Impact of influenza A/H1N1v infection in CF compared to other risk groups

Background : During the influenza A/H1N1 (A/H1N1) pandemic, CF patients (pts) were considered at risk for severe complications, as for seasonal flu. Data on the real impact of A/H1N1 in CF are scare.
Aims : To evaluate the impact of A/H1N1 infection in ourCF clinic (150pts) during the Belgian pandemic Oct-Dec 2009, compared to other risk groups, and to the impact of seasonal flu in previous years.
Methods : In all CF patients presenting during the pandemic with fever or pulmonary exacerbation, we collected nasal secretions for PCR and culture and/or blood for serology, to detect respiratory viruses including A/H1N1. All pts are annually, correctly vaccinated against seasonal influenza.
Results : A/H1N1 was detected in 15 CF pts (9 aged 0_15 yrs, 4 adolescents and 2 above 18 yrs), in 15 (non CF) children with neurodevelopment desease (NDD), and in 79 healthy children. 12/15 CF pts received oseltamivir, wich was well tolerated, 10/15 received antibiotics of which 4/10 intravenously. Only one 9 yrs old CF girl had permanent respiratory decline with chronic hypoxemia. In our previous seasonal influenza survey 17/21 CF pts were hospitalised and 8 had prolonged oxygen need. In NDD pts A/H1N1 led in 3/15 to lethal respiratory complications (SARI) and in 1/15 to lobectomy. 24/79 healthy children had bacterial pneumonia without any permanent sequelae.
Conclusion : Chronic respiratory disease and NDD are considered as risk factors for complicated A/H1N1 infection. Our data suggest that A/H1N1 may be less dangerous in CF than seasonal influenza A despite seasonal vaccination. CF pts seem less at risk compared to NDD patients. Vaccination of vulnerable groups remains crucial.