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NEW
ROCHELLE, NY — January 12, 2004
With a strong early start to the influenza season this year and
concerns about sufficient supply of vaccine, people are particularly
fearful of contracting influenza, even those who received the vaccine.
What is most troubling is the appearance of infections caused by
a strain of influenza that does not precisely match the strains
in this year's vaccine.
"This
year, the flu type-A strain included in the vaccine is related to,
but different from the strain circulating," says Gianna Zuccotti,
M.D., Deputy Editor of The Medical Letter on Drugs and Therapeutics."While
the vaccine may not provide full protection, the Centers for Disease
Control believes that it should still provide some cross-protection."
According
to The Medical Letter (Sept. 29, 2003), for healthy patients
between the ages of 5 and 49 who have not been able to be vaccinated
with the traditional inactive vaccine there is an alternative available:
FluMist, a new nasal spray form of the influenza vaccine. The
Medical Letter says that FluMist appears to be about as effective
as injected vaccine for this patient population, although it is
an expensive option. Because FluMist contains live virus, it should
not be used in health care workers and others who have contact with
people who have weak immune systems.
What
if you were unable to get the injected vaccination, or received
it but are concerned that you might be exposed to influenza before
the vaccine begins to work? The Medical Letter says that
treatment with oral antiviral drugs may be useful for people at
high risk for influenza-related complications, if an outbreak occurs
before or less than two weeks after vaccination, or if the circulating
strains prove to be different from the vaccine strains.
Three
oral drugs have been FDA approved for prevention of flu. According
to The Medical Letter, oral amantadine (Symmetrel) or rimantadine
(Flumadine), started before exposure and continued throughout exposure
(up to 6-8 weeks), can prevent illness due to type A flu in 70 to
90% of adults. Both drugs can be used in children who are at least
one year old, and are available generically. Amantadine can cause
insomnia, lightheadedness, nervousness, difficulty concentrating,
delirium, hallucinations and seizures. Rimantadine can also have
these effects but they are less frequent than with amantadine. Oseltamivir
(Tamiflu) and zanamivir (Relenza) are about 70 to 90% effective
for prevention and treatment of flu type A or B. Oseltamivir's adverse
effects include nausea, vomiting and headache. Zanamivir is not
FDA approved for prevention of flu. It's side effects include cough,
nasal and throat discomfort, headache and, in patients with asthma,
bronchospasm.
"These
antiviral drugs could interfere with the efficacy of the nasal FluMist
vaccine," said Dr. Zuccotti, "and should not be started
for at least two weeks after and should be stopped 48 hours before
taking the FluMist vaccine."
About
The Medical Letter
The Medical Letter Inc., a nonprofit organization founded in 1958,
offers health care professionals objective, independent analyses
of both prescription and over-the-counter drugs. In addition to
its newsletters, The Medical Letter on Drugs and Therapeutics
and Treatment Guidelines from The Medical Letter,
it also publishes handbooks and software on topics such as adverse
drug interactions and antimicrobial therapy. The Medical Letter,
Inc., is supported entirely by subscriber fees and is based in New
Rochelle, NY. For more information about The Medical Letter call
(800) 211-2769 or visit their Web site at www.medicalletter.org.
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