Exacerbations in children with asthma are often
associated with viral infections(1). Although the contribution by
influenza virus to this exacerbation has not been fully quantified
several guidelines recommend immunization of asthmatic subjects
against influenza. A question is asked in various forums whether
there should be a policy to vaccinate children with influenza
vaccine in India. The primary goal of influenza vaccination policy
has been the reduction of excess deaths associated with influenza
epidemics(2). While influenza may cause asthma exacerbations,
there has been concern that vacciantion may precipitate an asthma
attack in some people.
One previously done review had concluded that
this vaccine does not benefit patients of asthma an chronic
obstructive pulmonary disease(3). A recent Cochrane review has
addressed this problem systematically to assess the effects of
influenza vaccination in children and adults with asthma(4). The
source of the articles included in the review was the Cochrane
Airways Groups trials register which is a data base maintained by
the Cochrane airways group with its editorial base at London. The
reference lists of articles were also checked.
Randomized trials of influenza vaccination in
children (over two years of age) and adults with asthma were
included. People with chronic obstructive pulmonary disease were
excluded. Inclusion criteria and assessment of trial quality were
applied by two reviewers independently. Data extraction was done
by two reviewers independently. Study authors were contacted for
Nine trials were analyzed. Four of these trials
were of high quality. The studies covered a wide diversity of
people, settings and types of influenza vaccination, so data from
the different trials were not pooled. In one trial, no protective
effect of influenza vaccination against asthma exacerbation was
demonstrated, but the inci-dence of influenza was low during the
study period. A higher number of asthma exacerba-tions following
killed influenza vaccination was found in one trial (risk
difference 3.1%, 95% confidence interval 0.3% to 5.9%). When
people with upper respiratory tract infections were excluded, this
difference was no longer significant. A small trial using
recombinant vaccine found no significant difference in asthma
exacerbations between the vaccinated and placebo groups.
The reviewers did not find enough evidence to
assess the benefits and risks of influenza vaccination for people
with asthma. Whatever evidence is available is not of sufficient
quality to assess the usefulness of this vaccine in asthmatic
subjects. It has been recommended that large randomized controlled
trials be conducted with sufficient power to detect the difference
in the exacerbation rate amongst these individuals. Moreover, in
countries like India where enough information is not available
about the prevailing influenza virus strains this vaccine which
has a potential to be ineffective after a few years even in the
countries where it is produced cannot be routinely recommended.
Advanced Pediatric Center,
Post Graduate Institute
of Medical Education and Research,
Chandigarh 160012, India.
1. McIntosh K, Ellis EF, Hoffman LS, Lyban TG,
Ellis JJ, Fulginiti VA. The association of viral and bacterial
respiratory infections with exacerbation of wheezing in young
asthmatics. J Pediatr 1973; 82: 578-590.
2. Barker WH, Mulloly JP. Pneumonia and
influenza deaths during epidemics. Arch Int med 1982; 142: 85-89.
3. Rothbath PH, Kemper BM, Sprenger MJ. Sense
and nonsense of influenza vaccination in asthma and chronic
obstructive pulmonary disease. Am J Respir Crit Care Med 1995;
4. Cates CJ, Jefferson TO, Bara AL. Vaccines for preventing
influenza in people with asthma. The Cochrane Library, 1999, Issue
4. Update Software. Oxford, UK.