For people who haven't had chickenpox and are exposed to an ill family member, getting vaccinated within five days can reduce the risk of developing chickenpox—or at least reduce the severity of disease, reports a study in the January issue of the Pediatric Infectious Disease Journal.
"Available varicella vaccines administered within five days after exposure to chickenpox are effective in preventing chickenpox and highly effective in attenuating the disease," concludes the study by Dr. Maria Brotons and colleagues of Hospital Universitario Vall d'Hebron, Barcelona.
The researchers analyzed their experience with "post-exposure prophylaxis"—giving chickenpox (varicella) vaccine after exposure to the disease—in 67 patients. The patients, including 21 children, were exposed to a family member with chickenpox. All patients received commercially available chickenpox vaccine within five days after exposure, most within three days.
Because they had not had chickenpox or received the chickenpox vaccine, the patients were at high risk of developing chickenpox. Their lack of immunity was confirmed by serologic studies. Based on past studies, it was estimated that 58 of the 67 patients would get sick after being exposed to chickenpox. However, only 22 patients developed disease after being vaccinated. Thus vaccination after exposure was about 62 percent effective in preventing chickenpox.
