Varicella vaccine effectiveness – more supporting evidence

The varicella vaccination for chickenpox was introduced in the mid-1990’s in the USA and has been associated with substantial and statistically significant declines in incidencehospitalizations and deaths attributable to chickenpox. Thanks to  real science, more evidence supports varicella vaccine effectiveness.

Despite the beliefs of vaccine refusers, who have stated emphatically that chickenpox is not dangerous, the real complications from a varicella infection are numerous and serious:

  • dehydration
  • pneumonia
  • bleeding problems
  • infection or inflammation of the brain (encephalitis, cerebellar ataxia)
  • bacterial infections of the skin and soft tissues in children including Group A streptococcal infections
  • blood stream infections (sepsis)
  • toxic shock syndrome
  • bone infections
  • joint infections

Since I was born before the chicken pox vaccine, I contracted the disease, which eventually lead to encephalitis. I have vivid memories of being a five year old child and being admitted into the ER with a brain infection. It’s a memory I’d rather not have.

The anti-vaccine gang love to question the effectiveness of vaccines. But they don’t have evidence of that, whereas, I’m going to present some powerful evidence that the varicella vaccine is highly effective in preventing chickenpox.

Varicella vaccine effectiveness

 

In a recent article published in Pediatrics by Dana Perella et al., the researchers studied the effectiveness of the 2-dose varicella vaccine regime in preventing community transmission of chickenpox amongst children aged 4-18. From May 2009 to June 2011, chickenpox cases identified in Antelope Valley, CA (near Los Angeles) and Philadelphia, PA were enrolled into a matched case-control study.

A case-control study is a type of epidemiological investigation in which two groups with differing outcomes (in this case, with and without chickenpox) are compared on some causal attribute, in this case, vaccination. The “cases” are the children who contracted chickenpox, and the “controls” are the children, matched in age and other factors with the cases, who do not have chickenpox.

The researchers examined 125 clinically diagnosed varicella cases against 408 matched controls.

Here’s what they found:

  • After one dose, the vaccine effectiveness (VE) was 75.6% in preventing moderate or severe chickenpox.
  • After two doses (the recommended schedule), VE was 93.6% against all types of varicella infection.
  • Moreover, after two doses, the VE was 97.9% against moderate or severe chickenpox.

This data provides the reason why in 2010, Antelope Valley and Philadelphia reported >60% 2-dosce varicella vaccination coverage among 5 year old children, which lead to a 67-78% reductions in overall chickenpox incidence since 2006. And no, there wasn’t a sudden improvement in the sanitation or healthcare systems since 2006.

Summary

 

The authors concluded that:

[infobox icon=”quote-left”]Two-dose varicella vaccination improved protection against community transmission of varicella among school-aged children in 2 geographically and demographically diverse areas compared with 1-dose vaccination. Our study provides more direct evidence on the protective effect of a 2-dose varicella vaccine regimen.[/infobox]

The chickenpox vaccine works. And it saves lives.

 

Key citations

 

The Original Skeptical Raptor
Chief Executive Officer at SkepticalRaptor
Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!