# 7163
While no cases have been reported outside of China, on Thursday afternoon in a detailed COCA call, the CDC informed clinicians of freshly minted guidelines on the H7N9 virus.
Yesterday we looked at their PPE and infection control recommendations (see CDC Interim H7N9 Infection Control Guidelines), while Scott McPherson wrote about clinician surveillance here in the United States (see CDC begins actively looking for H7N9 in the United States).
Last night, Lisa Schnirring of CIDRAP News covered the new antiviral guidance. First her report, then I’ll return with more:
CDC offers antiviral guidance for possible H7N9 cases
Lisa Schnirring
Staff Writer
Apr 18, 2013 (CIDRAP News) – The Centers for Disease Control and Prevention (CDC) today released initial antiviral guidance to help health workers prevent and manage H9N7 avian flu cases that may one day be detected in the United States.
In a clinicians conference call today, Alicia Fry, MD, MPH, said though there have been very few cases of suspected human-to-human spread of the virus in China, the CDC is monitoring the situation closely there and is looking for cases in the United States. She added that the agency is especially monitoring for people who get sick after traveling to China or who were exposed to someone who was infected with the virus.
So far no cases have been detected in the United States or any other country outside of China.
Apr 18 CDC H7N9 interim antiviral guidance
Apr 11 CDC H7N9 interim infection control guidance
As the CDC’s representatives emphasized in yesterday’s call, there is still much we don’t know about this virus, including its pathogenicity in humans. Many of the cases we are aware of have experienced severe symptoms, but how many mild cases their might be, we simply don’t know.
So, the base their antiviral guidance upon:
These interim recommendations are based upon current information and the following considerations:
- Current lack of a vaccine for H7N9 virus
- Severe H7N9 disease with substantial mortality to date
- Limited current human-to-human H7N9 virus transmission but potential for increased transmission in the future
Clinicians should consider the possibility of avian influenza A(H7N9) virus infection in persons presenting with acute febrile respiratory illness and an appropriate recent travel or exposure history (see Interim Guidance on Case Definitions to be Used for Novel Influenza A (H7N9) Case Investigations in the United States).
While this guidance provides specific recommendations for hospitalized and outpatient treatment, their basic guidance reads:
Influenza Antiviral Treatment Recommendations
- Because of the potential severity of illness associated with H7N9 virus infection, it is recommended that all confirmed cases, probable cases, and H7N9 cases under investigation (see Interim Guidance on Case Definitions to be Used for Novel Influenza A (H7N9) Case Investigations in the United States) receive antiviral treatment with a neuraminidase inhibitor as early as possible. Treatment should be initiated even if it is more than 48 hours after onset of illness.
- Laboratory testing and initiation of antiviral treatment should occur simultaneously; treatment should not be delayed for laboratory confirmation of influenza or H7N9 infection. (For information regarding case investigation, specimen collection and laboratory testing, please see the CDC Health Alert Network issued on April 5, 2013.
- Please see Antiviral Drugs: Dosage (ACIP) for additional guidance on the use of influenza antiviral agents, including dosage recommendations for treatment by age group. Oseltamivir is recommended for treatment of persons of any age; zanamivir is recommended for children aged 7 and older. Clinicians may refer to the manufacturer’s package inserts for additional information regarding dosing, contraindications, and potential adverse events.
Under hospitalized patients, the CDC concedes:
The optimal duration and dose of therapy are uncertain in severe or complicated influenza. Pending further data, longer courses of treatment (e.g., 10 days of treatment) should be considered for severely ill hospitalized H7N9 patients.
This interim guidance may be adjusted in the future as more is learned about how this virus operates, and the effectiveness of treatment.
Regarding the medicine itself, it has not been without controversy. Its value has been questioned by Cochrane meta-studies, medical journals, conspiracy theorists, pundits, and the press.
Roche Pharmaceuticals has been widely criticized for their past refusals to release all of the testing data on their best selling antiviral drug, which has led to critical editorials in the BMJ, and excoriation in the British press.
Despite a paucity of `gold standard’ Randomized control trials (RCTs) proving its effectiveness, there are studies that show that Tamiflu can significantly reduce morbidity and mortality associated with influenza.
In 2010 an observational study appearig in JAMA (see Study: Antivirals Saved Lives Of Pregnant Women) strongly suggested that Tamiflu was life saving for some patients with pandemic flu.
And again in 2010, in BMJ: Efficacy of Oseltamivir In Mild H1N1, we saw a study which suggested that the administration of oseltamivir may have significantly reduced the incidence of pneumonia among otherwise healthy pandemic H1N1 patients.
Quite recently, in December of 2012, in Study: The Benefits Of Antiviral Therapy During the 2009 Pandemic we looked at a meta-analysis of 90 observational studies that appeared in the Journal of Infectious Diseases that spanned nearly 35,000 patients, 85% of whom has laboratory confirmed H1N1.
Their main finding was antiviral therapy - principally oseltamivir - initiated within 48 hours of onset, reduced the likelihood of severe outcomes, namely admission to a critical care unit or death, by 49 to 65%.
And lastly, for those who question the value of Tamiflu in an avian flu pandemic, in Study: Antiviral Therapy For H5N1, we saw the largest study to date on outcomes of H5N1 patients who either received, or did not receive, antiviral treatment.
The research appears in the IDSA’s Journal of Infectious Diseases. The bottom line is essentially out of 308 cases studied, the overall survival rate was a dismal 43.5%.
But . . . of those who received at least one dose of Tamiflu . . . 60% survived . . . as opposed to only 24% who received no antivirals.
The caveat being that studies listed above dealt with either seasonal flu, pandemic H1N1, or the H5N1 avian flu virus.
How effective oseltamivir will be against H7N9 remains an open question.
One other point of concern is safety, particularly after reports of adverse effects (AEs) - including transient psychiatric symptoms in adolescents - made headlines a few years ago.
Again the news is reassuring.
In 2010 a review in the journal Eurosurveillance: Adverse Effects of Oseltamivir in Children, looked at the antiviral treatment of a number of students at a primary school in Sheffield, UK during the 2009 pandemic.
While none of the side effects reported were life-threatening, the nausea, vomiting, abdominal pain and other symptoms were bothersome enough that a minority of those who started the Tamiflu (< 10% ) stopped taking the drug.
More recently, in Study: Adverse Events Associated With Oseltamivir Outpatient Treatment, researchers writing in the journal Pharmacoepidemiology and Drug Safety, found that `no evidence was identified for an increased risk of neuropsychiatric or other AEs following oseltamivir treatment.’
The safety record of Tamiflu has been reassuring enough that last December the FDA approved its use in infants as young as two-weeks (see FDA expands Tamiflu’s use to treat children younger than 1 year).
Despite the critics, the preponderance of evidence continues to show that antivirals – including Tamiflu – can have a substantial positive therapeutic effect on influenza, particularly in high risk patients.
