Special Section: H1N1 Flu
Putting H1N1 into Context
In its very unpredictablility, this year's pandemic fits a pattern. That's according to Arnold Monto, professor of epidemiology at the School of Public Health, one of the world’s leading authorities on pandemic influenza. He explains more below. As a member of the President’s Advisory Council on Science and Technology 2009-H1N1 Working Group, he helped advise the White House on preparations for H1N1 this fall. Monto also serves on the WHO Emergency Committee.
It has been 40 years since the last influenza pandemic. In 1968, the A (H3N2) viruses emerged, causing what turned out to be a pandemic of moderate severity—approximately twice as bad as a seasonal outbreak. Severe outcomes, including death, were mainly in the traditional risk groups—the elderly, those of any age with underlying conditions, and the very young.
Since so much time had passed since the last pandemic, many experts thought we were overdue for a new pandemic, and the likely candidate was judged to be avian influenza type A (H5N1). In 1997, this virus did something that was unprecedented—it jumped directly from poultry to people. Previously, it was thought that the virus needed to go through pigs before it could transmit to humans.
This form of avian influenza has become a persistent infection in poultry in countries as far apart as Indonesia and Egypt. Occasional transmission to humans has occurred, with the production of severe disease, often resulting in death. Secondary transmission to others, typically family members, has occurred, but sustained transmission has not taken place. However, because these cases have continued, and adaptation to the human host is always possible, the A (H5N1) threat has been taken seriously, and treated as the potential cause of the next pandemic. Global planning for such an event continued at an accelerated pace. Paradoxically, by early 2009, there was concern that pandemic fatigue was starting—despite continued A (H5N1) cases in a number of countries.
With influenza, the unpredictable often becomes the reality. There were press reports in April 2009 that Mexico was experiencing an unusual increase in severe respiratory illnesses. The virus, a type A (H1N1) distinctly different from the seasonal virus, was identified when it spread to San Diego, California. Virologists quickly characterized it as being of swine origin with its eight RNA segments coming from various swine, avian, and even human sources.
In their earlier planning for a possible avian influenza pandemic, public health officials had wondered whether air travel would increase the rapidity of spread. An unequivocal answer emerged when outbreaks of type A (H1N1) began within weeks in many disparate areas of the United States and Canada. On April 25, the World Health Organization Emergency Committee met by teleconference, and for the first time under the new International Health Regulations, advised the Director General to declare this “a public health emergency of international concern.”
On April 27, the committee recommended raising the pandemic alert level to phase 4, indicating that there was sustained human-to-human transmission. Two days later, the WHO declared phase 5—meaning the disease had spread in several countries in one WHO region. It took an additional six weeks to reach phase 6, the full declaration of a pandemic. Why did this take so long? For such a declaration to be made, public health officials had to document and formally report community transmission in another WHO region. This happened on June 11.
A complicating issue was that many countries had prepared for only a severe pandemic, and that under the terms of those preparations, as soon as a pandemic was declared, these countries would be compelled to adopt certain measures, including the closure of their borders, which was contrary to WHO recommendations. These countries needed time to change their regulations, and the world needed to be educated that pandemics can have different degrees of severity.
As we move forward, the global public health community is working to improve its ability to define severity; this is critical, since historically pandemics have occurred at irregular intervals, and avian H5N1 is still causing deaths on a regular basis. Thus, we must remain vigilant in dealing with this unpredictable virus, and not only manage the current H1N1 pandemic, but also look to any future pandemics. —By Arnold Monto
H1N1 Surveillance in Michigan
If she could convey just one message about H1N1—the novel strain of flu that emerged in Mexico last spring and has since become a global threat—it would be that “the picture of influenza is really made up of a number of moving parts, and it takes some analysis to make sense of it,” says School of Public Health alumna Eden Wells, M.D., M.P.H. ’03, a medical consultant and epidemiologist with the Bureau of Epidemiology, Michigan Department of Community Health (MDCH), and an adjunct associate professor at SPH.
