Vaccinations for Chickenpox Protects Infants As Well as Older Children
Chickenpox used to be one of the “classic” childhood diseases, but has become much less common since the introduction of the varicella vaccine. Because the disease is very contagious and easily spread to others, researchers have looked into the impacts of vaccinations beyond protection of just to whom they are given. Scientists from the CDC have discovered that the immunizing against varicella (chickenpox) does indeed protect other members of the family as well, including infants who are not yet eligible to receive the vaccination.
For those of us who remember chickenpox spreading through the schools when we were young, we may think “what’s the big deal?” However, infants who get chickenpox have an increased risk of developing serious complications such as pneumonia or a secondary skin infection. Last year in the United States, over 100 children died due to complications from the varicella-zoster virus.
Sandra Chavez MD and colleagues reviewed data collected both before and after the varicella vaccination program was implemented in the United States in 1995. Over 300 reporting units checked in every two weeks at active surveillance centers in Antelope Valley in Los Angeles (CA) county and West Philadelphia PA. In addition to information about identified varicella cases, a structured interview was also conducted with the parent/guardian to collect demographic and epidemiologic data.
Since 1995, there has been a “remarkable decline in varicella morbidity and mortality,” write the authors. Today, the incidence of chickenpox among infants is 89.7% lower than it was in the mid-90’s – a drop from 15.6 cases per 1,000 infants to 1.6 per 1,000. In addition, those infants 5 months and younger who do contract the virus are generally having milder disease (ie: fewer lesions).
The authors conclude that the varicella vaccination program has resulted in substantial direct and indirect benefits. Improving coverage in all age groups would like result in even better protection, particularly for those who aren’t eligible to receive the vaccine. Women who have received the vaccine later pass on the protection to their infants as well through antibodies produced to fight the virus.
Most cases of chickenpox occur in children between the ages of 1 and 10. Before the appearance of the characteristic itchy, blister-covered rash, children often experience fever, headache, and stomach ache. The virus is contagious even at this point, because it is airborne.
The varicella vaccine is an attenuated (live but weakened) virus that protects the patients specifically from the Varicella Zoster virus (VZB). In the US, the vaccine is called Varivax and manufactured and marketed by Merck. Forty-one states currently require that a child be vaccinated against chickenpox before attending a state-run elementary school.
Chaves SS, et al "Varicella in infants after implementation of the U.S. varicella vaccination program" Pediatrics 2011; 128: 1071-1077.