H1N1 (Swine) Flu

Influenza H1N1, initially called “swine flu,” is a new flu virus that began circulating and causing influenza earlier in 2009. Since it is a new flu virus, large segments of the population have not been infected with the virus before, and therefore are at risk for getting infection from this strain of influenza. 

There has been a lot of attention to this virus mainly because it is new and we are uncertain how severe the illness will be among those who get the virus. To date, most of the people who have been infected with H1N1 flu have had mild clinical illness and have recovered without requiring therapy.

Frequently Asked Questions on H1N1 Flu

• Why is the H1N1 virus sometimes called “swine flu?”
• Will the seasonal influenza vaccine also protect me against H1N1?
• When is it expected that the H1N1 flu vaccine will be available?
• Are there side effects of the H1N1 flu vaccine?
• Has anyone ever been vaccinated against swine flu?
• If I was vaccinated against swine flu in 1976, am I protected?
• Can the seasonal vaccine and the novel H1N1 vaccine be given at the same time?
• If I am pregnant, should I receive both flu vaccines?
• Will vaccination against the new H1N1 flu be mandatory?
• Who will be recommended as priority groups to receive the H1N1 flu vaccine?
• Who should not receive either of the flu vaccines?
• Where can I get the flu vaccine(s)?

Why is the H1N1 virus sometimes called “swine flu?”
This virus was originally referred to as “swine flu” because laboratory testing showed that many of the genes in this new virus were very similar to influenza viruses that normally occur in pigs (swine) in North America. But further study has shown that this new virus is very different from what normally circulates in North American pigs. It has two genes from flu viruses that normally circulate in pigs in Europe and Asia and bird (avian) genes and human genes. Scientists call this a "quadruple reassortant" virus.

Will the seasonal influenza vaccine also protect me against H1N1?
No, the seasonal influenza vaccine will only offer protection against the more typical strains of influenza.

When is it expected that the H1N1 flu vaccine will be available?
Additional doses of the H1N1 flu vaccine are expected to be available in the later part of the fall/early winter. More specific dates cannot be provided at this time as vaccine availability depends on several factors. Making a vaccine is a multi-step process that takes several months to complete.

Are there side effects of the H1N1 flu vaccine?
As with seasonal influenza, one may get mild pain at the injection site, may get a mild and short-lived fever (24 – 48 hours) and also may feel fatigued for approximately 24 hours. Historically there was concern of a more serious side effect called Guillian-Barré syndrome (GBS). This is a neurologic condition that can cause progressive paralysis in those who have the syndrome. It was suggested that people may have been slightly more likely to get GBS after they had received the H1N1 flu vaccine in 1976. It is currently unclear if this past H1N1 flu vaccine actually caused a higher than normal rate of GBS after vaccination. It is also important to remember that one of the most frequent causes of GBS is viral infection itself (including flu), so getting the flu vaccine may actually protect people from getting GBS because they are less likely to get the actual infection after they have received the vaccine. 

Has anyone ever been vaccinated against swine flu?
Yes, in 1976 there was a swine flu outbreak at Fort Dix in New Jersey. Many Americans were vaccinated at that time. 

If I was vaccinated against swine flu in 1976, am I protected?
Older adults might have some pre-existing immunity to H1N1 (swine) flu, according to the CDC. Lab tests showed that some adults, particularly those older than 60, had antibodies against the new strain, but the CDC cautioned that it is not known what this will mean in terms of actual immunity or clinical protection.

Can the seasonal vaccine and the H1N1 flu vaccine be given at the same time?
The seasonal flu and H1N1 flu vaccines could be administered on the same day so long as both vaccines are not in the nasal spray format.

If I am pregnant, should I receive both flu vaccines?
Yes. Pregnant women are a high risk group for complications from all flu strains, and thus should get both flu vaccines. The flu vaccine is safe during pregnancy and also offers protection to newborns for the first six months of life (this is important because newborns are not candidates to receive the flu vaccine even though they are at a higher risk of complications from flu). So if the mom gets the flu vaccine, she is not only protecting herself but also her newborn child. 

Will vaccination against the new H1N1 flu be mandatory?
No. CDC and ACIP (Advisory Committee on Immunization Practices, which provides advice and guidance on the control of vaccine-preventable diseases) will make recommendations for who should receive H1N1 flu vaccine, and state and local health departments and institutions will determine how to implement these recommendations. If the vaccine is recommended for use, those who choose vaccination for themselves or their children will be screened for contraindications to vaccination (such as an allergy to eggs ) and will receive information sheets describing the vaccine’s risks and benefits, possible adverse events associated with vaccination, and how to report these events.

Who will be recommended as priority groups to receive the H1N1 flu vaccine?
CDC’s Advisory Committee on Immunization Practices (ACIP) has recommended that certain groups of the population receive the H1N1 flu vaccine when it first becomes available. These key populations include:

• pregnant women
• people who live with or care for children younger than six months of age
• health care and emergency medical services personnel
• people between the ages of six months and 24 years old
• people ages of 25 through 64 years of age who are at higher risk for novel H1N1 because of chronic health disorders or compromised immune systems

Who should not receive either of the flu vaccines?
Some people should not be vaccinated without first consulting a physician. They include:

• people who have a severe allergy to chicken eggs
• people who have had a severe reaction to an influenza vaccination in the past
• people who developed Guillian-Barré syndrome (GBS) within six weeks of getting an influenza vaccine previously
• children less than six months of age (Influenza vaccine is not approved for use in this age group)
• people who have a moderate or severe illness with a fever should wait to get vaccinated until their symptoms lessen

Where can I get the flu vaccine(s)?
Seasonal influenza vaccine will likely be available in a combination of settings such as vaccination clinics organized by local health departments, health care provider offices, schools, and other private settings, such as pharmacies and workplaces. H1N1 flu vaccine will be distributed to every state and each state's Department of Health will develop a vaccine delivery plan. Once H1N1 flu vaccine is distributed throughout Pennsylvania, local plans can be made for distribution that will likely parallel seasonal flu vaccine plans.

More information about the H1N1 virus can be found on the Centers for Disease Control (CDC) website.