Is the H1N1 Vaccine for You?

An outbreak of H1N1 influenza A virus infection was initially identified in Mexico in late March 2009. Within a few months, the World Health Organization (WHO) had raised the H1N1 flu to its highest alert status—indicating that it had reached widespread transmission within the community on at least two continents. The H1N1 flu (or swine flu) virus represents a combination of four strains of influenza—two from swine, one from humans and one from birds.

Unlike seasonal flu, the H1N1 flu has hit young people the hardest. By July 2009, there had been about 25 reported cases of H1N1 flu for every 100,000 people up to 24 years old. In contrast, only 1.3 persons of every 100,000 people over 65 years of age had been reported to be ill with H1N1 flu.

The signs and symptoms of H1N1 flu are similar to those of seasonal influenza, except that H1N1 victims seem to have higher rates of vomiting and diarrhea. Other symptoms include fever (at least 100 degrees), cough, sore throat, fatigue and headache. The virus is present in respiratory secretions of infected persons and is typically transmitted by sneezing and coughing. In worldwide observations, the H1N1 flu virus seems to be more easily transmitted than the seasonal flu virus. The incubation period (the time required to become ill after exposure to the virus) seems to be from one to four days. People with healthy immune systems seem to be contagious from one day before symptoms occur until the resolution of fever. Rarely, H1N1 influenza patients may require hospitalization, typically because of pneumonia or dehydration.

The best protection against the H1N1 flu is by vaccination. The seasonal flu vaccine does not provide protection against H1N1 flu, and in order to receive comprehensive protection against flu this year, you must receive both vaccines. The H1N1 vaccine is similar to the seasonal flu vaccine and, in fact, is manufactured using the same processes and facilities that are used to make the currently licensed seasonal flu vaccines. Antibodies that protect against the H1N1 flu infection develop about two weeks after vaccination.

There are two kinds of H1N1 flu vaccines being produced. The H1N1 flu shot is an inactivated vaccine which contains killed virus. The flu shot is approved for all people 6 months of age and older. The most common side effects of the shot are soreness, redness or swelling where the shot was given, low-grade fever and body aches. The H1N1 nasal spray flu vaccine is made with live, weakened viruses that do not cause the flu. The nasal spray is only approved for use in healthy people 2 years to 49 years of age who are not pregnant. The most common side effects are runny nose, headache, sore throat and cough.

Initial target groups for vaccination are pregnant women, people who live with or provide care for infants younger than 6 months, health care and emergency medical services personnel, people 6 months through 24 years of age, and people 25-64 years of age who have certain high-risk medical conditions. Once the target groups have been vaccinated, the CDC recommends that all people from 25-64 years of age get vaccinated. The lowest priority group is people over 65 years of age because they seem to have the lowest risk for contracting the H1N1 flu.

Treatment is available for illness due to H1N1 flu, and will most likely be of benefit when begun within the first 48 hours of illness. Testing for H1N1 flu is available but is not necessary to make the diagnosis and begin treatment.

Dr. Kelly McMahon, a graduate of Yale University and the University of Pittsburgh School of Medicine, is board certified in Internal Medicine. She is a member of the American College of Physicians and the Allegheny County and Pennsylvania Medical Societies. She is in solo practice in the North Hills of Pittsburgh.