Mucosal immunization in perspective.

Pandemic and seasonal influenza viruses are a constant public health threat with substantial morbidity and mortality worldwide. Prophylaxis is hard to realize, but immunization provides an efficient tool to control the disease. Despite most infections occurring at or through mucosal surfaces, vaccines are predominantly administered parenterally. Recently it has been suggested that vaccines applied via mucosal surfaces may be a viable novel approach. A number of clinical studies have proven live attenuated influenza vaccine given intranasally to have equivalent or superior immunogenicity and efficacy at the upper and lower respiratory tract compared with systemic intramuscular vaccination. Intranasal application provides easy administration facilitating mass immunization campaigns which requires no strictly sterile injection and is painless to recipients.