5.4.5. What methods and strategies are available for dog vaccination?

The choice of vaccination method and strategy is critical to ensure enough dogs will be vaccinated to break the cycle of rabies transmission.

Characterising the dog population (see here) can help decide which vaccination methods and strategies will led to the most successful campaign outcome.

Current methods include parenteral vaccination and oral vaccination (ORV), and each can be delivered by a variety of different strategies. A single strategy or a combination of strategies should be selected on the basis of the setting or known socio-cultural factors and the accessibility of the dog population. Different vaccination methods may also be combined within a campaign in order to achieve sufficient vaccination coverage.

Central point vaccination in Payatas, Manila, Philippines. Photo: Geloy Conception/GARC

Vaccination strategies available for parenteral dog vaccination are as follows:

 Continual vaccination at fixed vaccination posts. Dog owners take their dogs/cats at any time to well-recognized sites (such as private or government veterinary clinics). Although this technique requires little government effort, it may fail to reach many owned and all unowned dogs resulting in poor population coverage or coverage that is difficult to measure.
 Central-point vaccination strategy. Mobile teams set up temporary vaccination points at a central location within villages or cities conveniently located for dog owners. This strategy is relatively inexpensive and can achieve the recommended level of coverage (See CASE STUDY TANZANIA and other examples here). Additionally, a mobile team can travel around city streets or other public areas in search of roaming animals. There may be a need to estimate the size of catchment areas of temporary clinics and decide on their spacing accordingly.
 House-to-house campaigns. Vaccination teams travel to individual houses to vaccinate dogs. This strategy may be required in remote areas or where owners cannot leash their dogs. It usually results in a sufficient percentage of dogs being vaccinated, and it causes only minimal disruption of the normal community functions, but it is costly and logistically difficult (CASE STUDY TANZANIA).
 Capture/vaccinate/release. Where large populations of fractious, or ownerless dogs exist, mobile vaccination teams may need to travel through the streets accompanied by dog catchers. Dogs are captured (usually in a net), vaccinated and then released immediately (see the study in India here).

Vaccination strategies available for oral dog vaccination are as follows:

 House-to-house handout. This can easily be incorporated into a house-to-house parenteral vaccination campaign and all dogs not accessible for parenteral vaccination (used as a first choice) are considered for oral vaccination. Bait is distributed to individual dogs and they are observed as they consume the bait and waste is removed immediately. This method is generally preferable as it avoids unnecessary exposure to the vaccine by people, or animals other than dogs.
  Distribution of baits to dog owners. This involves relying on dog owners giving the bait to their dogs. As the vaccination is generally not observed, its success may be difficult to assess.
 Wildlife immunization model. ORV baits are distributed in the environment. This is only generally applicable in very specific cases such as with true feral dogs.

Further guidance on oral vaccination is available here. Any time the use of ORV in a campaign is being considered, the safety profile of the vaccine must be evaluated prior to its widespread use. WHO recommends that a risk assessment is conducted prior to distributing baits to ensure that human risk of exposure or adverse events are mitigated (see here).

Parenteral vaccination of dogs remains the cornerstone of dog rabies control and can be used for passive vaccination strategies, such as vaccination at fixed points. However, in many areas not all dogs can be restrained and are therefore inaccessible for vaccination. Some dogs are aggressive when handled and these as well as unowned dogs will likely require the implementation of more active vaccination methods (such as CVR). Click here to learn about restraining and inoculation techniques for parenteral immunization.

However, in some cases trying to catch and restrain dogs may not be feasible or may be very time and labour intensive. Here, oral vaccination could be used as a supplementary tool: all dogs not accessible for parenteral vaccination could be offered a bait containing a vaccine-loaded blister. Oral vaccination using baits has been used to vaccinate dogs in field trials (see these studies). In some areas, programmes have combined delivery of oral vaccination baits with parenteral vaccination (CASE STUDY PHILIPPINES) (CASE STUDY TURKEY) (CASE STUDY KWA-ZULU NATAL). However, the use of oral vaccine baits is still experimental and further field studies are needed to evaluate its’ effectiveness. Depending on the region, dogs may prefer locally made baits instead of those provided by the supplier.

Independently of the methods and strategy adopted, synchronized campaigns (e.g., one-day or one-week campaigns covering whole municipalities or states) may be very effective in mobilizing many sectors and the public, in view of the short duration of their involvement and higher media and public profile.

If dog owners must pay for vaccination, their participation in campaigns may be reduced. Offering free vaccinations is generally recommended, but other models of recovering costs from owners may be possible (see section 3.3.5). Sometimes incentives, such as dog collars, are offered as a way to increase participation in vaccination campaigns (see here for an example), but care must be taken to not raise the cost of the programme, or reduce participation if these are not provided in the future.

Photo courtesy of the Serengeti Carnivore Disease Project

Measuring the vaccination coverage level achieved by any method (at least after initial campaigns, and maybe after every campaign) is very important if the success of the campaign is to be assessed, and improvements are to be made. Investments in assessing the coverage level achieved can be well worth it if adjustments are made to enable sufficiently high coverage to be achieved and rabies is eliminated in a shorter timeframe. See here for an example of where low coverage in some areas allowed rabies to persist. In many cases, errors in the initial dog population size or composition estimates can be corrected by assessing the proportion of all dogs that have been reached by a campaign. A more effective campaign can then be designed from these findings if necessary. See section 5.6.2 for more information.