Influenza Vaccine Composition Recommendation
for the 1989-90 Season
During the 1988-89 influenza season, influenza type B has
predominated
in the United States but has cocirculated with type A(H1N1) and
A(H3N2). Elsewhere in the Northern Hemisphere, type A influenza has
generally predominated, with both influenza A(H1N1) and A(H3N2)
cocirculating.
Antigenic analysis of type A(H1N1) viruses from outbreaks
indicates
that most strains are closely related to the U.S. vaccine strain,
A/Taiwan/1/86. The antibody induced by this vaccine component
reacts
well with the recently circulating type A(H1N1) viruses.
As in last season, type A(H3N2) viruses continue to be
heterogeneous.
Some isolates resemble the current vaccine strain A/Sichuan/2/87,
but
most are better inhibited by antiserum to the A/Shanghai/11/87
reference virus (Table 1). In addition, patients vaccinated with
A/Sichuan/2/87 vaccine consistently had lower antibody responses to
the
A/Shanghai/11/87 strain (Table 2) than to the vaccine strain.
Most influenza B strains isolated this season, particularly in the
United States, are similar to the current vaccine component,
B/Victoria/2/87. However, a new variant was identified in Asia;
B/Yamagata/16/88 is an example of the variant (Table 3). This
strain
was first seen in the People's Republic of China in August 1987 and
circulated in Japan, Hong Kong, Singapore, Taiwan, and Thailand
from
February 1988 to January 1989. The antibody induced by the current
B/Victoria/2/87 vaccine component is poorly reactive with the
B/Yamagata/16/88 strain (Table 4).
Based on these and other data, the World Health Organization (WHO)
has
recommended that the trivalent influenza vaccine for use in the
1989-90
season contain the following components: type A(H3N2),
A/Shanghai/11/87-like antigen, and type B/Yamagata/16/88-like
antigen
and retain the type A(H1N1) component of the current vaccine. This
decision has been ratified by the Food and Drug Administration's
Vaccine Advisory Panel.
Reported by: P Gross, MD, Hackensack Medical Center, Hackensack,
New
Jersey. P Palmer, K Edwards, MD, Vanderbilt Univ, Nashville,
Tennessee.
F Ruben, MD, Univ of Pittsburgh, Pennsylvania. Influenza Research
Center, Baylor College of Medicine, Houston, Texas. G Schild, PhD,
National Institute of Biological Standards and Control, London,
United
Kingdom. National Influenza Centers, Microbiology and Immunology
Support Svcs, World Health Organization, Geneva. Div of Virology,
Office of Biologics, Food and Drug Administration. Participating
state
and territorial epidemiologists and state laboratory directors. WHO
Collaborating Center for Influenza, Influenza Br and Epidemiology
Office, Div of Viral Diseases, Center for Infectious Diseases, CDC.
Editorial Note
Editorial Note: Influenza type A viruses are classified into
subtypes
on the basis of two antigens: hemagglutinin (H) and neuraminidase
(N).
Three subtypes of hemagglutinin (H1, H2, H3) and two subtypes of
neuraminidase (N1, N2) are recognized among influenza A viruses
that
have caused widespread human disease. Immunity to these antigens,
especially the hemagglutinin, reduces the likelihood of infection
and
the severity of disease if infection occurs. However, over time
there
may be enough antigenic variation (antigenic drift) within the same
subtype that infection or vaccination with one strain may not
induce
immunity to distantly related strains of the same subtype.
Antigenic
variation occurs with influenza B viruses, although no subtypes are
known to exist. For these reasons, major epidemics of respiratory
disease caused by new variants of influenza continue to occur. The
antigenic characteristics of current strains provide the basis for
selecting virus strains included in each year's vaccine.
The manufacturing, quality control, and distribution process
involved
in producing about 30 million doses of influenza vaccine in the
United
States require many months to complete. Therefore, the decisions on
which strains to include in the vaccine formulation for the 1989-90
influenza season must be completed by late March to early April of
1989. Specific recommendations by the Immunization Practices
Advisory
Committee will be available later this spring.
Disclaimer
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