Are Chickenpox Parties Safer Than Vaccines? Absolutely not. Here's Why | Opinion

There is a debate raging in the United States about "chickenpox parties." The debate was prompted by the Kentucky Governor Matt Bevin admitting, in a radio interview, that he had deliberately exposed his 9 children to others in his neighborhood with the disease, so that they became infected naturally rather than receive the chickenpox vaccine. It is another example of confused thinking about the science of disease and its prevention.

The chickenpox (varicella) vaccine is currently available in the United States for all children in a 2 dose schedule (first dose in the second year of life and second dose at 4-6 years of age.) In the US, prior to the introduction of chickenpox vaccine from 1995, there were around 4 million cases per year, up to 13,000 hospitalizations and 150 deaths. Since vaccine introduction cases have fallen by almost 90 percent, and almost all hospitalizations and deaths have gone.

The numbers need no explanation, and clearly show why doctors are in favor of preventing the disease. It is true that for most children, chickenpox is a really unpleasant, but self-limiting disease. It causes misery through the fever and itchy rash and is a big burden on society as parents will usually miss 5-7 days of work caring for the child. But it is clear from the figures from the US, prior to vaccine introduction, that not all cases are on this milder end of the spectrum.

In unvaccinated children, the chickenpox virus itself causes some of the hospitalizations and deaths as a result of serious complications such as viral pneumonia (lung infection) or encephalitis (brain infection.) Individuals whose immune system is compromised are at particular risk of chickenpox, especially newborns, pregnant women, children (and adults) who are receiving chemotherapy to treat cancer, those who have a genetic defect in their immunity or are infected with HIV.

There are also very serious complications caused by bacteria: the virus damages the skin and internal surfaces of the throat through the formation of the typical rash (the "pox" in chickenpox) causing a breach in the main physical barrier that prevents bacteria getting into the skin or bloodstream. In chickenpox, bacterial infection of the skin or dissemination of the bacteria through the blood leads to serious bacterial complications including infections in skin (necrotizing fasciitis,) muscles, bones and joints or widespread disease such as life-threatening sepsis.

These "secondary" bacterial infections are the major cause of hospitalisations and the deaths discussed above. Vaccination against chickenpox protects the vaccinated child from all of these serious complications of the disease, and also stops them spreading the virus to children who cannot be vaccinated (such as those with cancer mentioned above.) In a society where vaccination is available and can be used to effectively protect one's own children from a disease which could kill them, and potentially prevent transmission to other vulnerable children in the neighborhood with cancer, surely there is a moral obligation to do so?

Since almost everyone will get chickenpox during childhood, it follows that anyone in the US deciding not to vaccinate their children should weigh up the risks of the disease, outlined above, with the risks of the vaccine. Here there is no competition, there are very real risks of the disease as we have discussed if allowed to happen naturally, which is contrasted with a vaccine with an extraordinary safety record. The vaccine is made from a live weakened strain of the chickenpox virus and so it can cause a mild form of the disease and so some individuals will have a short-lived fever and, in some cases, a few chickenpox spots (and a sore arm like with most vaccines). Because the vaccine virus is weakened, any symptoms will be milder than would be the case with the wild infection, and in practice significant complications are vanishingly unlikely. So the choice is a infection with a wild uncontrolled natural virus or a vaccination with a weakened strain of the same virus. Not a difficult choice.

In the United Kingdom, the vaccine is currently only available on the private market and is not part of our routine program. The scientific debate on the use of chickenpox vaccine introduction in the National Health Service (NHS) immunization program, is not about whether the vaccine works, whether it would prevent hospitalizations and deaths in childhood or whether it is safe. None of these are in any doubt. In a slightly confusing twist to the story, the debate centres around shingles in the elderly.

We know that shingles, which can be a painful skin disease in the elderly, is caused by the same chickenpox virus that individuals with the condition caught as children. The chickenpox virus lies dormant in our nervous system throughout life, and then awakes as our immunity wanes in old age, to reappear as shingles. The current models suggest that exposure as adults to young children with chickenpox should boost an adult's immunity and reduce the rate of shingles in the elderly, saving money for the NHS. If the vaccine is used for children, there is a theoretical risk that elderly shingles rates could increase, at least for a generation (i.e. until vaccinated children age into the elderly category), as the vaccine would prevent disease in children and at the same time reduce opportunities for adults to be boosted.

While a childhood programme in the UK would likely be cost-effective for the NHS, this would not be the case if it had the consequence of affecting shingles rates in the elderly, and an introduction here has stalled on this technicality. So far, there hasn't been an increase in shingles in the US which could be attributed to their childhood programme. Review of emerging evidence continues at the Joint Committee on Vaccination and Immunisation, the scientific committee, which advises the UK Department's of Health on immunisaiton, to ensure the best scientific decision can be made for the NHS.

So, are chickenpox parties a good idea? No. Chickenpox is at best an unpleasant disease, and at worst leads to life-threatening complications. We can't escape the disease, and in countries with a vaccine programme in place, vaccination is by far the safest option to defend the health of our children and those who are vulnerable in the community.

Andrew J. Pollard is Professor of Paediatric Infection and Immunity at the University of Oxford.

The views expressed in this article are the author's own.​​​​​​