Lower respiratory viral infections in immunocompetent children.

Viral lower respiratory disease causes a heavy burden on our society. Better understanding of the epidemiology of these viruses combined with new rapid diagnostic techniques will provide more rapid and more reliable diagnosis of these agents in the future. Two agents not commonly thought of as causes of LRI in children (rhinoviruses, coronaviruses) should now be added to an already long list. Effective drugs exist for prophylaxis against influenza virus type A and therapy for influenza virus type A, type B, and RSV. While no new antiviral drugs are near clinical use at this time, new antiviral agents are constantly being tested and developed. High-titer, specific antiviral IVIG appears promising for both therapy and prophylaxis. Over the next decade, improved influenza virus vaccines and safe and effective vaccines against HPIV and RSV are expected. Adenoviral vaccines for use in immunocompromised patients are possible, but a generally available vaccine for all children is less likely. Although the basic clinical epidemiology of these viruses has been well investigated over the last 30 years, new molecular techniques are greatly expanding our understanding of these agents. Antigenic and genetic variation is being found in many viruses previously thought homogeneous. The exact role and biologic significance of this variation is just beginning to be explored, but already there is evidence of differences in pathogenicity and immunogenicity in many of these substrains. All of this information will have an impact on future vaccine and antiviral drug development.