As the facilitator of the Michigan Pandemic Influenza Coordinating Committee, Wells is at the forefront of Michigan’s efforts to monitor the spread of novel H1N1 this fall. What everyone wants to know, she says, is how many cases of H1N1 there are in the state on a given day. But while that question may seem simple, its answer is not. A majority of novel H1N1 cases are subclinical or mild and don’t get reported, Wells explains. “What does get reported are patients who go to their doctor or hospital and get tested.” Not all patients require laboratory testing, so the full impact of influenza on a community involves much more than simply counting the number of clinical tests performed.
In order to obtain the most accurate picture of H1N1 in Michigan this flu season, MDCH is enhancing its multi-faceted influenza surveillance strategy, the principal components of which are:
- Passive Surveillance: Because novel H1N1 is a “notifiable” disease, laboratories, physicians, and school health officials who encounter cases of H1N1 are asked to report those cases to their local health department. “Rapid notification is key,” says Wells, adding, “most of the time what we know in public health is because somebody has picked up the phone or e-mailed us.” Most passive reporting occurs from hospitals and laboratories within the state. When widespread illness occurs, however, aggregate reporting of the numbers of influenza cases—rather than of specific individual cases—is utilized.
- Sentinel Physicians: Michigan has approximately 100 sentinel physicians—what Wells calls “canaries in the coal mine”—in 42 counties, as well as a network of sentinel laboratories. These health care providers include family care, pediatric, and emergency care clinicians who agree to send swabs from patients with flulike symptoms directly to the state health department. Collectively, this information allows health officials to see how, when, and where H1N1 is moving through their state.
- Communication of Surveillance Information: The State of Michigan issues weekly MiFluFocus and FluBytes reports on H1N1 at www.michigan.gov/flu.
- Active Surveillance: MDCH and local health departments are able to access records from physicians’ offices, clinics, and hospitals to acquire information about how H1N1 is affecting patients.
- Syndromic Surveillance: New surveillance systems enable public health officials to be alert to potentially significant patterns of community illness. For instance, when patients with flulike symptoms register in an emergency department, Wells says, their symptoms (not patient information) trigger an electronic message that’s sent securely to MDCH. Another system uses consumer barcoding data from participating retail pharmacies. MDCH monitors over-the-counter sales of anti-fever and cold medications, thermometers, electrolyte solutions, chest rubs, nasal sprays, and other products used to treat flulike symptoms.
Watch “Introduction to Public Health, Outbreak Investigations and Influenza,” a 75-minute presentation by Eden Wells, sponsored by the Michigan Center for Public Health Preparedness as part of Public Health in the Spotlight: Communicating Health Risks (archived webcast PHSRA0809).
As students began trickling back onto the University of Michigan campus in August and UM health officials launched a series of efforts aimed at keeping them as healthy as possible in the midst of an influenza pandemic, second-year MPH student Alyse Grossman found herself wanting to help.
Grossman had spent the summer in Lansing, helping the Michigan Department of Community Health analyze vaccination data from its Michigan Care Improvement Registry. Her focus was seasonal flu vaccination data from the 2008–2009 season. Thanks to her labors, state public health officials learned that approximately 80 percent of the flu vaccines that were administered last year in Michigan came from private providers, and that of those Michigan children who needed to get two doses of flu vaccine, only a small percentage—under 50 percent—did. Both findings have obvious implications for this year’s efforts to administer vaccinations against both H1N1 and seasonal influenza.
At UM, health officials were planning to conduct mass vaccination clinics for both H1N1 and seasonal influenza. Grossman volunteered her expertise and helped put the officials in touch with SPH students who could help staff the big events. She also answered questions from students at a University Health Service open house and distributed pamphlets urging UM students to get vaccinated. It’s all part of real-world practice for Grossman, who hopes to stay in Michigan after graduation next year and get a job working on communicable diseases in a local health department.