Immunization

The big picture

© UNICEF/HQ02-0238/Geenen

After receiving their individual vaccinations against measles, a crowd of children stand outdoors, each holding a card that reads ' measles Campaign 2002 - I have been immunized' at the Mirera Primary School in the province of the Rift Valley

Immunization is the most successful and cost-effective public health intervention that has consistently reached close to 80 per cent of young children in recent years, averting more than 2.1 million deaths annually and countless episodes of illness and disability. Immunization also has the potential to boost economic growth and many cost benefit analysis of vaccination have shown positive impact. The infrastructure, programme management and acceptability of immunization programme offer a platform to deliver other integrated health and nutrition interventions.

Vaccines works by providing the immune system with harmless form of an antigen: a portion of the surface of a bacterium or virus that the immune system recognizes as "foreign.” A vaccine may also provide a non-active version of a toxin — a poison produced by a bacterium — so that the body can devise a defence against it.

Coverage with three doses of DPT vaccine (combined diphtheria, tetanus and pertussis) is the globally agreed proxy indicator of country and regional performance of routine immunization programme. The recent estimates for the year 2006 show positive trends in the global vaccine coverage with 79% coverage through a record of 102 million children under one year of age vaccinated with three doses of DTP vaccine.

There are disparities in immunization coverage between the regions and countries.  The DTP 3 coverage is 96% in the industrialized countries and none of the other regions in South Asia and Sub Saharan Africa could attain this high coverage leaving a large un-immunization population in the least developed countries . In addition, the inequity of coverage prevails within many countries, specially the developing countries in South Asia and Sub Saharan Africa.

Notable progresses have been made in introduction of new and underused vaccines such as Hepatitis B and Haemophilus influenzae type b (Hib) vaccine. By 2006, 164 countries have introduced hepatitis B vaccine (HepB) into their routine immunization schedule for infants.   Although the progress for Haemophilus influenzae type b (Hib) vaccine is not as good, with only 104 counties having introduced it by 2006, considerable further progress was made in 2007 with nearly 20 additional countries approved to introduce it, mostly as the pentavalent combination vaccine: DTP-HepB-Hib. 

Significant progresses have been made in reducing mortality and morbidity due to vaccine preventable diseases such as polio, measles and maternal and neonatal tetanus through supplementary immunization activities or campaigns. These immunization campaigns provide excellent opportunities to reach children with higher age group compared to routine vaccine and also to add other high impact life saving interventions such as Vitamin A, Insecticide treated nets and de worming tablets. However, despite these achievements still approximately 26.3 million children do not receive a full schedule of routine vaccine every year. There are daunting challenges in reaching all target children with routine vaccines. The vaccine cost has increased in the last few years. The cost of providing traditional and new vaccines (hepatitis B and Hib) has gone up to $20-$40 per child vaccines. The other barriers identified for low vaccine coverage ranges from non availability of sustainable resources to poor management and logistics systems to inequity in services to lack of community engagements.