5.4.13. How can the level of vaccination coverage achieved be estimated?

Vaccination coverage can be estimated using several methods:

- Post-vaccination questionnaire surveys can estimate the proportion of vaccinated to unvaccinated dogs in households. During these surveys dog owners should be asked to produce vaccination certificates in order to identify dogs vaccinated in current vaccination campaigns. This method can also be used to investigate the reasons why people did not vaccinate their dogs. This method may not include community or ownerless dogs and can therefore overestimate the vaccination coverage in free-roaming dogs; the dogs most critical to vaccinate to end enzootic transmission. See here for examples.

- From direct observation of marked and unmarked dogs, Vaccinated dogs can be easily identified shortly after the campaign if they are marked using a temporary paint or collar (see here), or later if they are permanently marked, for example during capture-neuter-vaccinate-release (CNVR) campaigns. Examples of Capture-mark-recapture methods are here. This method can be applied very soon after the campaign has been completed, and can quickly identify areas where further vaccination efforts are required, before the vaccination team moves away.
Consideration of the duration of marks should be made when designing an evaluation. Collars may be lost quickly, or removed and paint marks may wash off after several days. Permanent marking techniques are not appropriate in all settings, particularly in areas where a permanent mark will leave exposed wounds that can become infected or parasitized. Marking dogs that have been vaccinated orally can be a challenge as the dogs are being not handled, but programmes have successfully used 50-100ml syringes filled with dyed water to mark dogs.

Restricted vaccinated dogs that are kept inside the house or backyard are often not observed. Hence, this method is less suitable for the overall dog population but can be used to determine the vaccination coverage of the free-roaming dog population.

- From doses of vaccine used in relation to the estimated dog population. This method requires calculations using good estimates of the overall dog population as the denominator value. Many programmes have found that initial dog estimates based on dog registration data or extrapolated from assumed human:dog ratios have turned out to be very inaccurate. The level of vaccination coverage calculated using this data is generally overestimated, sometimes several-fold. In these settings campaigns relying on unstable estimates should make a concerted effort to ensure that more dogs are vaccinated in each area after each successive campaign.




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