WHO recommendations for management of H1N1 Infections
Ashwin Udyavar
antiviral treatment for novel influenza A (H1N1) and other influenza.
The purpose of the new recommendations, which were posted online
August 20, is to provide a basis for advice to clinicians regarding
the use of the currently available antivirals for patients presenting
with illness caused by influenza virus infection, as well as
considerations regarding potential use of these antiviral medications
for chemoprophylaxis.
On the basis of a review of data collected with previously circulating
strains, and treatment of human H5N1 influenza virus infections, the
new guidelines expand on recommendations published in May 2009, titled
ʺClinical management of human infection with new influenza A (H1N1)
virus: Initial guidance." These new guidelines do not change
recommendations in the WHO rapid advice guidelines on pharmacological
management of humans infected with highly pathogenic avian influenza A
(H5N1) virus.
"In April 2009, the [WHO] received reports of sustained person to
person infections with [H1N1] virus in Mexico and the United States,"
write Edgar Bautista, from Médico Neumólogo Intensivista, Jefe de
UCI-INER in Mexico, and colleagues. "Subsequent international spread
led WHO to declare on 11 June 2009 that the first influenza pandemic
in 41 years had occurred. This 2009 pandemic H1N1 influenza virus has
now spread worldwide, with confirmed cases of pandemic H1N1 virus
infection reported in more than 100 countries in all 6 WHO regions[,
which] has led to the need to add to the existing guidance on the use
of antivirals."
The new recommendations highlight oseltamivir and zanamivir, which are
neuraminidase inhibitors, and amantadine and rimantadine, which are M2
inhibitors. Suggestions are also provided regarding the use of some
other potential pharmacological treatments, such as ribavirin,
interferons, immunoglobulins, and corticosteroids.
Management of patients with pandemic influenza (H1N1) 2009 virus
infection is the primary focus of the statement, although it also
includes guidance regarding the use of the antivirals for treatment of
other seasonal influenza virus strains, as well as for infections
resulting from novel influenza A virus strains.
The guidelines urge country and local public health authorities to
issue local recommendations for clinicians periodically, based on
epidemiological and antiviral susceptibility data on the locally
circulating influenza strains. As the prevalence and severity of the
current pandemic evolves, WHO anticipates that additional data will be
forthcoming that may require revision of the current recommendations.
WHO therefore plans to review the guidance no later than September
2009 to determine whether modifications to the recommendations are
needed.
Recommendations for Antiviral Treatment of H1N1:
For patients with confirmed or strongly suspected infection with
influenza pandemic (H1N1) 2009, when antiviral medications for
influenza are available, specific recommendations regarding use of
antivirals for treatment of pandemic (H1N1) 2009 influenza virus
infection are as follows:
•Oseltamivir should be prescribed, and treatment started as soon as
possible, for patients with severe or progressive clinical illness
(strong recommendation, low-quality evidence). Depending on clinical
response, higher doses of up to 150 mg twice daily and longer duration
of treatment may be indicated. This recommendation is intended for all
patient groups, including pregnant women, neonates, and children
younger than 5 years of age.
•Zanamivir is indicated for patients with severe or progressive
clinical illness when oseltamivir is not available or not possible to
use, or when the virus is resistant to oseltamivir but known or likely
to be susceptible to zanamivir (strong recommendation, very low
quality evidence).
•Antiviral treatment is not required in patients not in at-risk groups
who have uncomplicated illness caused by confirmed or strongly
suspected influenza virus infection (weak recommendation, low-quality
evidence). Patients considered to be at risk are infants and children
younger than 5 years of age; adults older than 65 years of age;
nursing home residents; pregnant women; patients with chronic comorbid
disease including cardiovascular, respiratory, or liver disease and
diabetes; and immunosuppressed patients because of malignancy, HIV
infection, or other diseases.
•Oseltamivir or zanamivir treatment should be started as soon as
possible after the onset of illness in patients in at-risk groups who
have uncomplicated illness caused by influenza virus infection (strong
recommendation, very low quality evidence).
Recommendations for Chemoprophylaxis of H1N1
Specific recommendations regarding the use of antivirals for
chemoprophylaxis of pandemic (H1N1) 2009 influenza virus infection are
as follows:
•When risk for human-to-human transmission of influenza is high or
low, and the probability of complications of infection is high, either
because of the influenza strain or because of the baseline risk of the
exposed group, use of oseltamivir or zanamivir may be considered as
postexposure chemoprophylaxis for the affected community or group, for
individuals in at-risk groups, or for healthcare workers (weak
recommendation, moderate-quality evidence).
•Individuals in at-risk groups or healthcare personnel need not be
offered antiviral chemoprophylaxis if the likelihood of complications
of infection is low. This recommendation should be applied independent
of risk for human-to-human transmission (weak recommendation,
low-quality evidence).
For treatment of mild to moderate uncomplicated clinical presentation
of infection with multiple cocirculating influenza A subtypes or
viruses with different antiviral susceptibilities, patients in at-risk
groups should be treated with zanamivir or oseltamivir plus M2
inhibitor (noting that amantadine should not be used in pregnant
women). Otherwise-healthy patients with this presentation need not be
treated.
When the clinical presentation of infection with multiple
cocirculating influenza A subtypes or viruses with different antiviral
susceptibilities is severe or progressive, all patients should be
treated with oseltamivir plus M2 inhibitor, or zanamivir.
For treatment of mild to moderate uncomplicated clinical presentation
of infection with sporadic zoonotic influenza A viruses including
H5N1, the at-risk population should be treated with oseltamivir or
zanamivir, and the otherwise-healthy population with oseltamivir. All
patients, regardless of risk status, with severe or progressive
presentation of infection with sporadic zoonotic influenza A viruses
including H5N1 should be treated with oseltamivir plus an M2
inhibitor.
hope this is useful
regards
Dr.Ashwin
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