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Evidence summaries

Live Attenuated Varicella Vaccine for Healthy Children

Varicella vaccine is effective in reducing clinical chickenpox and varicella assosiated deaths in healthy children. Level of evidence: "A"

Trends in United States varicella mortality was assessed 2 using national vital statistics system data for 2008-2011, the first years of the routine 2-dose varicella vaccination program, and characteristics of varicella deaths reported to Centers for Disease Control and Prevention during 1996-2013 (table T1). Data on deaths with varicella as underlying or contributing cause was obtained from the 2008-2011 Mortality Multiple Cause-of Death records. The annual average age-adjusted mortality rate for varicella as the underlying cause was 0.05 per million population during 2008-2011, an 87% reduction from the prevaccine years. Varicella deaths among persons aged under 20 years declined by 99% in 2008-2011 compared with prevaccine years. There was a 70% decline in varicella mortality rates among those under 20 years in 2008-2011 compared to 2005-2007.

Annual Varicella-Related Deaths in the United States, 1990-2011

OutcomeVaricella listed as underlying cause of death
1990-19942005-20072008-2011
Total average no. of deaths per year1051517
Varicella listed as contributing cause of death
1990-19942005-20072008-2011
Total average no. of deaths per year39.620.316.3

A report evaluated 3 5 additional years of annual average mortality rate in the United States for varicella. Varicella death data from the 2012-2016 Mortality Multiple Cause-of Death records were used to calculate mortality rates during 2012-2016 and trends since the prevaccine period and end of 1-dose vaccination program (2005-2007). The annual average age-adjusted mortality rate for varicella as the underlying cause was 0.03 per million population during 2012-2016, a 94% reduction from prevaccine years and a 47% reduction from 2005-2007.

A topic in Clinical Evidence 1 summarizes the results of one systematic review including 2 placebo-controlled RCTs. The first RCT found that varicella vaccine reduced clinical chickenpox at 9 months (0/468 vs 38/446, ARR 8.5%, 95% CI 6.1% to 11.5%) and at 2 years (1/163 vs 21/161, OR 0.05, 95% CI 0.01 to 0.35). The second RCT found that varicalla vaccine reduced clinical chickenpox after a mean of 29 months (AR 5/166 vs 41/161, RR 0.12, 95% CI 0.05 to 0.29). Clinical Evidence category: Beneficial.

    References

    • Swingler G. What are the effects of interventions to prevent chickenpox in healthy adults and children? Clinical Evidence 2004;12:1053-1057.
    • Leung J, Bialek SR, Marin M. Trends in varicella mortality in the United States: Data from vital statistics and the national surveillance system. Hum Vaccin Immunother 2015;11(3):662-8. [PubMed]
    • Leung J, Marin M. Update on trends in varicella mortality during the varicella vaccine era, United States 1990-2016. Hum Vaccin Immunother 2018;1-11. [PubMed]

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