Scientists said on Thursday that vaccinating children against chickenpox (varicella) could increase the risk that adults would develop shingles, a painful blistering rash that is potentially dangerous in the elderly.
The team, at Britain's Public Health Laboratory Service (PHLS), said that although vaccination would save thousands of lives over time, thousands of elderly people could also die from the complications of shingles, known as herpes zoster.
Writing in the journal Vaccine, they called for a re-evaluation of the policy of mass chickenpox vaccination that has been introduced already in the United States and is imminent in many other countries. In 1995, the chickenpox vaccine was approved for use in children over 1 year of age in the US and is now required for school entry.
After a bout of naturally-occuring chickenpox, the varicella zoster virus remains dormant in the body and may reactivate decades later to cause shingles, a painful rash that typically strikes chickenpox veterans after the age of 60.
Marc Brisson and his team say their research shows that adults living with children have more exposure to the virus that causes chickenpox and enjoy high levels of protection against shingles. Being close to children means that adults are exposed to the virus, which acts like a booster vaccine against shingles, they believe. But if all children were vaccinated, adults who have had chickenpox would no longer be protected against developing shingles.
The researchers worked out a mathematical model that predicts that eliminating chickenpox in a country the size of the United States would prevent 186 million cases of the disease and 5,000 deaths over 50 years. However they said it could also result in 21 million more cases of shingles and 5,000 deaths.
The PHLS said in a statement
it was working out what the impact might be of
introducing a chickenpox vaccine in Britain. "As more evidence becomes available, it will be shared with the Joint Committee on Vaccination and Immunisation, which advises the Department of Health on the immunisation schedule.
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