2.3 Immunization strategies

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    2.3.1 Routine vaccination

    Measles vaccination is included in all national immunisation programmes. Routine vaccination is usually done at fixed sites and outreach sites and by mobile teams. 
     

    Fixed site 

    Regular immunisation activities are conducted by the health care facility personnel, who have a refrigerator. This is assumed to cover the population within a radius of 5 km of the fixed site. 
     

    Outreach site 

    Regular and scheduled immunisation activities are conducted by health care facility personnel, who travel with a passive cold chain (vaccine carriers). The outreach strategy can cover populations living from 5 to 15 km from the health care facility. 
     

    Mobile team 

    Scheduled immunisation activities are conducted by mobile teams that travel around according to a pre-set schedule. Substantial resources are made available for transportation, for vaccine storage (cold boxes and vaccine carriers) and for training the teams. This strategy requires careful organisation and informing the remote populations that one wants to reach (> 15 km) beforehand. 
     

    2.3.2 Mass vaccination campaign

    Vaccination campaigns are one-off activities that allow a large number of people to be immunised in a short period of time by setting up multiple vaccination sites.

    They are done as a preventive measure as part of catch-up campaigns, or as a pre-emptive measure when the risk of imminent outbreak is high (e.g. influx of displaced populations or in high-risk areas near an ongoing outbreak), or as a response when an outbreak has been detected.

    The campaigns mobilise a lot of personnel and resources and require good coordination between partners. 
     

    Catch-up campaign [1]Citation 1.World Health Organization. Catch-up vaccination. Published January 2025. Accessed March 21, 2024. Available from: 
    https://www.who.int/teams/immunization-vaccines-and-biologicals/essential-programme-on-immunization/implementation/catch-up-vaccination
     

    Supplementary immunisation activities (SIAs) [2]Citation 2.World Health Organization. Immunization in practice: a practical guide for health staff, 2015 update. WHO; 2015. Accessed March 21, 2025. https://iris.who.int/bitstream/handle/10665/330568/9789241511254-eng.pdf?sequence=1&isAllowed=y

    The purpose of these campaigns is to give children a second dose of vaccine and to “catch up with” children who did not receive routine vaccination. They are scheduled and conducted every 2 to 4 years as part of the international measles control programme.

    They non-selectively target children: 

    • Starting at 9 months of age (or 6 months of age in disease outbreak contexts)

    • Up to age 14 years during the initial campaign (called the catch-up SIA) and then up to age 59 months (or 9 years) for subsequent campaigns (called follow-up SIAs). The target age group can be different if the vaccination is for measles and rubella.


    The vaccine dose administered during SIAs is considered a supplementary dose and is not included when calculating the administrative coverage of routine EPI. It is not always entered on the child’s immunisation record. 


    Periodic intensification of routine immunisation (PIRI)

    These are intermittent local immunisation activities of limited duration to catch up with unvaccinated children after access to routine vaccination has been disrupted. It can involve several diseases on the immunisation schedule. The immunisation record is completed, and the data are included in the calculation of administrative routine EPI coverage. 
     

    Pre-emptive campaign 

    Pre-emptive campaigns aim to avert an outbreak when the risk is high in a localised geographic area. 

    Areas can be identified for pre-emptive vaccination based on the lack of recent SIAs, inadequate routine vaccination (EPI dysfunction, vaccine shortages or health care facility closures), or access problems (e.g. lack of geographic or financial access, security issues, or weather events). 

    Proximity to current disease foci and the population’s inherent risk are also considered when identifying areas needing an immediate pre-emptive campaign.  

    Vaccination will target the highest-risk age group, which can vary according to context. The factors to consider when choosing are the age distribution of cases, vaccination coverage in recent years, the history of outbreak response campaigns or SIAs, events impacting the EPI, and factors that affect the size of the cohort (or the birth rate).  

    Outbreak response campaign


    The outbreak response campaign is one component of epidemic management. Its aim is to limit 
    the spread of the outbreak by vaccinating the entire at-risk population as quickly as possible.
     

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