DENMARK: Contrary to the fears of some parents, a 10-year study by Danish researchers found no evidence that combination vaccines, such as the measles, mumps and rubella (MMR)shot, weakened children's immune system.
The study, published yesterday in the Journal of the American Medical Association, tracked 805,206 children born in Denmark.
The study found no increased rate of pneumonia, diarrhoea, blood infections, and viral or bacterial infections of the nervous system among vaccinated children. The study "should be reassuring to parents", said Dr Margaret Rennels, a paediatrics professor at the University of Maryland who was not involved in the study.
The Danish researchers, led by Anders Hviid, an epidemiologist at Denmark's Statens Serum Institut, followed all children born in Denmark between 1990 and 2001 who received a number of common vaccines against infectious diseases, including MMR, haemophilus influenza type b, or Hib, and oral polio virus. Using the unique personal ID number assigned when each Danish baby is born, Prof Hviid's team was able to track information on all vaccinations and hospitalisations for illnesses related to infectious diseases.
The team found only one potential adverse effect: children who received the influenza vaccine were 5 per cent more likely to be hospitalised for upper respiratory tract infections than unvaccinated children. But Prof Hviid said the increased rate was not statistically significant.
The controversy over vaccines first emerged in 1998, when Andrew Wakefield, a researcher at London's Royal Free Hospital, published a study linking the MMR vaccine with autism and bowel disease in children.
Although studies have since discounted this association, it prompted many parents in Britain to shun the vaccine, causing a five-fold increase in mumps and a doubling of measles cases between 2002 and 2003.