Infectious Disease: Evolving Challenges to Human Health


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Making People Immune

As cases of a disease become rare due to vaccination, forgetfulness that the disease can still pose risks combined with concerns about vaccine safety can lead to complacency and vaccine avoidance. Diseases that are rare in one place may be common in other parts of the world and high speed travel means that diseases can spread rapidly. As individuals make decisions about whether to vaccinate themselves and their children, they must consider the risk of being non-immune to an infection that can be reintroduced at any time.

Two examples of diseases that people in the United States are regularly vaccinated against are measles and influenza.

Cases in the United States, 1950 – 1993

Graph of measles cases from 1950 through 1994

Cases of measles in the United States dropped dramatically after the licensing of the vaccine in 1963. There was a resurgence of measles in 1989-1991 resulting in 55,622 cases and 123 deaths. Many of these cases were in children under 5 years of age. This resurgence was due to low vaccination coverage.

Monthly Deaths from Pneumonia & Influenza in the United States

Graph of U.S.  Influenza and Pneumonia cases from 1910 to 2000

New influenza strains circulate around the world every year, and each strain may require a new vaccine. Occasionally, an entirely new strain arises to cause a pandemic, to which everyone is susceptible. In the last century there were pandemics in 1918, 1957, and 1968.

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