H1N1 (Swine Flu)

The world was rocked in late March 2009 when a new strain of Influenza A virus was first detected in Mexico, followed by cases in the United States. It is unknown whether humans have natural immunity. This novel strain consisted of genetic elements from four different viruses: North American swine influenza, avian influenza, human influenza, and swine influenza typically found in Asia and Europe. Infected pigs act as a mixing pot in which re-assortment occurs between flu viruses of several species, in this case pig and human.

The first recognized case was in a 5-year-old boy in the home village of La Gloria, near Perote in the Mexican state of Veracruz. The boy started feeling unwell in late March, suffering fever, headache, and sore throat. He recovered. It remains a mystery as to how the boy contracted the virus. Local people have blamed the outbreak of sickness on nearby pig farms. All the ingredients were present for a pandemic recipe: lots of people in close proximity to pigs and birds; poverty; poor sanitation; and lack of access to medical care. However, to date, this novel virus has yet to be isolated from pigs.

As of May 13, 2009, there are 5,728 worldwide, laboratory-confirmed cases in 33 countries across five continents, with 61 deaths. The median age of confirmed cases is 16, with an age range of 3 months to 81 years. Mexico has 2,059 confirmed cases and accounts for 56 deaths, mostly in those with co-morbidities. The United States has 3,352 confirmed cases in 45 states, with three deaths (two in Texas and one in Washington).

When we talk about lessons learned, it’s not as if we don’t have any prior experience to draw upon. On March 5, 2003, the world was introduced to SARS. It lasted six months, and infected 8,000 people in 25 countries with 775 deaths. The infection disrupted travel, trade, and the workplace. The cost to the Asia Pacific region was $40 billion. Canadian hospitals were overwhelmed and surge capacity exceeded, (e.g., isolation rooms, ventilators, and supplies). We dodged the bullet in the United States. The virus was eliminated from the human population once infection-control practices were refined in the severely affected areas. Most recently, the world was bracing for the next pandemic, with concerns that the widespread Avian Influenza (H5N1) virus in 2005 with a case fatality ratio close to 60 percent would spread globally. To date, this virus has not acquired the ability to easily and sustainably transmit from human to human.

So what did we learn? Even though the public anxiety was elevated, media coverage may have facilitated in containing, investigating, and increasing financial aid in limiting the outbreak in Mexico. As would be expected with all the public awareness, people were scared. Emotions ran high and confusion set in — not just in the public sector but in the medical community as well. Anyone with fever, cough, and/or sore throat flooded community clinics, physician offices, urgent care, and emergency rooms. The sudden influx of patients with respiratory symptoms quickly tested individual healthcare facilities’ pandemic plans, surge capacity, and supplies such as gloves, masks, and gowns. Questions arose as how to test for swine flu. There was some question as to whether the rapid Influenza A tests (in short supply) reliably tested for swine influenza. Clinicians were frustrated. The county public health laboratory was overwhelmed with a backlog of samples to confirm the presence of seasonal versus untypeable strains (probable swine influenza) of Influenza A. It had to prioritize those samples submitted to hospitalized patients with ILI (influenza-like illness) because the laboratory could only test ~ 20 samples a day. Untypeable influenza A specimens were sent to the Centers for Disease Control & Prevention for verification. Many clinicians did not know how to get samples to the appropriate labs for testing.

The next question was, who got treated? The window of opportunity to administer antivirals such as oseltamivir (Tamiflu) was within 48 hours of symptom onset in people with chronic conditions, those under 5, those 65 and older, and pregnant women, but treatment guidelines were not promptly promulgated. The experience in the United States so far has been that H1N1 looked like a mild seasonal influenza with little mortality. It was recommended that patients without underlying morbidities, such as heart disease, diabetes, renal disease, immunocompromised states, and patients who were otherwise well with mild symptoms, not seek medical attention and remain at home for seven days or until symptoms resolve (whichever was longer), and that antiviral therapy not be prescribed. Patients who develop severe disease, particularly those with co-morbidities, were advised to seek medical attention and to be evaluated for possible hospital admission, viral cultures, antiviral treatment, and supportive care. Despite the fact that the majority of influenza isolates were due to seasonal influenza H1N1 (resistant to oseltamivir), many clinicians elected to treat only for swine influenza.

We also learned that few pharmacies, hospitals, and clinics kept large supplies of antivirals on hand. In the last week of April alone, more than one-quarter of a million prescriptions for oseltamivir were filled at U.S. pharmacies. This could have been critical considering that antiviral treatment and prophylaxis treatment doses were in short supply. About 25 percent of the federal stockpiles were released nationally and became available locally in the following days.

