Dr. Claude Dharamraj, director of the Pinellas County Health Department, has been taking your questions about swine flu. See more questions and answers online at tampabay.com/swine-flu, where you also can submit your questions in the Comments area.
I got a flu shot once, and then got the flu right after. Why would I even consider getting a flu shot now?
It usually takes two weeks from the time a person receives a flu shot until he or she is immune. If someone has been exposed to the virus right before receiving the vaccine, the vaccine will not prevent them from developing symptoms. It is also important to note that there are other viruses — such as those that cause the common cold — circulating within the community that can cause respiratory symptoms similar to the flu. Allergies can also trigger similar symptoms.
Because the strain of influenza virus changes every year, it is necessary to get a flu shot annually. The vaccine is created each spring by using the components of the viruses that are expected to circulate that fall and winter. An influenza vaccination, although not a permanent vaccine, will help lower a person's chance of catching the flu each season by 80 percent.
It is possible for a person who is vaccinated to become ill with the flu if he or she is exposed to a type of flu virus that is not part of the vaccine's components. This was seen recently with the emergence of the H1N1 (swine) flu strain. