Management of Novel H1N1 "Swine Flu" in Children and Adults

A consensus statement from the Departments of Pediatrics and Emergency Medicine, Medical College of Georgia, Augusta, Oct 1, 2009

Novel H1N1 "Swine Flu" is a new sub-type of influenza A that appeared near the US/Mexico border region in April of 2009. Although initial reports from Mexico suggested a very high mortality rate, subsequent data indicate that this virus actually has relatively low virulence and is no more dangerous than seasonal influenza. Young people have been disproportionately infected by H1N1 so far. Roughly 30,000-40,000 Americans die from seasonal flu each year, 90-95% of whom are over age 65. Fewer than 100 US children died from seasonal flu in the 2008-2009 season, but hospitalization rates are especially high for children under 2 years of age who are infected with flu.

Swine flu has continued to circulate throughout the summer months in the United States, a highly unusual occurrence for a virus that normally appears in January or February and virtually always disappears by May. It is not yet clear why this virus has continued to circulate outside its normal "season," but the degree of spread around the world has been extensive enough to fit the definition of a pandemic, which was declared by the World Health Organization in June of 2009. In the last two influenza pandemics in 1957 and 1968, between 1 million and 2 million people died worldwide. In the 1918 flu pandemic, the largest Pandemic in world history, 50-100 million people died worldwide including 500,000 Americans.

Based on data from the CDC, a special White House Panel recently estimated that between 60,000 and 90,000 Americans may die from the Swine Flu before the 2009-2010 flu season is over. The CDC believes this is an overestimate. The reason for the high number is because 30-50% of Americans may become infected this season due to the fact that this is a new virus and the human population has no pre-existing immunity. In years with routine seasonal flu, attack rates generally are 5-10%. The higher morality figures are not due to higher virulence than with seasonal flu; they are simply a reflection of far more people getting infected. However, H1N1 has been most severe in adolescents and young adults, which so far have accounted for the majority of infections.

Flu activity in the CSRA clearly increased after schools reopened during the second week of August. Clinic and emergency department physicians have reported unusually high volumes of children presenting with fever PLUS either cough or sore throat, a symptom complex satisfying the CDC case definition of "influenza-like illness", or ILI. ILI is highly predictive for flu during periods of high flu activity. Georgia Department of Community Health (DCH) has documented a sharp increase in ILI throughout the state beginning in mid-August, and flu activity in Georgia is currently classified as "widespread."

During the first month of the Swine Flu outbreak in the Spring, there were reports of near panic in many US cities. The same was not true in Augusta. In general, the local media did an excellent job of providing accurate, non-sensationalized information to the public. As a result, we did not see the massive increases in clinic or emergency department volumes that were experienced around the rest of the country.

The Fall and Winter months are likely to be highly stressful as the public in the CSRA becomes aware of just how significant even a "mild" influenza pandemic can be. Tens of thousands of Americans dying from "Swine Flu" will likely lead to sensational stories in the national press, with anxiety levels ratcheting up in every community. In order to keep anxiety levels low in our own community, it is essential that the public be kept informed with consistent, accurate information. It will also be helpful if CSRA physicians are aware of national recommendations for the management of flu and try to adhere to them. Highly variable management of flu by area physicians will lead to confusion and angry patients. For the latest recommendations please go to the CDC flu website (www.cdc.gov/flu) and click on H1N1. A short list of important points for CSRA physicians and some current CDC and Georgia DCH recommendations follow, with short explanations. Be aware that these recommendations may change as the pandemic progresses, so please stay informed.

Management of H1N1 Influenza in Children and Adults

1. Specific testing for H1N1 is not necessary or available for most outpatients. CDC and Georgia Department of Community Health labs have the primers necessary to perform an RT-PCR assay to confirm novel H1N1, but individual hospitals and clinics generally do not. The Georgia Public Health Laboratory at DCH will not accept samples for H1N1 identification unless the patient is hospitalized.
2. Influenza rapid tests should not be used to guide therapy. The sensitivity of commercially available rapid flu tests for novel H1N1 is quite low, lower than for seasonal flu. Half or more of patients with H1N1 infections may test falsely negative with rapid flu tests even though they actually have the infection. If a patient has typical flu symptoms when flu is known to be circulating they should be assumed to have flu even if a rapid test is negative. For this reason physicians should use clinical symptoms to guide management, not rapid tests. For more about influenza rapid tests for H1N1 go to http://www.cdc.gov/h1n1flu/guidance/rapid_testing.htm
3. Novel H1N1 has been confirmed in the CSRA. There have been a number of cases confirmed at local hospitals during July and August, including at least 23 cases confirmed from Fort Gordon.
4. No currently available influenza rapid test can identify novel H1N1. Only the much more complex RT-PCR can do this. Physicians SHOULD NOT tell patients they have novel H1N1 on the basis of rapid test.
5. As of Sept 26, 99% of circulating influenza viruses nationwide were novel H1N1. This does not mean all flu can be attributed to novel H1N1, especially in a specific region. Seasonal sub-types of flu may continue to co-circulate and may account for a larger proportion of infections during the winter months.
6. In hospitalized patients with suspected flu, consider treatment with a combination of a neuraminidase inhibitor and an adamantane. Since the subtype will probably not be known for several days at a minimum, dual treatment is recommended by CDC when there is known co-circulation of H1N1 and seasonal influenza. The reason for this is that human A/H1N1 that has circulated for three decades is currently resistant to Tamiflu, while human A/H3N2 is resistant to the adamantanes.
7. The neuraminidase inhibitors oseltamivir (Tamiflu) and zanamivir (Relenza) are effective against novel H1N1. The older adamantane class of anti-influenza medications (Amantadine, Rimantadine) are not. The Federal Government has temporarily approved the use of Tamiflu in children under one year of age under an Emergency Use Authorization (EUA), which provides Tort protection to medical providers.
8. Treatment with antiviral therapy should be reserved for patients with high-risk medical conditions or hospitalized patients. Indiscriminate use of antiviral medications is likely to lead to increased rates of resistance to neuraminidase inhibitors. If this happens, we may have no antiviral treatment available for subsequent patients with novel H1N1 infection. For this reason, both the CDC and the World Health Organization strongly advise against widespread use of prophylaxis for health care professionals. They also recommend the use of antiviral medications only for hospitalized patients or for patients with ILI who have high risk medical conditions. These high risk conditions include: pregnant females; adults over age 65; patients in nursing homes or chronic care facilities; children under age two (children 2-5 were removed from the high risk list on Sept 22 by CDC); any patient with a history of severe pulmonary disease (Cystic fibrosis, severe asthma, COPD, etc), severe cardiac disease (except hypertension), hematologic disease (Sickle Cell), immunodeficiency (cancer patient on chemotherapy, HIV/AIDS), renal disease, diabetes mellitus, or neurologic disease associated with decreased ability to expand the lungs. For the full recommendations, go to www.cdc.gov/h1n1flu/recommendations.htm
9. Most patients with influenza-like illness should stay home and receive supportive care alone. Most patients with flu will be symptomatic up to 4-6 days before showing improvement. Patients with high risk medical conditions and ILI should seek medical care if antiviral medications are available, but children over age 5 and otherwise healthy adults under 65 generally do not require medical evaluation unless their symptoms are prolonged (e.g. fever greater than 5 days) or unusually severe (unable to stand, difficulty breathing/shortness of breath, severely diminished urine output, etc.) Supportive care includes plenty of fluids, bedrest, and antipyretics/pain medications (not aspirin). For children less than five years of age, cough and cold medications are not recommended.
10. The best strategy for prevention is vaccination. Seasonal flu vaccine will be available as usual, and vaccine against H1N1 will be available by October. Both vaccines should be given for maximal protection.
11. Return to work or school is appropriate when the patient has been afebrile for 24 hrs. Due to the lower level of viral shedding than with seasonal flu, prior advice to exclude for 7 days is no longer valid.

Also See:

Algorithm for Management of Flu in Children

The AAP's website for physicians on pandemic influenza.