Should the UK introduce a chickenpox vaccination?

At present, only healthcare workers and others likely to be at risk of contracting or passing on the infection, are routinely immunised in the UK. But vaccination programmes for children have been introduced in several other countries, including the USA, Canada, Australia, and Finland.

Adam Finn, Professor of Paediatrics at Bristol University and authors base their conclusions on active monitoring by paediatricians in the UK and Ireland of children up to the age of 16 admitted to hospital with severe complications resulting from chickenpox infection.

During the monitoring period, which ran for 13 months between 2002 and 2003, 188 cases were reported to the British Paediatric Surveillance Unit.

Of these, 112 children met the criteria, giving a case rate of 0.82 per 100,000. Their average age was three years.

The complications included septic shock, pneumonia, and encephalitis, as well as uncoordinated movement (ataxia), toxic shock syndrome, and “flesh eating” bacterial infection (necrotising fasciitis).

Almost half the children (46 per cent) had additional bacterial infections.

Six children died. One child died in the womb. Although four of the five other children, who were aged between two and 14 years, already had a pre-existing medical condition, these were not groups currently targeted for immunisation.

After discharge, four out of 10 children had ongoing problems as a result of their infection, including, most commonly, ataxia or skin scarring.

Their average length of hospital stay was seven days, but ranged from one to 68.

Most of these children were healthy before they contracted the virus, say the authors. Universal immunisation could have prevented their complications, as they were mostly old enough to have received the vaccine.

An accompanying editorial in the journal by Professor Finn and colleagues at the Bristol Royal Hospital for Children, comments: “Chickenpox has traditionally been viewed as an irritating but inevitable infection to be endured during childhood, a rite of passage during the preschool years.”

“This benign view persists despite evidence that certain groups, including neonates, adults, pregnant women, and the immunocompromised have higher risks of severe disease,” it continues.

The authors point out that new cases of chickenpox have been rising among pre-school children, and for every 1000 cases, between two and five children will have to be admitted to hospital.

The simplest strategy would be to switch from the triple MMR vaccine to one that also included immunity against chickenpox (varicella), using the recently licensed MMRV jab, say the authors. But unfounded fears about MMR are likely make this difficult to implement at present. But varicella vaccine could be offered to all teenagers who have not yet been infected.

“This could prevent cases of severe disease in adults and pregnant women and raise public awareness of the potential and desirability of primary prevention,” they conclude.

Source: University of Bristol