H1N1 flu Info

Information is evolving rapidly. For the latest information visit CDC general influenza page and CDC H1N1 page.

The purpose of this page is to not provide definitive resource but rather to have central reference for how our clinic is interpreting guidelines.

Initially emerging in April of 2009 and came to Oregon in May the H1N1 strain of influenza appeared. Being a novel strain that includes reassortment from pig, bird and human strain, the majority of the population do not have antibodies to this or similar strains. It was initially called “swine flu” due to being in the same class as “swine flu” that emerged in 1970’s. Pigs can become infected with this virus but only when alive. No reason to avoid bacon! The most accurate name for this vaccine is H1N1 2009 Pandemic strain. This differentiates it from “swine flu” of the 1970’s and differentiates it from other H1N1 influenza strains that are already circulating.

Symptoms

So far symptoms of H1N1 influenza are similar to “regular” seasonal influenza. Primary difference is the fact it is circulating outside the usual winter season. It appears to be very easy to transmit but overall causes shorter duration of illness. There were initial fears based on prior flu pandemics that when a new strain emerges it causes more severe disease, resulting in widespread morbidity and mortality. So far this does not appear to be occurring in our country or in the southern hemisphere (that is now finishing their winter flu season). H1N1 was the most common influenza seen in the southern hemisphere and likely to be the most common type of influenza this coming winter.

Diagnosis of H1N1 influenza should be considered when the following symptoms are present (numbers in parenthesis is percent of confirmed cases that had each symptom):

  • Fever (93%)
  • Cough (83%)
  • Shortness of breath (54%)
  • Nasal congestion (36%)
  • Muscle aches (36%)
  • Headache (31%)
  • Sore throat (31%)

Risk factors for severe disease

Just as with seasonal influenza the following groups are at higher risk for complications from infection and should be prioritized for vaccination and more consideration given to antiviral medication:

  • Patients under 5 years old, with highest risk being kids under age 2
  • Pregnant woman
  • Patients with chronic pulmonary disease (such as asthma), obesity, heart disease, diabetes, Down syndrome, cerebral palsy, and other conditions that depress immune system or inhibit ability to handle secretions.

Unlike seasonal influenza the elderly appear to be a decreased risk compared to other age groups.

Testing

Initially testing was important to document incidence in the community. It is now known to be widespread so testing for public health reasons is no longer necessary. In past flu seasons we haven’t placed a firm emphasis on testing unless patient was placed in the hospital. Guidelines are moving towards similar recommendations again. Testing should only be considered in patients at high risk of complications (see above) and those patients admitted to the hospital. This is the same group of patients where antiviral medications would be considered (see below) and should be primary consideration when testing.

Prevention

Primary prevention is same as for any other respiratory viral infection. Recommendations include:

  • Wash hands frequently
  • Cough into your sleeve
  • Avoid crowds in enclosed places
  • Patients with symptoms should stay home from work or school until fever has resolved for at least a day

Antiviral treatments

Treatment with ‘’‘oseltamivir (Tamiflu)’‘’ should be considered for:

  1. Anyone requiring hospitalization for H1N1 infection.
  2. Children younger than 2 years of age.
  3. Pregnant women
  4. Adults 65 years and older
  5. Anyone with severe chronic illness placing them at high risk for complication
  6. Anyone on daily aspirin therapy.
  7. Any suspected influenza patient who is presenting with signs or symptoms of lower respiratory tract involvement (low oxygen, breathing fast, working harder to breathe)

Capsules can be opened and compounded into suspension by pharmacy if needed.

Side effects are common and include nausea and vomiting. Dose should be reduced in patients with renal disease.

Treatment should begin ideally within the first 48 hours of illness and should not be delayed for laboratory confirmation of diagnosis.

Prophylaxis is not indicated except in those persons with likely exposure to H1N1 and who are at high risk for influenza related complications. Cases of resistance are still rare but most cases have occurred in patients that received prophylaxis or were severely immunocompromised. Early treatment is better than prophylaxis. In other words, if high risk contact of known case becomes symptomatic treatment should be started ASAP (called in).

We are experiencing a busy winter season and we are planning to work hard to meet the health care needs of our patients. We will do our best to smile and keep our sense of humor! Be patient with us.