Vaccinating children against varicella: are two doses of vaccine necessary? Varicella is a mild childhood disease. Serious complications are rare and more common in infants, adults and persons with weakened immunity. Varicella vaccine has been available for a long time. In 1998, the World Health Organization recommended universal varicella vaccination with only one dose. Later it has been shown that vaccination with two doses of varicella vaccine is more immunogenic compared to one dose. A lack of protective effectiveness has been found with a single dose only. Consequently, some countries with universal varicella vaccination for children switched to a two-dose vaccination. A systematic review of the published studies on the effectiveness of vaccination supporting the rationale for introducing a second dose of varicella vaccine was made. A few studies show that vaccination with two doses in children is more effective than vaccination with one dose. Also our position is to recommend that children be vaccinated with two doses, because the possibility of infection is still significant due to the intensive circulation of causative agent. PUBLICATION ABSTRACT