Looming Large: The Cost of Not Vaccinating

By bmartin on May 9, 2008 10:21 AM | Permalink | Comments (1) | TrackBacks (0)

2008 is becoming the year of reckoning, thanks in part to the anti-vax movement. Today's MMWR reveals that 64 cases of measles—a disease declared eliminated in the United States in 2000—have occurred so far this year in the country.* Compare that number with the average 62 cases annually during the last 8 years, and you've got the expectation for a dubious record in 2008.

According to the MMWR, most reported measles cases (84%) this year were due to imported disease from other countries (59 patients were US residents), and the overwhelming majority occurred in persons who were unvaccinated or whose vaccination status was unknown. Exactly half of the patients were younger than 5 years; 14 were younger than 1 year and therefore not eligible for immunization. Among the 21 US residents aged 16 months to 19 years, two thirds claimed exemption from vaccination because of religious or personal beliefs. Twenty-one measles patients were adults (including 1 US resident born before 1957).

Although 14 (22%) of those affected were hospitalized, there were no fatalities. Possibly the most shocking revelation is that 1 patient was an unvaccinated health care worker who acquired the disease in hospital. Another 17 individuals were infected while visiting a health care facility, including a 12-month-old child who, ironically, was exposed to the virus in the physician's office while receiving a routine MMR vaccine.

Details of the 2008 measles cases are tabulated below, and the MMWR provides a very nice annotated map:

Location	No. Cases	Date of Cases/ Outbreak	Source
San Diego, CA	11	01/25-02/16	Switzerland; genotype D5 (Index pt = unvaccinated child who traveled to Switzerland)
Honolulu, HI	3	02/05-02/25	California outbreak (1), Italy (2)
NY, NY	22	02/07-04/20	Israel (2), Belgium (2), Unknown (8); genotype D4
Pima Co, AZ	15	02/13-04/23	Switzerland; genotype D5 (Index pt = unvaccinated adult from Switzerland)
Missaukee Co, MI	4	02/19-04/08	Unknown; genotype D5 (Index pt = unvaccinated 13-year-old)
Fairfax, VA	1	02/25	India
Milwaukee Co, WI	4	03/19-04/09	China (likely); genotype H1 (Index pt = 37-year-old with unknown vaccination status; likely exposed to Chinese visitor with disease)
Los Angeles, CA	1	03/23	Unknown
Pittsburgh, PA	1	04/12	Unknown
Nassau Co, NY	1	04/12	Unknown
Chicago, IL	1	04/17	Switzerland

Although US vaccination levels are high, reports the MMWR, unvaccinated children tend to be clustered geographically or socially, which increases the risk of outbreaks. The article undermines the belief of some vaccine rejectionists that they can coast on the vaccine-provided immunity of other US residents. Cases to date show that the risk of imported disease remains high, and that unvaccinated individuals can propagate the spread of foreign-born infection. It is notable that a substantial measles outbreak occurred earlier this year in San Diego, CA, home of 3 vaccine-rejecting moms who were recently profiled by the NYT. The index patient in the San Diego outbreak was an unvaccinated child, who brought the infection back from Switzerland.

And California receives more negative attention today because of a pertussis outbreak that has closed a private school near San Francisco.

*Up until April 25.