World Health Organization - The composition for the southern hemisphere influenza season (2001) has been decided and communicated to vaccine manufacturers. It is recommended that the influenza vaccine will contain the following three components:

• An A/Moscow/10/99 (H3N2)-like virus (A/Panama/20007/99 is this kind of virus).
• An A/New Caledonia/20/99 (H1N1)-like virus.
• A B/Sichuan/379/99-like virus.

WHO strongly recommends the use of vaccine as an effective preventive measure against this potentially fatal disease. About 50 - 80% of vaccine recipients will be protected against the disease when there is a good match between the vaccine and strains of circulating influenza virus. However, in those cases where the vaccine does not fully protect against influenza, severity of illness and frequency of complications are reduced.

Most populations have been previously exposed to influenza A(H3N2), influenza A(H1N1) and B viruses and are known to have some degree of residual immunity. One dose of influenza vaccine should therefore be sufficient for all ages except young children. Previously unimmunized children should receive two doses of vaccine at an interval of at least four weeks.

The specific vaccine viruses used in each country should be approved by the national control authorities who are responsible for making recommendations on their use.

Reference: Weekly Epidemiological Record, 75: 330-333 (2000).