The initial defense strategies to slow the spread and transmission of any pandemic flu are stringent infection-control procedures, respiratory hygiene, and cough etiquette (cover your cough and clean your hands). This is backed up by considerable scientific research. “The single most effective step against the spread of flu is hygienic measures around younger children” (Cochrane Collaboration 10-17, 2007). The message got out in print, media, and news coverage. The importance of stressing “source control” cannot be overemphasized.

Some hospitals ran short of other supplies but were able to tap stock at other affiliated hospitals. Even with all the pandemic planning, it was clear that supplies such as protective masks, gloves, isolation gowns, and hand sanitizers were in short supply in the community. In a real pandemic you will also see disruption of supply chains for food, medicines, and electricity.

The question arose as to who should stay at home. There were staffing issues. In the end, it was recommended that anyone with fever, cough, and/or sore throat stay home for seven days. Those who had little cough and no known contacts with suspected cases could wear a mask at work if they worked in areas at low risk of complications. The concept of social distancing was put into effect: maintaining a distance of 6 feet at work and not shaking hands. Business was not done as usual.

More than 700 schools were closed nationwide, affecting ~ 468,000 children. Initially, schools were closed one week. Then the recommendation was changed to two weeks. When influenza becomes widespread in a well-defined community, isolation of potentially infected patients makes sense (British Medical Journal, Nov. 27, 2007). In this case, the downside of closures may have outweighed the benefits. Parents were not able to take off work or had to go without pay or use vacation time. Closures also impacted healthcare staffing. The irony was that school closures were meant to cut down on contact, but students had plenty of contact anyway, as toddlers and children played in parks while adolescents gathered in shopping malls.

Vaccine production for this fall’s seasonal flu has been in full swing. We learned that we do not have the critical manufacturing capacity to make both seasonal flu vaccine and H1N1. A decision will have to be made soon as to whether to stop current production and gear up for H1N1. The 1918 Spanish Influenza started out as a mild seasonal flu. It returned in the fall as the deadly pandemic that resulted in an estimated 50 million deaths worldwide, with 675,000 in the United States. As H1N1 hits the Southern Hemisphere, we need to watch what it does. It is clear that we need to develop a faster process to grow viruses for vaccine production in this country. This will be critical for us to meet the challenges as newly recognized pathogens continue to emerge.

The greatest risk from pandemics might not turn out to be from the swine flu virus but from the “collateral damage,” particularly from an already-fragile economy. With border controls and disruption of world trade, global recession could worsen, damaging prospects of economic recovery. A 2008 World Bank report estimates a severe pandemic could reduce the world’s GDP by 4.8 percent. We depend on international trade. H1N1 negatively impacted education, transportation, commerce, and tourism, causing school closures and flight cancellations.

The importance as well as the effectiveness of stringent infection-control procedures was never more apparent than in Mexico. Closing schools, limiting public gatherings, restricting travel, screening at airports, use of personal protective equipment, practicing hand hygiene and covering cough, attention to cleaning the environment, and use of antivirals had a major impact in slowing the spread of swine flu. The response globally was rather quick and appropriate, with a few exceptions. There was little reason for the Chinese government to have quarantined Mexican tourists in their hotel rooms or for the Egyptian government to have ordered the slaughter of all of the country’s hogs. It should be noted, however, that this is a traditional response of Muslim countries to swine-borne illness. Pigs were not spreading the disease to humans, and clinical influenza cannot be transmitted through consumption of pork; hence the concern about use of the word “swine” when referring to the virus.

We also learned that up-to-date information was critical. The San Diego County Medical Society spearheaded this effort with daily updates initially, with input from the GERM Commission experts. Additional expertise was sought from Dr. Bruce Haynes, Dr. Michele Ginsberg, and the Public Health Department — in particular Dr. Wooten, who led the charge countywide. The community response was good, the public health department did an excellent job, and those pandemic influenza plans were dusted off and put into effect. Fortunately, in response to Senate Bill 739 (2006), all healthcare facilities were required to have a pandemic plan in place. This is a time to fine-tune and update their plans. Areas that require more focus include infection-control strategies in the triage and assessment areas of emergency departments, clinics, and urgent care centers, management of the “worried well,” ability to rapidly test specimens, promoting “source control,” and increasing seasonal influenza vaccination compliance.

Let’s not forget the lessons learned. The virus is still present. We need to remain on alert. It will be back.