For over five years, doctors in India have been recommending chicken pox vaccination for children, even though it does not figure in the list of mandatory vaccinations, and no comparative study has ever been conducted.
Now they may have to do a rethink, after new studies in the US have raised doubts about its effectiveness. According to the study, published last week in The Journal of the American Medical Association, found the effectiveness of the vaccine is found to fade substantially a year after it is administered.
In children below 15 months, the vaccine appears to have less immunity. Experts are now questioning whether the vaccine for long a topic of debate in the US should be used at all, as immunisation just pushes the disease into adulthood when it could take a more severe form.
Adults whose childhood immunity has worn off could be in trouble later age as it increases their vulnerability to the disease, say experts. ''The findings do raise some pertinent questions. It is a matter of concern.'' says Dr Anupal Sibal, senior child specialist, Indraprastha Apollo Hospitals.
The study, carried out over several years by researchers at Yale Medical School, further found that in children above 15 months, protection was 99 per cent in the first year, and only 73 per cent in those below 15 months. However, those who got chicken pox after receiving the shots had only mild symptoms.
What's the solution for this then? Sibal suggests administering a second dose, "Even now, children beyond 15 years are recommended two doses." The catch: it's very expensive.