Ethnic minority children and children with severe chronic diseases died at a disproportionate rate during the H1N1 pandemic of 2009 and 2010, a U.K. government study has found, and the influenza pandemic proved deadlier to England’s children in general than did leukemia in any given year.

In the U.K. children with severe chronic diseases and ethnic minority children died from the H1N1 influenza virus (shown here) at disproportionate rates, according to a study published in the Lancet.

In their analysis of all 70 laboratory-confirmed H1N1 deaths in England for people younger than 18 years, published online Oct. 27 in the Lancet, Dr. Liam J. Donaldson of the U.K. National Patient Safety Agency and Dr. Nabihah Sachedina of the U.K. Department of Health showed overall pediatric mortality from pandemic influenza to have been 6 per million population. This rate is three times as high as England’s normal estimated pediatric death rate up to age 14 years for seasonal influenza, and slightly higher than the Netherlands death rate of 5 per million (in children under age 14) during the pandemic period (Lancet 2010 Oct. 27 [doi:10.1016/S0140-6736(10)61195-6]).

More prone to fatal pandemic H1N1 infection in England, the investigators found, were children born to Bangladeshi and Pakistani families – 47 and 36 per million, respectively, compared with 4 per million for white children. The authors said the finding “might be attributable to clustering of pandemic influenza A(H1N1) cases in areas of England with high ethnic minority populations,” although areas with lower ethnic minority populations were also affected, they noted. The authors allowed that more preexisting disorders might be present among ethnic minority children, but said there were few data to support the claim; among the 70 cases studied, preexisting health status did not differ among ethnic groups, they said.

Of the 70 fatal pediatric H1N1 cases recorded between June 26, 2009, and March 22, 2010, children with severe preexisting disease accounted for 45, or 64%, the investigators found; 15, or 21%, were healthy, and the rest had mild or moderate existing disease. Deaths occurred evenly between boys and girls (31 and 39, respectively), with the median age at death 7 years. Children under age 1 year also saw a higher rate than children as a whole (14 per 1 million population).

“Chronic neurological, gastrointestinal, or respiratory disease were all present in more than half of all deaths,” the authors wrote. Of the 35 children with neurological disorders who died, 19 had spastic quadriplegic cerebral palsy. Half of the school-age children who died had attended schools for children with special needs; nearly a quarter had been born prematurely. A prior diagnosis of asthma was present in 5 deaths, complex congenital cardiac disease was reported in 8, severe gastroesophageal reflux was reported in 11, and regular gastrostomy or nasogastric feeding took place in 41.

Some 27% of the deaths occurred before the child could be admitted to a hospital, the researchers said, and children in this group were likelier to have been healthy or to have only mild preexisting disorders than were those who died after admission.

In more than three-quarters of the deaths, primarily respiratory symptoms were reported at presentation; in two cases, mainly gastrointestinal symptoms were reported. Among hospital deaths, nearly a quarter of the children presented in cardiorespiratory arrest; only one presented with nonspecific symptoms, the investigators said.

Importantly, only two of the children who died had been vaccinated, and they had received vaccine too late – within 2 days before becoming sick – for it to be effective, they said.

The investigators concluded that children with the identified risk factors for death from influenza should be prioritized for vaccination.

The study was funded by the U.K. Department of Health. Dr. Donaldson was the chief medical officer for England from 1998 to May 2010. In this role he advised the government on the management of the pandemic. Dr. Sachedina supported him in this task from 2009 to 2010. They declared that they had no additional conflicts of interest.

In a comment accompanying the article, Dr. Robert A. Fowler and Dr. Philippe Jouvet of Sunnybrook Hospital, University of Toronto, said the fact that previously healthy children accounted for more than one-fifth of the deaths was a serious concern as well (Lancet 2010 Oct. 27 [doi:10.1016/S0140-6736(10)61385-2]).

“Although this finding is not more important than the identification of underlying medical risk factors, it represents a persistent message of the H1N1 pandemic – that children and young adults who were not expected to become severely ill because of influenza did so, and in greater numbers than with seasonal influenza,” they wrote.

Dr. Fowler and Dr. Jouvet declared they had no conflicts of interest.

Pediatric H1N1 Fatalities High Among Ethnic Minorities, Chronically Ill