We conducted a prospective, nested study using nucleotide sequencing to examine influenza positive respiratory samples in families for genetic homology in the hemagglutinin and neuraminidase genes. Influenza A H3N2 viruses from 3 families had identical, family specific, HA1 nucleotide sequences. Sequences among these families were genetically heterogeneous. A 4th family was distinguished by sequencing of the influenza neuraminidase gene.
From the *Centre for Child Health, Barts and the London, Queen Mary's School of Medicine and Dentistry, Queen Mary, University of London, UK; †Respiratory Virus Unit, Enteric, Respiratory and Neurological Virus Laboratory, Centre for Infections, Health Protection Agency, Colindale, UK; and ‡Virology Clinical Group, Barts and the London NHS Trust, London, UK.
Accepted for publication March 22, 2007.
Celia Aitkens's current address is Regional Virus Laboratory, Glasgow, Scotland.
Robert Booy's current address is The National Centre for Immunisation Research and Surveillance, The Children's Hospital at Westmead, Sydney, Australia.
Address for correspondence: Dr. Stephen Teo, Centre for Child Health, Barts and the London School of Medicine and Dentistry, Queen Mary College, University of London, 4 Newark Street, London E1 2AX, United Kingdom. E-mail: firstname.lastname@example.org.