Scientific Success Story—Varicella (Chickenpox)

Chicken is usually considered a childhood disease. Something that most of us have suffered through. Caused by the Varicella-zoster virus, chickenpox and in unvaccinated populations, spreads by direct contact or through coughing or sneezing.

Chickenpox most commonly causes an illness that lasts about 5-10 days. Children usually miss 5 or 6 days of school or childcare due to their chickenpox and have symptoms such as high fever, severe itching, an uncomfortable rash, and dehydration or headache. In addition, about 1 in 10 unvaccinated children who get the disease will have a complication from chickenpox serious enough to visit a health-care provider. These complications include infected skin lesions, other infections, dehydration from vomiting or diarrhea, or more serious complications such as pneumonia and encephalitis.

Before the vaccine was available, over 10,000 people in the US were hospitalized and between 100 and 150 died.

A recent study published online in the journal Pediatrics, Near Elimination of Varicella Deaths in the US After Implementation of the Vaccination Program discusses exactly what the title says.

ABSTRACT

OBJECTIVE: Varicella has been preventable by vaccination in the Unted States since 1995. Previous studies reported a 66% decline in mortality rate during the first 6 years of the program. Since then, vaccination coverage has increased substantially. We updated the analysis of US varicella mortality for 2002–2007 and assessed the imact of the first 12 years of the US varicella vaccination program on varicella deaths.

METHODS: National data on deaths for which varicella was listed as an underlying or contributing cause were obtained from the Mortality Multiple Cause-of-Death records from the US National Center for Health Statistics. We calculated the age-adjusted and age-specific mortality rates for 2002–2007 and trends since the prevaccine years.

RESULTS: During the 12 years of the mostly 1-dose US varicella vaccination program, the annual average mortality rate for varicella listed as the underlying cause declined 88%, from 0.41 per million population in 1990 –1994 to 0.05 per million population in 2005–2007. The decline occurred in all age groups, and there was an extremely high reduction among children and adolescents younger than 20 years (97%) and among subjects younger than 50 years overall (96%). In the last 6 years analyzed (2002–2007), a total of 3 deaths per age range were reported among children aged 1 to 4 and 5 to 9 years, compared with an annual average of 13 and 16 deaths, respectively, during the prevaccine years.

CONCLUSIONS: The impressive decline in varicella deaths can be directly attributed to successful implementation of the 1-dose vaccination program. With the current 2-dose program, there is potential that these most severe outcomes of a vaccine-preventable disease could be eliminated.

A picture is worth 1,000 words, and here is a graph from the paper.

Varicella Deaths

 

In Canada, the story is pretty much the same.

The number of chickenpox-related hospitalizations has dropped 84% in provinces that adopted the CPS’s recommendations between 2000 and 2002, and 65% for those that started between 2004 and 2006.

The Canadian Paediatric Society is now recommending a second shot of the Varicella vaccine for children 4-6 years old, as a follow up to their initial shot at 12-18 months.

The CPS recommends that everyone get the vaccines with the fllowing exceptions:

  • Babies less than 1 year old.
  • People with weak immune systems and/or people who are taking drugs to suppress their immune system.
  • Women who are trying to get pregnant. However, if you get the vaccine before you know you are pregnant, your baby will almost certainly be fine.
  • People who are allergic to or have had a bad reaction to something in the vaccine.
  • People who have had chickenpox after they are 1 year of age do not need to get the vaccine. They are most likely immune to the illness now. If they do get the vaccine, it will not hurt them.

Many people continue to think of chicken pox as relatively harmless. However, for anyone who has lost a child, or had a child suffer serious complications toward in this is great news and a major step forward in paediatric care.

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One Response to Scientific Success Story—Varicella (Chickenpox)

  1. Pingback: Cosmetic Acupuncture | PEI Curmudgeon's Blog

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