Recommendations for Influenza Vaccine Composition
Southern hemisphere: May-October 2000
This recommendation relates to the composition of vaccines for the forthcoming winter in the southern hemisphere (May-October 2000). A recommendation will be made in February 2000, which relates to vaccines that will be used for the winter in the northern hemisphere (November 2000 to April 2001). Epidemiological considerations will influence which recommendation (September 1999 or February 2000) is more appropriate for countries in equatorial regions.
Consequently, it is recommended that vaccines to be used in the 2000 season (southern hemisphere winter) contain the following:
- an A/Moscow/10/99 (H3N2)-like virus;
- an A/New Caledonia/20/99 (H1N1)-like virus;
- a B/Beijing/184/93-like virus*
- a B/Shangdong/7/97-like virus.
* The most widely used vaccine virus is B/Yamanashi/166/98.
Addendum to the recommended composition of influenza virus vaccines for use in the southern hemisphere in 2000
On 1 October 1999, WHO made a recommendation on the composition of the influenza vaccine for use in 2000 in the southern hemisphere.
This recommendation remains valid. However, attempts by several laboratories to produce an A/Moscow/10/99-like vaccine strain with suitable antigenic properties and with a yield appropriate for vaccine production have to date been unsuccessful. At present therefore, it is not possible for manufacturers to include the recommended H3N2 component in vaccines to be available at the beginning of the southern hemisphere winter.
In these circumstances and since a majority of recent isolates are antigenically closely related to A/Sydney/5/97, it is acceptable that vaccines to be used in the 2000 season in southern hemisphere countries contain a high-yield A/Sydney/5/97-like virus as the A(H3N2) component.