Vaccinations: what next?

In recognition of World Immunization Week, Dr Gary McLean reflects on the next steps for immunisation programmes.
Date: 25 April 2017

World Immunization Week is from 24 to 30 April 2017 and the theme this year for Europe is “vaccines work.” The week is a global public health drive aiming to raise awareness and promote more immunisation for known vaccine preventable diseases.

The incidence of many infectious diseases has decreased dramatically since the introduction of immunisation programmes, with the greatest success story being the eradication of smallpox as a human disease. However, there is still a long way to go to obtaining greater immunisation coverage, particularly for preventable diseases in resource-poor countries, for vaccine development for extremely variable pathogens (influenza, HIV) and emerging infectious diseases such as those caused by Coronavirus (MERS), Ebola and Zika viruses.

The World Health Organisation (WHO) lead World Immunization Week and state that; “vaccines work to protect individuals and communities, vaccines work to save lives, vaccines work to leave no one behind.”

There is a lot of conflicting information available on vaccines but there are 5 basic facts that everyone should be aware of regarding vaccines. According to the WHO:

  1. Vaccines are safe and effective
  2. Vaccines prevent deadly illnesses e.g. diphtheria, pertussis
  3. Vaccines provide better immunity than natural infections
  4. Combined vaccines are safe and beneficial e.g. measles mumps rubella (MMR)
  5. If we stop vaccination, diseases will return

History of immunisation

The practice of vaccination is hundreds of years old. The originator is often credited as Edward Jenner who, in 1796, used pus from a cowpox lesion to successfully inoculate a boy against the disease. Local folklore claimed that milkmaids, who often caught cowpox from their close contact with cows, never caught the far more dangerous smallpox. Jenner therefore speculated that exposure to cowpox led to immunity from smallpox. When the boy was exposed to the smallpox virus a few weeks later he showed no symptoms of the disease, proving Jenner’s theory to be correct.

Over the next two centuries the systematic immunisation programme led to the eradication of smallpox in 1979. The subsequent ability to weaken (attenuate) or inactivate bacteria or bacterial toxins allowed the development of cholera, anthrax, diphtheria, pertussis, and tetanus vaccines during the late 19th and mid-20th centuries.

More recently the improved ability to “grow” viruses in laboratories has led to the production of polio, influenza, measles, rotavirus, papillomavirus and hepatitis virus vaccines. This has led to 118 million children worldwide receiving basic vaccines every year. Numerous, once deadly, infectious diseases have now virtually disappeared from countries throughout the world.

The next steps in immunisation programmes

There is a need to immunise people in all regions of the world and at all stages of life.  When immunisation rates are high, entire communities are protected – this is a concept known as herd immunity. In this situation, even those few groups that are not immunised, such as the very young, the very old, or those with weakened immune systems, are protected through the immunity of “the herd” not allowing potential disease-causing pathogens to establish.

Thus, a major priority of immunisation campaigns is to stimulate greater vaccine uptake and better coverage into regions that are lacking in-depth immunisation programmes. Vaccine production also requires simplification without compromising safety, development costs need to be reduced so that new vaccines are made and provided more quickly, supplies of existing vaccines improved to isolated areas, and better education of communities to ensure that those who need vaccines are aware of it and that negative and unfounded publicity of immunisation disappointments is eliminated.

It is estimated that immunisation stops 2-3 million deaths each year but this number could be almost doubled if global vaccine coverage increases – it is thought that up to 20 million infants are not receiving basic vaccines and global vaccine coverage has remained stable for the past few years.

The majority of children not getting the key vaccines are from just 10 countries which require better access to vaccines and stronger links between immunisation programmes and existing healthcare services. Attempts are underway to have global vaccine coverage reach 90% by 2020 and the most recent target for eradication through immunisation is polio – just 3 countries remain where polio needs to be stopped. New vaccine development is slow despite huge pre-clinical efforts but the recent reported successes of an Ebola vaccine trial in West Africa shows that it can be done.

The signs are there that the elimination of vaccine preventable diseases through immunisation is achievable at a global level but who can predict what infectious menace is lurking around the corner. We just need to look at influenza to see how far we really must go to improve immunisation strategies.

Dr Gary McLean, Reader in Molecular Immunology, Cellular and Molecular Immunology Research Centre, School of Human Sciences at London Metropolitan University.

For more information or to request comment from Dr Gary McLean please contact Siobhan Pipa on s.pipa@londonmet.ac.uk.