Babies should be vaccinated against chickenpox at the same time as they have the MMR vaccine, medical experts have urged.

They believe that it is the only way to prevent a hundred children a year from suffering severe complications caused by the disease – several of whom die.

Chickenpox is almost universal, with about 300,000 cases every year in the UK. Almost everybody catches it, usually before the age of 15. It is a mild illness in children, but in rare cases can cause severe complications.

To assess how common the worst complications are, a team led by Claire Cameron, of Health Protection Scot-land, asked consultant paediatricians in Britain and Ireland to record all severe cases between November 2002 and November 2003.

There were 112 cases, all requiring hospital treatment, with conditions such as pneumonia, blood poisoning, encephalitis, ataxia (loss of control of limbs), toxic shock and necrotising fasciitis (the flesh-eating bug).

Six deaths were recorded, the team reports in Archives of Disease in Childhood, the journal of the Royal College of Paediatrics and Child Health. This figure is in line with previous data that suggests that between four and eight children die from chickenpox every year.

The authors say that most of the cases could have been prevented by routine vaccination, but none could have been anticipated and prevented by selective vaccination.

Evidence elsewhere has shown that even partial vaccine coverage provides substantial “herd immunity”, which would extend protection to children under one year old who had not yet been vaccinated.

Routine vaccination against the disease is the “only realistic way of preventing deaths and severe complications”, the doctors say.

The Joint Committee on Vaccination and Immunisation (JCVI) is already considering adding the chickenpox vaccine to the childhood schedule. In addition to the rare severe cases in children, chickenpox causes serious complications and some deaths among adults – about 20 a year, recent statistics suggest.

But chickenpox vaccination would be controversial. As well as the controversy over MMR, there are medical issues to consider. The varicella-zoster virus responsible for chickenpox lingers in the body and can emerge again much later in life, when the immune system begins to falter, in the form of shingles.

The prevalence of chickenpox in the community is believed to act as a brake on shingles, by keeping people’s immune systems alert to the virus.

It is possible that vaccinating children, and lowering the overall level of infection greatly, could make adults who have had chickenpox more susceptible to shingles.

Countries that use the vaccine against chickenpox routinely, such as the US, have not been doing so for long enough to show whether these concerns are justified. Studies in the US are contradictory, with one showing a big rise in shingles and another no change.

One way round this problem would be to vaccinate the elderly against shingles, the team says.

In an editorial in the journal, three specialists from Bristol say that in the US, where vaccination was introduced in 1995, hospital admissions and death from chickenpox have fallen by two thirds, but that protection from a single injection is incomplete.

The “simple, obvious and easy” way would be to add the varicella vaccine to MMR, to create MMRV, the Bristol specialists say. Two doses would provide good protection.

Such is the misplaced public concern about MMR, however, that adding another vaccine could reduce the uptake. The risk would be of reducing protection against measles, mumps and rubella (German measles), while not protecting adequately against chickenpox and shifting the burden of the disease to adults.A possible short-term strategy would be to vaccinate teenagers who had not had chickenpox, with the aim of preventing severe disease in adults, while getting the public used to the idea of a vaccine.

The Department of Health said: “JCVI has commissioned an expert subgroup to look at all the scientific and medical evidence on varicella [chickenpox] vaccines, including this recently published paper, and it will provide advice in due course.”

The Herpes Viruses Association has doubts about a vaccine programme. “Chickenpox in adults is often much worse than in children. If the vaccine wears off we are just storing up problems for the future,” said Nigel Scott of the association.

“If we had to choose between the two, we would advocate vaccinating the elderly, as shingles is far more likely to cause serious health problems in many more people than is chickenpox in the young.”

History of a sharp weapon

— Vaccination began in 1796 when Edward Jenner developed an effective vaccine against smallpox

— Vaccines for cholera, anthrax, rabies, tetanus, diphtheria, typhoid and plague had followed by the end of the 19th century

— Today, by the time children reach the age of 5, they should have had a total of 12 injections, protecting them against ten diseases: diphtheria, tetanus, pertussis (whooping cough), polio, HIB meningitis, meningitis C, pneumococcal infection, measles, mumps and rubella

— The discovery of polio vaccine in the 1950s launched one of the biggest crash vaccination programmes in history. The disease is now on the verge of being eradicated

— The greatest success of recent years was the introduction of meningitis C vaccine in 1999, which cut cases of the brain disease from hundreds a year to a handful