Vaccination coverage is growing in low- and middle-income countries, yet some communities are being missed entirely.
Many communities across low- and middle-income countries do not have health facilities. This is why it is important that outreach vaccinators visit these communities regularly, to protect citizens against vaccine-preventable diseases, such as measles or polio. While routine immunisation is effective for vaccinating large numbers of children in towns or cities, it often misses the mark for remote communities, where caregivers may not even realise their children require vaccines.
The importance of outreach vaccinations
In low- and middle-income countries, communities are often located many kilometres from the nearest health facility. For example, there has recently been an outbreak of circulating vaccine-derived poliovirus type 1 (cVDPV1) in the Democratic Republic of the Congo (DRC), with approximately 100 cases reported in 2023. This is a rare strain of poliovirus that can cause paralysis. Almost 99% of these cases have been concentrated in the southeastern provinces of Haut-Lomami, Tanganyika, and Haut-Katanga. And within these provinces, over 80% of cases are located in districts featuring rivers, lakes, or other remote locations that are difficult to reach.
Polio vaccinators travelling via canoes to reach citizens in riverine communities.
However, in low- and middle-income countries, the number of outreach vaccination sessions available is often too low. For instance, we have seen regions across some countries where four outreach sessions are held per month, even though 16 is the number needed to provide enough vaccines.
Pursuing targeted outreach
Routine immunisation efforts are important, but they often miss hard-to-reach areas, such as the riverine communities of the DRC, which can only be accessed by boat. Targeted, region-specific analysis is crucial for ensuring that outreach sessions are conducted in all of the right places. Using the knowledge of local teachers, local community leaders, and state stakeholders, is an effective way of discovering where children in need of vaccinations can be found in these communities.
Combining local knowledge with geospatial data is another important step for locating "zero-dose" children. This data can be retrieved through thousands of interviews with caregivers, each revealing the immunisation status of their children in local communities. Once the data is collected, hard-to-reach locations are then mapped, with maps printed to aid vaccination teams in visiting the right communities.
In the DRC, Acasus supported the government in countering the poliovirus outbreak with various tailored vaccination strategies. From February 2024, the STOP strategy was launched to halt cVDPV1 transmission in the DRC's southeastern provinces. Over 150 outreach vaccination teams were hired, with each team assigned to an operational zone including 20+ hard-to-reach communities. This helped to ensure full vaccination coverage, while additional boats were provided to enable vaccinators to reach riverine communities. Other vehicles, such as motorbikes, were also used to give vaccinators access to remote communities.
Polio supervisors travelling through a hard-to-reach community lacking roads to reach citizens.
By utilising geospatial technology to track real-time vaccination coverage, it was discovered that over 70% of communities had been reached three times or more by December 2024. This included over 74,000 children receiving their first vaccinations against polio, while 58,000 of these children are now fully vaccinated against the disease. Meanwhile, only one cVDPV1 case has been notified in the DRC's southeastern provinces since the STOP campaign began.
Outreach monitoring is potentially the only option for millions of children to receive life-saving vaccinations across various low- and middle-income countries. With large numbers of children being missed through routine immunisation efforts, it is critical to pursue targeted outreach.
