cohort since immunizations start as early as at birth for OPV and 6 weeks
for DPT.
· The first dose coverage should be used as explained in the WHO rationale
to avoid the complications of figuring out DPT1-DPT2, DPT2-DPT3 drops out.
The complication however remains for countries with low routine coverage
that vaccinate children who did not complete their schedule and come when
they are 12 months - 24 months. Some country policies allow for immunizing
such kids. Should this be taken care of in the wastage factor or should
such countries document numbers and calculate for this proportion based on
previous records. Theoretically everybody should complete the schedule by
11months.
Forecasting using sessions has its shortfalls.
· Session size varies by immunization unit catchment area population
(health centre and hospitals) and seasonality within individual units.
· Session frequency varies by immunisation units depending on the
consistency of logistic support (supply of vaccines and injection
materials, transport, allowance for staff). Where outreach strategy is
employed, a number of countries prefer to make integrated outreaches and
may also be affected by the logistics of other components other than
immunisation.
If birth cohort is used as a denominator for estimating coverage for DPT1
for vaccine forecasting, should it also be applied to estimating coverage
for measles, which is given at nine months? Should this be the same
denominator for calculating coverage at the end of the year?
Elly Tumwine Rweizire,
Country logistician
UNEPI (EPI Uganda)
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