A new study suggests that children vaccinated against flu are three times as likely to be hospitalized than those who are not.
According to as yet unpublished research reported at the 105th International Conference of the American Thoracic Society in San Diego on May 19th, the inactivated flu vaccine (trivalent inactivated flu vaccineTIV) does not appear to be effective for preventing influenza-related hospitalizations in children, espeically in those who suffer from asthma.
What's more, the researchers say that those children who receive the vaccine are actually more likely to be hospitalized than those who hadn't had a flu jab.
In the US the CDC's Advisory Committee on Immunization Practices (ACIP) and the American Academy of Pediatrics (AAP) recommend annual flu vaccinations for all children between six months and 18 years of age. In the UK the guidelines are less stringent with only at risk groups such as the chronically ill, atopic individuals, and the elderly routinely advised to have the shots.
According to Avni Joshi M.D. of the Mayo Clinic the safety of the TIV flu vaccine for children with asthma has been demonstrated by previous studies but its actual effectiveness has not. Joshi and collegaues at the Mayo Clinic therefore devised a study to obtain this information.
The team conducted a cohort study of 263 children aged between 6 months and 18 years who had had laboratory confirmed influenza between 1996 and 2006. The researchers determined which of the children had been given the flu vaccine, whether they suffered from asthma or not, and if they had been hospitalized due to complications of the influenza. Using medical records the investigators determined who had and had not received the flu vaccine, their asthma status, and who did and did not require hospitalization.
Perhaps surprisingly, what they found was that children who had received the flu vaccine were three times as likely to have been hospitalized, compared to children who had not received the vaccine. In children who suffered from asthma, there was a significantly higher risk of hospitalization in subjects who received the TIV, as compared to those who did not. The severity of a child's asthma and other factors such as levels of insurance cover, and hence quality and timeliness of care, did not reprotedly affect this associated.
While this study certainly provides food for thought, and many have been (understandably) quick to jump to the conclusion that vaccinating children against flu is actually dangerous, the picture is likely to be more complex. It is true however that the study suggests the vaccine appears to be ineffective and questions the logic of recommending it be given to all children.
However, medical study results are never clear cut due to the intracacies of the study design. It may be that children given the flu vaccine who subsequently ended up in hospital were those who were already in poorer health with more risk factors for complications of the flu.
Dr. Joshi told ScienceDaily: "While these findings do raise questions about the efficacy of the vaccine, they do not in fact implicate it as a cause of hospitalizations," adding that "More studies are needed to assess not only the immunogenicity, but also the efficacy of different influenza vaccines in asthmatic subjects."/p>