The H1N1 virus, referred to as “swine flu,” is a relatively new influenza virus that is causing illness in humans around the globe. It was first detected in the United States in the spring of 2009 and was initially thought to be similar to a virus occurring in pigs in North America (hence the name swine flu); but further study has shown that the H1N1 virus is very different from what normally circulates among North American pigs. It has two genes from flu viruses normally found in pigs in Europe and Asia, but it also has avian genes and human genes; in other words, it is a “mixed-bag” virus, referred to as a “quadruple reassortant” virus. The new term for swine flu, novel H1N1 is 2009 Influenza A (H1N1).

We know that the H1N1 virus is contagious, but at this point we don’t know just how easily transmissible it is among humans. It was first identified in the United States in cases in Texas and California. An updated United States case count of H1N1 (swine) flu is kept by the Centers for Disease Control (CDC).

The symptoms of 2009 Influenza A are similar to those found in regular seasonal flu: fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills, fatigue, and in some reported cases diarrhea and vomiting. Like the seasonal flu, the symptoms of H1N1 flu can be relatively mild, moderate, severe, or even fatal. The at-risk population includes children under the age of five, pregnant women, and those with a previously known health complication (such as asthma or diabetes). Interestingly, people over the age of 64 do not appear to be at increased risk for complications from H1N1, and one-third of people over age 60 may have some antibodies to the H1N1 virus. We don’t yet know whether these antibodies will offer any protection against the current H1N1 virus.

Each year in the United States, an average of 36,000 people die and 200,000 people are hospitalized from seasonal flu-related causes. Of course, there have not been anywhere near that many deaths to date from H1N1. So why all the worry? The CDC is still learning about the severity of this novel flu virus and does not yet have enough information to predict how severe the next outbreak will be. So we proceed cautiously.

How does the H1N1 virus spread? We believe that it passes from an infected individual in the same way that the seasonal flu virus is spread. That is, a contaminated person can spread the disease by coughing or sneezing. Additionally a disease-free person can contract the disease by touching something that has been contaminated by someone with influenza and then touching his own mouth, nose, or eyes. Current thinking is that an individual can be contagious for one day before developing symptoms and perhaps for seven days (or more) after getting sick.

This leads to prevention. Since spread is from contact, here are some general recommendations

Cover your nose and mouth with a tissue if you sneeze or cough; then dispose of the tissue in a trash can.

Wash your hands often with soap and water or an alcohol-based hand sanitizer.

Avoid touching your face. Try to avoid contact with sick people.

If you are sick, stay home for seven days after your symptoms begin or until you have been symptom-free for 24 hours, whichever is longer

Pay attention to public health advisories and closure of schools or public events.

Plan ahead: have a week’s supply of medication, food, and water in the house for every member of your family (pets included). Keep a supply of OTC medication for relief of flu symptoms, so that if you come down with the flu, you don’t need to go out into the public and expose your neighbors.

If you are sick and must go out in public, cover your face with a mask. If you must go near an infected person, you can also wear a mask to minimize your own exposure. The preferred type of mask is an N-95. Remember to secure the mask tightly over your nose and around your mouth.

The last piece of the swine flu or 2009 Influenza A puzzle involves the H1N1 flu vaccine. The virus needed to make this vaccine is not growing fast enough in the labs to produce enough vaccine in time for fall. Most likely the supplies will be inadequate, and two shots may be needed for proper coverage – a priming first dose and a booster shot several weeks later. Both live, attenuated and inactivated vaccines will be produced. As with seasonal flu vaccine, neither of these will contain adjuvants (an additive to a drug intended to increase its potency or effectiveness). However adjuvants are being examined for use in future H1N1 vaccines. The use of adjuvants will need to be approved under an Emergency Use Authorization, so keep checking the CDC site if you are interested in what type of vaccine is available. With supplies being low, initial shots will go to healthcare workers and to the most at-risk patients. So this might be a good time to go back and read the prevention suggestions again.