We have had a vaccine against varicella (chickenpox) for over 15 years now. A recent study in the journal Pediatrics assessed how well it has worked at one of its major jobs — preventing death from chickenpox. Just have a look at this graph, taken from the article. It breaks down chickenpox deaths into those in which it was the direct cause and those in which it was a contributing cause.
Many parents, and certainly virtually all grandparents, would be startled by my title. Deaths from chickenpox? Isn’t getting chickenpox just an ordinary part of childhood? Well, until recently it was. A fair number of parents still think it should be, deliberately exposing their child to active cases in the hope (expectation, really) that their child will contract a mild case and then be immune for life. I’ve also heard parents say that the “natural” chickenpox is more protective than the vaccine is. There is some truth in this if your child only gets one vaccination. However, a booster shot later gives a child the same degree of protection as the natural illness. You can get a good view of that discussion over at Dr. Wendy Swanson’s blog, SeattleMamaDoc. Here is what Dr. Paul Offit, noted vaccine expert at Children’s Hospital of Philadelphia, has to say about this.
Chickenpox deaths were rare even before the vaccine. But they happened. Before I went into critical care I practiced the subspecialty pediatric infectious diseases, and I saw several. Children who had abnormal immune systems, especially from cancer treatment, were particularly susceptible. Eradicating chickenpox from the population protects these vulnerable children because chickenpox is one of the most highly infectious diseases known, with an attack rate of well over 90%. The majority of severe cases, however, were still in otherwise normal children.
The graph is dramatic, but if you look at the numbers you will see that even before the vaccine we only had about 1 death per million children or so — that’s a lower risk than driving on the interstate. But deaths were only the tip of the iceberg. Chickenpox also led to a large number of hospitalizations (and severe disease) from secondary infection of the pox sores. You can well imagine how skin bacteria could take advantage of so many breaks in the skin to crawl in and cause trouble. The most notorious for doing this was Staphylcoccus aureus (aka staph), but others could do it as well.