KD is an acute, inflammatory, small-to-medium sized vessel vasculitis manifest by prolonged high fever and some combination of rash, conjunctival suffusion, changes in the oral mucosa or peripheral extremities, and cervical lymphadenopathy; desquamation occurs in the convalescent phase, and ectasia or aneurysms can develop in the coronary arteries. An infectious etiology is suspected based on clustering of cases, but a genetic predisposition
is likely based on widely varying incidence in different racial and ethnic groups.

In June 2007 the label for RV5 was updated to include data regarding the occurrence of KD in Phase 3 clinical trials. The disease was reported within 42 days of vaccination in 5 of 36,150 vaccinees and 1 of 35,536 placebees, for an unadjusted RR of 4.9 (95% CI 0.6, 239.1). The wide confidence interval that includes 1.0 means that one cannot assume there is an association. Nevertheless this label change prompted renewed interest in the possibility that vaccine could trigger KD.

Early reassurance came from the VSD, where there had been only one unconfirmed case of KD within 30 days of 65,000 RV5 doses. A study published in 2009 provided further reassurance that RV5 was not a cause of KD. VAERS reports from 1990 through mid-2007 were analyzed, yielding only 97 cases. No clustering of cases was seen after vaccination. The reporting rates for KD in the 30 days following vaccination were 0.65 per 100,000 person-years before the RV5 label change and 2.78 per 100,000 person-years after the change; both rates were lower than the expected background incidence of 9 to 19 per 100,000 person-years.

—Marshall, Gary S. “Addressing Concerns About Vaccines.” The Vaccine Handbook: A Practical Guide for Clinicians. 3rd ed. New York: Professional Communications, Inc., 2010. 236. Print.

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