Should more countries vaccinate children against chickenpox?

Vaccines sometimes generate unfounded health alerts, but the opportunity to vaccinate against chickenpox has been the subject of a real medical debate.

It’s a routine childbirth in some countries – including the US, Canada, Australia, Japan and around half of Europe – but holdouts include the UK, Denmark, France, Portugal and several Scandinavian countries. There are concerns that while the introduction of childhood vaccination will benefit those who receive it, it could be detrimental to others, such as older people at risk of shingles.

Fortunately, growing evidence suggests that such damage is not materializing. What’s more, an analysis released today finds that, overall, the vaccine does more good than harm. So, is it time for varicella vaccine-resistant countries to get their act together?

Chickenpox is caused by a highly infectious virus called varicella zoster. In the absence of vaccination, most people become infected in childhood and usually have mild illness, with the main symptoms being an itchy, blistered rash.

In fact, the younger a person is when they catch it, the milder their experience tends to be. Some families even deliberately expose their children to other infected people to “finish the disease”.

But the virus can sometimes cause serious symptoms – for example, if it triggers bacterial infections – and can even be deadly, especially in people with weakened immune systems.

When the first chickenpox vaccine was developed three decades ago, one of the concerns was that while it would benefit the children who received it, some parents might not have their children vaccinated. A routine vaccination schedule would mean population-level immunity would be relatively high, so those who missed out might not encounter the virus until they were teenagers or older, increasing the risk of serious complications. compared to childhood infection.

Another fear was the impact on the elderly. After infection with chickenpox, the DNA of the virus remains in nerve cells and can reactivate later in life, leading to the painful and debilitating symptoms of shingles. Chickenpox infections in children are thought to expose adults to small doses of the virus, boosting their immunity and making them less likely to develop shingles.

Despite concerns, the United States began routinely offering the vaccine to children in 1995, with other countries later following suit. Those who resisted can now see the results, suggesting the introduction of the vaccine was the right decision.

Several studies over the past few years have shown that the United States and other countries have not seen an increase in shingles cases. A UK study has found that if adults are exposed to a child with chicken pox in their household, their reduction in risk of shingles is less than previously assumed, with a drop of around 27% over 10-20 years .

Now, the data from these studies has been fed into a standard set of equations that predict the impact of vaccines on infection and disease rates. This was used to model the effects over 50 years if the vaccine was routinely offered to children in Denmark.

The researchers – which included scientists from Merck, a maker of one of the vaccines, and Aarhus University Hospital in Denmark – found that while there would be an increase of around 1% in cases of shingles during the first years after the introduction of vaccination, after 50 years the total number of cases would be 9% lower than expected if Denmark continued not to vaccinate.

They also found that the number of people of any age dying or needing hospital treatment for chickenpox would be reduced by more than 90%, countering the idea that there would be an increase in more severe cases of people unvaccinated catching the virus when they were older. .

Vaccination programs would also prevent some of the less obvious harms of this virus, including children missing school and parents having to miss work, says Manjiri Pawaskar at Merck in Rahway, New Jersey. “It places a significant burden on caregivers,” she says.

Several countries, including the UK and Denmark, are now considering adding the varicella vaccine to routine shots offered to children. Currently, many such countries allow people to pay for the vaccine privately, but that means uptake is low. Britain’s vaccine advisory group, the Joint Committee on Vaccination and Immunization, will consider any new data, a spokesperson for the UK Health Security Agency said.

For adults who have experienced chickenpox as a mild illness, it may be tempting to dismiss the need for vaccination against this disease. But one thing the covid-19 pandemic has shown is that even if a disease affects only a small percentage of the population severely, it can cause appreciable harm nationwide and is worth taking countermeasures. -measures.

Maybe it’s time for more countries to stop giving the varicella virus a pass.