Influenza: Not a time for complacency

  • Infectious Disease News, October 2013
    Timothy Jones, MD

As influenza season approaches, it is important that the annual ringing of alarm bells inure neither medical providers nor our patients into complacency. As our surveillance systems improve, the profusion of public messaging about the threat of influenza has become nearly year-round: “Get your influenza vaccine now, before the annual epidemic strikes!” in the fall; “It’s not too late to get vaccinated, even though flu is here!” in the winter; “Avoid swine contact at fairs” in the summer; “Avian flu strikes China” this spring (no vaccine, but maybe later); and the current potentially confusing undercurrent of the “Bat Out of Hell? Egyptian Tomb Bat May Harbor MERS Virus.”

On top of this, intermittent debates about the efficacy of influenza vaccine in public forums may feed skepticism about a valuable preventive intervention, which can already be a hard sell. Although all (or at least most) of these messages are important, it is incumbent on the medical community to help sort them out for our patients and ensure that they act on those most critical for their health.

There is a lot that could be said, but a number of issues from the past year will be particularly useful in informing our messaging.

Vaccines available for this season

A CDC study estimates that during a 6-year period, influenza vaccination prevented 13.6 million cases, 5.8 million medical visits and nearly 113,000 influenza-related deaths.

Despite our efforts, influenza vaccine coverage rates remain disappointing. Preliminary estimates for 2012-2013 show that only 55% of children and 35% of adults were vaccinated; less than two-thirds of health care personnel and fewer than half of pregnant women receive it. It is also of concern that there are substantial racial disparities in influenza vaccination rates (38% among white adults vs. 29% in blacks).

Timothy F. Jones

Timothy F. Jones

Shipments of the 2013-2014 seasonal influenza began in August, and more than 135 million doses will be widely available this year. Everyone aged at least 6 months should get it.

A number of quadrivalent seasonal influenza vaccines (targeting two A and two B viruses) are available this year, including both live-attenuated and inactivated influenza vaccines. Work continues on development of a desperately needed universal vaccine.

A recent large study found no association between Guillain-Barré syndrome and influenza (or any other) vaccine.

The sensitivity (reported range of 10% to 80%) and positive predictive value of current rapid influenza tests can be horrid, and they should be used very thoughtfully.

Oseltamivir (Tamiflu, Genentech) and zanamivir (Relenza, GlaxoSmithKline) remain effective against common influenza viruses. High levels of resistance to adamantanes persist in currently circulating influenza A viruses, and they are not effective against influenza B.

In 2013, 16 cases of H3N2v swine flu were reported in three states, far fewer than 2012 numbers (309 cases).

Avian influenza A(H7N9)

This newly emergent virus has received substantial media attention and generated a vigorous response from the CDC. Thus far, all cases have had epidemiologic links to China. As of August, 135 cases had been reported, with 44 (33%) deaths. Cases peaked in March and April, and there is yet to be any evidence of sustained human-to-human transmission. Laboratory diagnosis is available through public health laboratories, and CDC websites have extensive recommendations on detection and control (www.cdc.gov/flu).

The government has taken steps to develop an H7N9 vaccine, although no decision has yet been made to produce it. In the event of a pandemic, vaccine is likely to be distributed through public health channels (as in the 2009 H1N1 pandemic), and it would behoove providers to contact their health departments to ensure that they are registered to receive it if that becomes necessary. Most health departments also have list serves that will send important updates to clinicians, who are encouraged to sign up for them.

Preparations for influenza are under way, but it is worth noting that the threat of Middle East respiratory syndrome (MERS) coronavirus remains a substantial concern to the CDC and international public health agencies and could strike concurrently. As of late August, 103 cases and 49 (48%) deaths had been reported, all with epidemiologic links to the Middle East (predominantly Saudi Arabia). There are concerns that the Hajj to Mecca in October, which attracts more than 3 million visitors per year, could facilitate dissemination of the virus. The CDC regularly posts recommendations for travelers and health care providers regarding MERS coronavirus on its website.

Predictions about the timing and severity of annual influenza epidemics are notoriously inaccurate, but if the media quote enough of us, some are bound to be correct. The one thing I do know is that if we all make a strong effort to educate and immunize our patients (and colleagues) appropriately, it will be far less severe than it otherwise could be.

References:

Baxter R. Clin Infect Dis. 2013;57:197-204.
CDC. Advisory Committee on Immunization Practices. MMWR. 2013;62:356.
CDC. Centers Guidance for Clinicians on the Use of Rapid Influenza Diagnostic Tests. 2013. www.cdc.gov/flu/professionals/diagnosis/clinician_guidance_ridt.htm#interpretation. Last updated Aug. 27, 2013. Accessed Sept. 19, 2013.
CDC. Health Care Personnel Flu Vaccination: Internet Panel Survey, United States, November 2012. www.cdc.gov/flu/fluvaxview/hcp-ips-nov2012.htm. Last updated July 17, 2013. Accessed Sept. 19, 2013.
CDC. Pregnant Women and Flu Shots: Internet Panel Survey, United States, November 2012. www.cdc.gov/flu/fluvaxview/pregnant-women-2012.htm. Last updated Dec. 3, 2012. Accessed Sept. 19, 2013.
Kang SM. Virus Res. 2011;162:31-38.
Kennedy ED. Influenza Vaccination Coverage: How Well Did We Do in 2012-2013. National Adult and Influenza Immunization Summit. www.cdc.gov/flu/fluvaxview/1213season.htm. Last updated May 2, 2013. Accessed Sept. 19, 2013.
Kostova D. PLoS One. 2013;8:e66312.
Kupferschmidt K. Bat out of Hell? Egyptian Tomb Bat May Harbor MERS Virus. American Academy for the Advancement of Science. news.sciencemag.org/health/2013/08/bat-out-hell-egyptian-tomb-bat-may-harbor-mers-virus. Science Now. Last updated Aug. 22, 2013. Accessed Sept. 19, 2013.
Li CK. Curr Opin Immunol. 2013;25:470-476.

For more information:

Timothy F. Jones, MD, is the State Epidemiologist for the Tennessee Department of Health, Nashville. He is also a member of the Infectious Disease News Editorial Board. He can be reached at Communicable and Environmental Disease Services and Emergency Preparedness, Tennessee Department of Health. 1st Floor, Cordell Hull Building, 425 Fifth Ave. North, Nashville, TN 37243; email: tim.f.jones@tn.gov.

Disclosure: Jones reports no relevant financial disclosures.