Laxity in Vaccine Coverage May Repatriate Measles

Although endemic measles transmission has been eliminated thanks to vaccination efforts, outbreaks are nevertheless becoming increasingly common because of importation of the disease through international travel and a growing population of unvaccinated children in the United States. In the first half of 2008 (January through July), the number of reported cases of measles (131) was the highest year-to-date since 1996.¹

Measles is one of the first diseases to reemerge when rates of vaccination coverage decline (Figure). The current outbreaks may reflect a trend among parents to opt out of having their children vaccinated for either religious or philosophical reasons. Most of the cases reported between January 1 and July 31 occurred in school-aged children, and most (99, or 76%) were associated with cases characterized as importations. Of the 17 cases that were imported, 9 occurred in US citizens who had traveled abroad and 8 occurred in foreigners who had visited the United States. The source of 15 cases (11%) could not be determined.

Robust vaccination rates (greater than 90% for 1-dose coverage among preschoolers and greater than 95% for 2-dose coverage among school-aged children) are essential to maintain immunity against measles in the general population. Because measles is still common in Europe and elsewhere, 100% eradication in the United States would be unrealistic. Laxity in vaccination coverage and the resultant large numbers of unvaccinated persons in the community are perilous to public health. This trend is expected to worsen, leading to a return of endemic measles epidemics, unless vaccination coverage rates can be improved.

References:

REFERENCE:

1

. Centers for Disease Control and Prevention (CDC). Update: measles-United
States, January-July 2008.

MMWR.

2008;57:893-896.