The latest WHO and UNICEF data on global immunization coverage show that 86 percent of the world’s children received the required three doses of diphtheria-tetanus-pertussis containing vaccines (DTP3) in 2015, a coverage level that has been sustained above 85 percent since 2010. As a result, the number of children who did not receive routine vaccinations has dropped to an estimated 19.4 million, down from 33.8 million in 2000.
However, this progress falls short of global immunization targets of the Global Vaccine Action Plan (GVAP) for the Decade of Vaccines of achieving 90% or more DTP3 vaccination coverage at the national level and 80 percent or more in all districts in all countries by 2015.
Gaps in immunization coverage
Among the 194 WHO Member States, 126 countries achieved and sustained the 90% immunization target for DTP3, up from 63 in 2000. Many of these countries, especially the low and middle income countries, need to continue strengthening their health systems as they add vaccines to their national programs so that coverage with all vaccines reach and sustain at the 90% or more target.
Countries such as Congo, Guatemala, Iraq, Mauritania, Philippines and South Sudan have experienced recent decline in coverage due to under-investments in national immunization programs, vaccine stock-outs, disease outbreaks or conflicts and have not been able to establish or maintain strong health systems that are needed to sustainably deliver vaccination services to reach and sustain high immunization coverage.
Six countries had less than 50 percent coverage with DTP3 in 2015, many of which are fragile states and affected by emergencies: Central African Republic, Equatorial Guinea, Somalia, South Sudan, Syrian Arab Republic and Ukraine.
Inequities in immunization coverage
In addition to generating estimates of national immunization coverage, WHO and UNICEF also collect and report data on coverage at subnational levels. National coverage estimates often mask large inequities in coverage within countries. Achieving high and equitable coverage requires targeted actions at subnational levels.
There were 158 countries that reported coverage estimates at the district level for 2015. While WHO and UNICEF estimates showed that 126 countries had DTP3 coverage of 90 percent or more at the national level, only 90 countries reported subnational coverage. Of these, only 53 countries had coverage of 80 percent or more in all districts. Worldwide, of the 32,201 districts from which data were available, 25 percent had coverage below 80 percent; the proportion could be higher given the nature and quality of the administrative coverage data at the district level.
WHO and UNICEF are increasing efforts to gather subnational coverage data and support countries in improving the quality and use of the subnational coverage data to take actions to achieve high and equitable immunization coverage.
Introducing under-utilized vaccines
The updated WHO/UNICEF estimates also show that coverage with vaccines other than DTP, has improved. Worldwide, the number of children protected against hepatitis B is high and increasing steadily. In 2000, just 29 percent of children received three doses of vaccine against the viral disease; this has increased to 84% in 2015. However, more still needs to be done to ensure that all infants receive a hepatitis B vaccine dose within their first 24 hours of life.
Only three countries China, Russia and Thailand have yet to introduce Haemophilus influenzae type b (Hib) vaccine, a globally recommended vaccine. Global coverage of Hib vaccine is 64 percent. However, in countries that are using the vaccine in their national immunization programs, coverage is similar to DTP3. Generally, Hib and DTP vaccines are used together in combination vaccines, which help to achieve the same levels of coverage as DTP in countries using the vaccine.
The number of countries using new vaccines such as rotavirus and pneumococcal conjugate vaccine has increased, but challenges remain.
While 128 countries introduced pneumococcal vaccine in national immunization programs, global coverage for three doses of the vaccine reached just 37 percent in 2015. Among the middle income countries, the vaccination coverage is only at 24 percent with 58 out of 104 countries using the vaccine in their national programs. However, vaccination coverage in low income countries is at 68 percent with 24 out of 31 countries using the vaccine, mainly with support from Gavi, the Vaccine Alliance and 84 percent in high income countries, with 45 out of 57 countries using the vaccine.
Additionally, rotavirus vaccine was introduced in 81 countries and global coverage reached 23 percent in 2015. This also shows under-performance in middle income countries, where vaccination coverage only reached 16 percent with 44 out of 104 middle income countries using the vaccine; compared to 44 percent vaccination coverage in low income countries with 18 out of 31 countries using the vaccine, also mainly with Gavi’s support; and 40 percent vaccination coverage in high income countries with 19 out of 57 countries using the vaccine.
Tracking global plan
In October 2016, the WHO Strategic Advisory Group of Experts on Immunization (SAGE) will review progress against the GVAP targets, including the immunization coverage targets, and provide its assessment of progress and recommendations for corrective actions for discussion at the World Health Assembly in May 2017.
Source: World Health Organization (WHO)