The purpose of the article by Glanz et al1 is to help clinicians counsel families and to encourage acceptance of the varicella vaccine. As a counselor and parent, I need to know the absolute risk, rather than the relative risk, of catching varicella if I refuse the vaccine. Approximately 1.6% of the almost 87 000 children in the Kaiser system do not get the vaccine because of parental refusal (10 children of 626 cases and controls); 5.26% of varicella disease was associated with vaccine refusal. Thus, 1390 children whose parents refused the vaccine (eg, “refusers”) were at risk and an estimated 16 refusers got varicella, for an attack rate of 1.17%. Similarly, the attack rate for children not vaccinated for reasons other than refusal (“acceptors”) is 0.34% (293 cases among 85 600 acceptors, a rate similar to the annual rate reported in Portland).2 Including children who were seen with a history of, but not active, varicella would represent a truer attack rate and estimation of resource consumption.
Harkavy K. Varicella Vaccine Refusal May Not Be Bad. Arch Pediatr Adolesc Med. 2010;164(8):780. doi:10.1001/archpediatrics.2010.132