2008 recommended vaccination schedule; Paper on historical changes in disease rates

Last week's issue of MMWR included the recommended vaccine schedule for children and teenagers (i.e., birth to age 18). The familiar color-coded tables incorporate changes made in the joint recommendations of CDC, AAP, and AAFP over the past year. (The updated schedule was also published nearly simultaneously in the journal Pediatrics earlier this month.)

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Speaking of CDC, a paper by a group of researchers at its National Center for Immunization and Respiratory Diseases was published in JAMA in December titled, "Historical Comparisons of Morbidity and Mortality for Vaccine-Preventable Diseases in the United States."(free abstract; subscription required for full text). From the abstract, here is what the researchers report:

"A greater than 92% decline in cases and a 99% or greater decline in deaths due to diseases prevented by vaccines recommended before 1980 were shown for diphtheria, mumps, pertussis, and tetanus. Endemic transmission of poliovirus and measles and rubella viruses has been eliminated in the United States; smallpox has been eradicated worldwide. Declines were 80% or greater for cases and deaths of most vaccine-preventable diseases targeted since 1980 including hepatitis A, acute hepatitis B, Hib, and varicella. Declines in cases and deaths of invasive S pneumoniae were 34% and 25%, respectively."

A table showing this 'before-and-after vaccines' disease incidence data is a mainstay of Powerpoint presentations by vaccine policy-makers and researchers. While the numbers are impressive, such analyses of historical disease rates are fraught with challenges, particularly when attempting to isolate the impact of a certain variable (such as a vaccine) over many decades. To their credit, the authors of the paper note some of the many other factors that also contributed to the changes in disease rates during the 20th century, such as improvements in health care, standards of living, and many others.

The major decline in disease rates is impressive, and there's no doubt that vaccines play a major part in these successes. However, without being given comparisons to rates of other infectious diseases for which vaccines are not available, the reader of this paper could not be faulted for forgetting that vaccines are part of a much larger story of changes in medicine, health, and disease during the 20th century.