Interview conducted by April Cashin-Garbutt, BA Hons (Cantab)
Please could you give a brief introduction to the diphtheria-tetanus-pertussis (DTP) vaccine?
This vaccine is sometimes also called the “triple vaccine” and has been around for about 50 years, and it protects against diphtheria, tetanus, and pertussis. These are serious diseases caused by bacteria.
Diphtheria and pertussis are spread from person to person. Tetanus enters the body through cuts or wounds. Diphtheria causes a thick covering in the back of the throat, which can lead to breathing problems, paralysis, heart failure, and even death. Tetanus (also known as “lockjaw“) causes painful tightening of the muscles, usually all over the body.
Pertussis (also known as “Whooping Cough”) causes coughing spells so bad that it is hard for infants to eat, drink, or breathe. These spells can last for weeks. It can lead to pneumonia, seizures (jerking and staring spells), brain damage, and death.
How many times does the DTP vaccine need to be administered in order for it to be effective? At what ages should it be administered?
DTP vaccine is normally administered in three doses within the first six months of life, and followed up in some countries with booster doses in the second and fifth year of life.
Frequently DTP is put into a combination vaccine that may also contain vaccine against Haemophilus influenzae type B (which may cause severe meningitis in infants), hepatitis B vaccine (which causes liver disease later in life) and others.
Also, it should be noted that DTP vaccine is only one of many other vaccines that should be given to infants to protect them against very serious diseases such as polio, measles, rubella (“German measles”) and others.
How many people currently receive the three recommended doses of the DTP vaccine?
It is estimated that in 2011 107 million children (83% of the world’s infants) received three doses of DTP vaccine, leaving 22.4 million children who have not received these three doses. This third dose of DTP (DTP3) is used by countries and global partners as one measurement of the country’s vaccination programme performance and is used as a proxy of the health system of that country to reach its population.
Another measurement is the percentage of infants that have received all recommended vaccines according to the specific country’s vaccination schedule; this measurement is called the “coverage of fully immunized children”, and is estimated to be much lower than DTP3 coverage, namely approximately 76%. (estimated based on minimum coverage of all vaccines in routine immunization schedule after 1 full year of national introduction and administered by 1 year age)
How have the vaccination rates of DTP3 changed over the years?
In 1974, WHO established the Expanded Programme on Immunization to ensure that all children had access to routinely recommended vaccines. Global coverage with the third dose of diphtheria–tetanus–pertussis vaccine (DTP3) was <5% in 1974 and increased to 79% by 2005, and to 83% in 2011.
Other vaccines have followed a similar trajectory of coverage, so as an example the global percentage of infants vaccinated against measles is 84% in 2011.
Why are some children still not receiving the DTP and other childhood vaccines?
In every country of the world there are children that still do not receive DTP vaccine or indeed the other infant vaccines. However the largest number of children that do not receive DTP3 vaccine live in India (7.2 million children), Nigeria (3.1 million children), Indonesia (1.6 million children) and Ethiopia (1.2 million children). The other 9.3 million children live in many countries, but predominantly in Africa and South-East Asia.
There are many reasons why children are not fully vaccinated: the most important reasons include difficulty of access to health services, societal or community factors that prevent access to services, lack of vaccines, distribution systems or vaccine storage equipment and parental attitudes towards vaccine.
Are there plans in place to try to increase the DTP vaccination rates?
All countries of the world have subscribed to the Millennium Development Goals; one of these goals calls for the reduction of childhood mortality, and one of the most effective means to reduce mortality is vaccination.
The increase of vaccination coverage is a priority in many countries, and several strategies have been promoted to do this. In developing countries, the “RED”(Reaching Every District” strategy has been successful in increasing coverage, while in developed countries the close follow up of children due for their next vaccination, as well as school entry requirements of vaccination have been important factors.
Do you think the Millennium Development Goal 4 of reducing deaths among children under-five by two-thirds by 2015 compared to 1990 is achievable?
Yes, in general terms, although some countries do lag behind somewhat and may not be able to reach the goal in time. However, in almost all countries the mortality of children has been reduced through vaccination and several other public health initiatives, most notably the reduction of malaria with bednets and treatment, the provision of clean water and sanitation and the early treatment of common childhood diseases.
Would you like to make any further comments?
While DTP3 coverage is a very useful measurement to compare the performance of vaccination programmes across countries, and to highlight areas within countries that need further strengthening, to the individual child and to the country it is important to receive all scheduled vaccine doses. As such, the DTP3 coverage is just an interim measurement and the more important metric is the percentage of children that are fully immunized. Both for large scale disease control and eradication programmes and for the protection of each child personally their full vaccination with all scheduled vaccines is essential.
Where can readers find more information?
About Rudi Eggers
Dr. Rudi Eggers is a Public Health Specialist who has worked in the field of immunization for 18 years. Initially he was the Immunization Programme Manager in South Africa, then worked as the WHO Team Leader in support of the countries of Eastern Africa, based in Nairobi, and has since 2005 been the Team Leader in WHO HQ for the Immunization Services Strengthening team.