Do vaccines save lives? Yes they do!

Since their introduction and widespread use, vaccines have been very successful in reducing morbidity and mortality of the diseases they target, at an individual level and through herd immunity. The impact on the mortality has been rapid and easy to measure for some diseases, such as diphtheria, pertussis and measles. For other diseases, including hepatitis B and human papillomavirus infections, deaths averted occur many years after vaccination, and it takes years until the full potential of the vaccine can be established. Finally, in middle and high income countries, the impact of vaccination against some diseases, like invasive pneumococcal disease and rotavirus gastro-enteritis, is measured by decrease in incidence of the disease and reduction in hospitalization rather than impact on mortality. But in the countries with the highest incidence of these diseases, mortality remains high due to low availability of these vaccines, and millions of deaths could be averted by optimal use of vaccines in these regions. Major challenges for vaccination programmes are to maintain and strengthen trust in the benefits of vaccination and adapt immunization schedules according to the changing epidemiological landscape.