Immunization is one of the most cost-effective interventions in public health and development. It helps individuals live longer, healthier and more productive lives. Through herd immunizations, vaccines protect the lives of those that are unvaccinated or under-vaccinated.
Herd immunization is a form of indirect protection from infectious disease that occurs when a large percentage of a population has become immune to an infection, thereby providing a measure of protection for individuals who are not immune.
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While the global vaccine coverage rate is 86%, countries with high vaccine coverage rates such as Canada skew the global average and in turn mask low vaccine coverage rates, particularly in low-income, fragile and conflict-affected countries. Some of the largest barriers to vaccine coverage are: 1) inaccessibility – lack of nearby clinics or an insufficient supply of vaccines in nearby clinics and, 2) unaffordability - many people cannot afford to take time off work to get vaccinated and/or afford the costs of the vaccines.
Another barrier to immunization is gender inequities. Women are more burdened by ill children and family members, more at risk of illness and infection, and experience poorer health and well-being over their lifespan. When women do not receive their vaccines, the negative health impacts are greater, can impede access to education and hinder ability to break out of cycles of poverty.
Key facts on immunization
- In 2018, 5.3 million children under the age of five died due to preventable illnesses and diseases. 
- Vaccines against measles, tetanus, whooping cough, diphtheria, and polio have saved more lives each year than world peace would have saved in the twentieth century.
- The HPV vaccine is the first cancer vaccine - it protects against around 90% of cervical cancers, and also provides protection against most of the genital cancers in men caused by HPV infection.
- Polio is on its way to being the second disease eradicated in history by vaccines (the first was smallpox). It remains endemic in only two countries: Afghanistan and Pakistan.
- Not all vaccines are given as shots. Some vaccines are given orally such as the live vaccination for typhoid.
- In Gavi-supported countries, for every US$1 spent on immunization, US$21 are saved in healthcare costs, lost wages, and lost productivity due to illness.