Facts and Fiction about H1N1 Influenza (Swine Flu)

In case you are totally clueless about H1N1, here's the CDC Fact Page.

I thought it would be a good idea to provide some information about the H1N1 flu, just because it's in the news, and unfortunately people are not always getting the right information. I'll do my best to debunk some of the myths and also to spread the knowledge. Most of this comes from a combination of my own background and what I've been told by immunologists and physicians at work, as well as some interviews I've heard on Science Friday, and also a lot from the CDC H1N1 page. I'll provide specific references in the form of links where I can.

Fiction: Hand sanitizer will keep you from getting the flu.

Fact: Influenza virus is not killed by alcohol-based sanitizers (according to Dr. J. Owen Hendley). The only surefire way to remove flu virus from your hands is to wash with soap and water, while rubbing hands together, for at least 20 seconds. Hand sanitizer will kill most bacteria and some other viruses, but not H1N1. Regular hand washing is the best defense.

Fiction: Flu vaccine causes you to get the flu.

Fact: The flu vaccine cannot give you the flu, as it consists of pieces of a dead virus that only serves as "training" for your immune system so that your cells will recognize the strains against which the vaccine was developed, so that your body can more efficiently fight off the virus. You may experience soreness at the injection site (I do, anyway), and if you are allergic to eggs (albumin) you should not get the flu vaccine.

Fiction: I don't need to get the vaccine, I haven't gotten the flu in years.

Fact: In general, the flu shot is a good idea for people who take care of small children and the elderly, as well as individuals in both of those populations. However, as a novel virus, H1N1 is a cause for greater concern because most people don't have an immunity of any kind against it. This seems to be manifested best in the observation that people under 50 have presented more cases than those over 50. According to the CDC (via Science Friday), as of May 11: "the more recent illnesses and the reported death suggest that a pattern of more severe illness associated with this virus may be emerging in the U.S. Most people will not have immunity to this new virus and, as it continues to spread, more cases, more hospitalizations and more deaths are expected in the coming days and weeks."

Fiction: If I get the flu vaccine, I am protected against all kinds of flu virus.

Fact: The flu vaccine varies from year to year, and each year the developers of the vaccine target the predominant strains. This means that you are reasonably well protected, but you can still get a less common strain of the flu. This year, because of the H1N1 flu, there will be two separate vaccines. The first one, which is currently being shipped out and will be available very soon, is the one that comes out every year, geared toward the "old" flu viruses that make up the seasonal flu. The second vaccine is specifically for H1N1, and will not be available until later in the year and will come out sometime in October. The H1N1 vaccine will be given in two doses, about a month apart. If you have a small child, this is the same way that the regular flu vaccine is given the first time your child gets the vaccine. This is because the first shot may not provide complete immunity when your immune system has never seen the virus (dead or alive) before. The second shot gives your immune system a second chance to get things figured out so that you will be better protected. The only time you need to get the vaccine in two doses is the first year you get the vaccine.

Who should get the vaccine?

In the event of a limited vaccine supply, the following groups receive the vaccine before others: pregnant women, people who live with or care for children younger than 6 months of age, health care and emergency medical services personnel with direct patient contact, children 6 months through 4 years of age, and children 5 through 18 years of age who have chronic medical conditions. Once the demand for vaccine for these target groups has been met at the local level, programs and providers should begin vaccinating everyone from ages 25 through 64 years. (From the CDC: http://www.cdc.gov/h1n1flu/vaccination/public/vaccination_qa_pub.htm)

Here is the email that was sent out at work, by the Infection Control Officer of the hospital:

As there is growing concern regarding the upcoming influenza season and the current novel influenza A (H1N1) pandemic, I wanted to provide a brief update on the situation.

∙ The influenza season in the southern hemisphere appears to be winding down, with most countries having past the peak level of influenza activity. Novel influenza A H1N1 was and is the dominant circulating influenza strain, supplanting seasonal influenza A. The disease spectrum appears to be similar to what has been seen in North America.

∙ In the US, influenza activity has been stable over the summer, with most states currently reporting local or sporadic activity. Novel influenza A (H1N1) is causing the majority of influenza in the United States, and is expected to be the predominant cause of influenza this fall and winter.

∙ In the United States, most of the persons affected have been younger than 50 years old. Symptoms have included fever, cough, and sore throat in the majority. About 25% of infected persons have presented with diarrhea or vomiting. Most disease continues to be mild and self-limited.

∙ The rapid influenza test is an insensitive test for novel influenza A (H1N1). A negative test does NOT rule out infection.

∙ H1N1 PCR testing (in Colorad0) from the state health department is only being done for hospitalized patients, in order to better understand the epidemiology of the virus, rather than as a diagnostic tool.

What this means:

∙ A person with sudden onset of fever, cough, sore throat and other flu-like symptoms such as muscle aches and headache should be considered to have novel influenza A (H1N1) if there is not another probable explanation.

∙ Every person suspected to have influenza should be treated as if they have influenza until proven otherwise, and be placed in the appropriate isolation precautions. If influenza testing is ordered, the person tested should be considered to have influenza until proven otherwise.

∙ Antiviral medications are available for treatment and chemoprophylaxis. However, most people with influenza do not require antiviral therapy. Antiviral prescription is appropriate for persons with severe illness and those at high-risk of complications of influenza (http://www.cdc.gov/h1n1flu/recommendations.htm). If appropriate, antiviral therapy should be prescribed based on clinical suspicion, not on testing results. Healthcare providers with unintended, unprotected, close contact to a patient with influenza may be offered chemoprophylaxis to prevent infection.

I hope the email above was informative. Other random tips:

If you are coughing, cough into your elbow, not your hands. This applies whether you have the flu or not.

Wash your hands frequently with soap and water.

Don't spit on the ground if you cough up phlegm. This releases your personal "bugs" (viruses, bacteria, etc) into the environment around you and exposes your fellow citizens to your illness.

If you have the flu, stay home until you are well. It's best not to expose anyone else unnecessarily.

Use the sanitizing wipes on your grocery cart and hands before you start your shopping to minimize transmission of anything you may be carrying.