Introduction to Vaccine-Preventable Diseases in Children and Adolescents

Geographic Distribution and Epidemiological Trends

Worldwide in 2018, the percentage of children immunized with three doses of diphtheria, tetanus, and pertussis (DTP) and oral polio vaccines, and a measles-containing vaccine exceeds 85%. Although vaccines have proven safe and cost-effective, saving $16.00 in healthcare costs, lost wages, and lost productivity due to illness and death for every dollar spent, many developing countries do not have adequate and consistent access to available or affordable vaccines, particularly for newer vaccine products, some of which have narrow geographic use, such as protein-conjugate pneumococcal, typhoid, and meningococcal vaccines, and Japanese encephalitis.

During the time period of 2016 to 2018, the immunization coverage rate in the United States at age 24 months with the full seven-vaccine series (4:3:1:3:3:1:4 series): four diphtheria toxoid and tetanus toxoid with acellular pertussis vaccine (DTaP); three polio; one measles, mumps, rubella vaccine (MMR); three (or four) Haemophilus influenzae type b vaccine [Hib]; three hepatitis B, one varicella, and four pneumococcal conjugate vaccines was only 68.5%. However, coverage rates exceeded 90% for polio, MMR, hepatitis B, and, varicella on an individual vaccine basis. Although only 1.3% of children had received no vaccines, vaccine coverage in the United States varies widely based on both geography and family demographics. Low vaccine coverage is associated with lack of private health insurance, poverty, and being of the Black or American Indian/Alaska Native race. Twenty states have MMR coverage less than 90%, with pockets in some communities significantly lower. In many of these localities, parental reluctance to vaccinate and acceptance by local governance of nonmedical exemptions to vaccine requirements are highly prevalent, putting them at risk for outbreaks of vaccine-preventable diseases, as represented by the more than 1200 measles cases that occurred nationwide in 2019. Vaccine hesitancy is an emerging problem for the United States and other industrialized nations that historically have had high coverage rates and had eliminated many of these diseases, only to see reemergence of the diseases with decreasing coverage. Engaging parents reluctant to vaccinate requires careful consideration of the underlying concerns and a thoughtful communication strategy, preferably from a trusted source.

General Principles