A bout of chickenpox may seem preferable to vaccination, but not if your child ends up in hospital.
“I bet he wasn’t the one at home taking care of nine sick kids,” scoffed one woman in response to a Washington Post story about Bevin’s opposition to vaccination and his support for chickenpox parties (deliberately exposing your children to a child with an active infection).
As anyone who has looked after a child with chickenpox knows, it can be a miserable – and time-consuming – experience for both child and parent.
About 55,000 New Zealand children get chickenpox each year. Some have only a few poxes – fluid-filled, blister-like sores that eventually burst and release their virus-containing liquid. But most get many more, and sometimes their body is covered, including inside their mouth, on their eyelids and around their genitals.
About 450 children are hospitalised each year because of complications caused by chickenpox. Some, such as viral pneumonia, are caused by the virus itself. But children are more likely to be admitted to hospital because of secondary bacterial infections that enter through the burst poxes.
A small number of them die. According to University of Auckland vaccinologist Helen Petousis-Harris, 26 children were treated in Starship Hospital’s intensive care unit between 2001 and 2011 for complications caused by chickenpox. Of those, eight left disabled and four died.
“Chickenpox can be more serious for people with underlying conditions, such as a suppressed immune system, but it’s important to remember that most of those who end up in hospital were previously healthy.”
Petousis-Harris is looking forward to seeing a big drop in the number of hospitalisations and deaths now that we’ve added chickenpox to our childhood immunisation schedule. In July 2017, children started receiving the chickenpox vaccination at 15 months, along with measles, mumps, rubella (MMR) and several other vaccinations.
That means most children born since early 2016 will never have chickenpox, which Petousis-Harris regards as a very good thing. Although chickenpox is not as serious as measles, the vaccine was developed for good reasons. “People don’t bother to make a vaccine if there’s no health need or a public-health or cost benefit.”
It will take several years for the chickenpox virus to stop circulating, and most older, unvaccinated children will continue to get it naturally.
However, Petousis-Harris has no time for “chickenpox parties”. She says it’s better to avoid the potential risks of chickenpox by paying $80 to have older children vaccinated – or taking advantage of the free vaccination now available to 11-year-olds who have not had the illness.
Getting rid of chickenpox has another long-term benefit: reducing the incidence of shingles, a painful skin rash that can cause long-term damage such as vision loss. Shingles affects people who have previously had chickenpox; the virus lies dormant in their nervous system for many years, then “wakes up” when their immunity wanes in older age.
Although it’s possible for the weakened version of the live virus used in the chickenpox vaccine to reactivate, this is thought to be rare. That means vaccinated children are much less likely than previous generations to develop shingles later in life.
However, there are concerns that vaccinating children against chickenpox will cause a temporary increase in shingles. According to what’s known as the exogenous boosting theory, being exposed to children with chickenpox boosts immunity levels in previously infected adults. This helps protect them from getting shingles as they get older.
Those who support this theory – including the British National Health Service, which has not yet introduced a free chickenpox vaccination – worry that as the number of children with chickenpox starts falling, many people will be deprived of the chance to boost their immunity, making them more susceptible to shingles.
But Petousis-Harris says there’s growing evidence this will not happen. For a start, shingles rates are increasing in all countries, regardless of whether they vaccinate against chickenpox or not. And she says it now seems more likely that people who were infected as children effectively “self-boost” their immunity in response to such things as stress.
“There’s a school of thought that boosting comes from within.”
This article was first published in the April 20, 2019 issue of the New Zealand Listener.