Varicella vaccine for susceptible adults: do it today.

At the time of the varicella outbreak among immigrant workers at a poultry processing factory and at their apartment complex, reported in this issue of Clinical Infectious Diseases [1], live attenuated var-icella vaccine had been licensed for routine use in the United States for 5 years [2]. Nevertheless, these highly varicella-susceptible young adults, most of whom had been born in Mexico or Central America, were not immunized, and 28% of those who were infected developed severe cases of varicella with complications, some of which required hospitalization. Fortunately, there were no fatalities from this preventable illness. Varicella outbreaks such as this one should no longer occur in the United States. An effective vaccine that is highly protective against varicella— and especially protective against severe cases of varicella—and that has decreased hospitalizations and deaths from this infection is widely available and should be universally used [3]. There is all the more reason to immunize varicella-susceptible adults because, as this study [1] well illustrates , adults are at higher risk to develop severe cases of varicella than are children. In a previous study [4], adults with varicella were 25 times more likely to develop severe cases than were children with varicella. Current controversies regarding vari-cella vaccine include whether a second dose should be required to boost immunity in children. It is possible that routine administration of 2 doses of vaccine to children will better prevent outbreaks of mild to moderate disease among the vaccinated population and provide more lasting immunity than administration of a single dose. The second controversial issue is whether widespread use of varicella vaccine will increase rates of infection with varicella zoster virus (VZV) among those who have experienced varicella caused by wild-type strains [3]. Immunization of varicella-susceptible adults, however, is not controversial and should be a priority, because wild-type strains of VZV continue to circulate in our country, and varicella-susceptible adults are at risk to be exposed to this highly contagious virus. One might predict that hospital personnel, students and other young adults living in dormitories or other crowded conditions, and teachers are at particular risk if they remain susceptible to varicella. Despite the need to vaccinate adults, however, there are some obstacles. These include the lack of availability of a reliable, inexpensive serological test to determine susceptibility to varicella and to document an immune response to the vaccine; the lack of a unified strategy to identify and vaccinate …