Double varicella dose for chickenpox

Two doses of varicella vaccine are more effective than one to prevent chickenpox in children, a US study shows.

Since 2006, the US Centers for Disease Control and Prevention has recommended a second dose of varicella vaccine be routinely administered to children aged 4–6.

Researchers assessed the effectiveness of two doses of varicella by comparing 71 cases of confirmed varicella with 140 controls matched by age and paediatric practice.

They found that two doses of the vaccine was 98.3% effective in preventing chickenpox, compared with one dose, which was 86.0% effective. 

In the first two years after the introduction of the second dose, the odds of developing chickenpox for children who had received two doses of vaccine were 95% lower than for those who received one dose.

Only one dose of varicella vaccine for children is included in the Australian National Immunisation Program schedule.

However, The