INTRODUCTION
Vaccines can be defined as biological preparations that stimulate the immune system to provide protection against specific diseases. Vaccines have been instrumental in preventing and controlling numerous infectious diseases over the past century (1). They have saved countless lives and significantly improved global public health. The following highlights the importance of vaccines in combating infectious diseases and the significant impact they have had on global health:
Smallpox:
Smallpox, caused by the variola virus, was a devastating disease until it was officially declared eradicated in 1980, thanks to a global vaccination campaign led by the World Health Organization (WHO). The smallpox vaccine, developed by Edward Jenner in the late 18th century, played a crucial role in eliminating this highly contagious and deadly disease (1). In West Africa, where smallpox was once endemic, the introduction of mass vaccination campaigns led to the elimination of the disease and redirected healthcare resources to other public health priorities (1).
Polio:
Polio, caused by the poliovirus, once paralyzed thousands of children annually. The development of effective polio vaccines, such as the inactivated polio vaccine (IPV) and oral polio vaccine (OPV), has led to a significant reduction in polio cases worldwide. Nigeria, the last African country to report polio cases, has remained polio-free since 2020 due to sustained immunization efforts 10. Global efforts, such as those by the Global Polio Eradication Initiative, have brought us closer to eradicating polio altogether (2).
Measles:
Measles, a highly contagious viral disease, can lead to severe complications, including pneumonia and encephalitis. Vaccination against measles has been highly effective in preventing outbreaks and reducing the global burden of the disease. The measles-mumps-rubella (MMR) vaccine has played a crucial role in controlling measles, with high vaccine coverage leading to a substantial decline in cases (3).
Rubella:
Rubella, also known as German measles, can cause serious birth defects if a pregnant woman becomes infected. The combined MMR vaccine provides protection against rubella, among other diseases, and has contributed to a significant reduction in rubella cases worldwide (4). The development of the rubella vaccine has been crucial in preventing congenital rubella syndrome.
Diphtheria:
Diphtheria, a bacterial infection that can affect the respiratory tract and skin, was a major cause of death in children before the development of the diphtheria vaccine. Vaccination against diphtheria, typically administered as a component of the diphtheria-tetanus-pertussis (DTP) vaccine, has been highly effective in preventing the disease. Routine immunization programs have significantly reduced the global burden of diphtheria (5). In Morocco, for instance, the implementation of a comprehensive vaccination strategy resulted in the elimination of diphtheria cases since 1999 (5).
Tetanus:
Tetanus, caused by the bacterium Clostridium tetani, is a life-threatening disease characterized by severe muscle stiffness. Vaccination against tetanus, usually administered as part of the DTP vaccine, has been instrumental in preventing tetanus infection. Adequate immunization coverage has drastically reduced the number of tetanus cases globally (6). In Nigeria, the introduction of tetanus toxoid vaccination for pregnant women has led to a substantial decline in neonatal tetanus cases and associated deaths (6).
Pertussis:
Pertussis, commonly known as whooping cough, is a highly contagious respiratory disease. Vaccination with the DTP vaccine has been effective in preventing pertussis and its complications. However, waning immunity and the emergence of new strains have highlighted the importance of booster doses and maintaining high vaccination coverage to control pertussis outbreaks (7). In Uganda, the expansion of pertussis vaccination coverage has resulted in a significant reduction in pertussis-related hospitalizations and deaths among infants (7).
Hepatitis B:
Hepatitis B is a viral infection that can cause chronic liver disease and liver cancer. Vaccination against hepatitis B has been highly successful in preventing new infections. The hepatitis B vaccine, usually administered as a series of doses, has significantly reduced the global burden of hepatitis B and its associated complications 8. In Gambia, the introduction of hepatitis B vaccination for infants has led to a significant decline in chronic hepatitis B infection rates among children (8).
Haemophilus influenzae type b (Hib):
Hib is a bacterial infection that can cause severe illnesses, including meningitis and pneumonia, primarily affecting young children. The development and widespread use of the Hib vaccine have dramatically reduced the incidence of Hib-related diseases. Routine immunization programs have led to a significant decline in Hib cases globally (9). For example, in The Gambia, the implementation of Hib vaccination led to a 90% decline in Hib meningitis cases among children under five years old (11).
CONCLUSION
These fast facts underscore the tremendous impact vaccines have had on global public health by preventing millions of deaths and improving the well-being of countless individuals. Continued efforts to develop and administer effective vaccines are essential to further protect against existing and emerging infectious diseases (1). Looking ahead, it is crucial to continue investing in research and development to expand vaccination coverage for diseases that currently lack vaccines. This includes diseases such as malaria, HIV/AIDS, and dengue fever, where the development of safe and effective vaccines would have a transformative impact on public health in Africa and around the world.
REFERENCES
1. Fenner F, Henderson DA, Arita I, Jezek Z, Ladnyi ID. Smallpox and its eradication. Geneva: World Health Organization; 1988.
2. Global Polio Eradication Initiative. Polio Eradication & Endgame Strategic Plan 2019-2023. Geneva: World Health Organization; 2019.
3. World Health Organization. Measles. [Internet]. 2021 [cited 2023 May 20]. Available from: https://www.who.int/news-room/fact-sheets/detail/measles
4. World Health Organization. Rubella. [Internet]. 2021 [cited 2023 May 20]. Available from: https://www.who.int/news-room/fact-sheets/detail/rubella
5. Centers for Disease Control and Prevention. Diphtheria. [Internet]. 2020 [cited 2023 May 20]. Available from: https://www.cdc.gov/diphtheria/index.html
6. World Health Organization. Tetanus. [Internet]. 2021 [cited 2023 May 20]. Available from: https://www.who.int/news-room/fact-sheets/detail/tetanus
7. Centers for Disease Control and Prevention. Pertussis (Whooping Cough). [Internet]. 2022 [cited 2023 May 20]. Available from: https://www.cdc.gov/pertussis/index.html
8. World Health Organization. Hepatitis B. [Internet]. 2021 [cited 2023 May 20]. Available from: https://www.who.int/news-room/fact-sheets/detail/hepatitis-b
9. World Health Organization. Haemophilus influenzae type b (Hib). [Internet]. 2021 [cited 2023 May 20]. Available from: https://www.who.int/teams/health-product-policy-and-standards/standards-and-specifications/vaccine-standardization/hib
10. Global Polio Eradication Initiative. Polio Eradication & Endgame Strategic Plan 2019-2023. Geneva: World Health Organization; 2019. https://apps.who.int/iris/handle/10665/329948
11. World Health Organization. Haemophilus influenzae type b (Hib) vaccination. [Internet]. 2021 [cited 2023 May 20]. Available from: https://www.who.int/teams/health-product-and-policy-standards/standards-and-specifications/vaccines-quality/haemophilus-influenzae
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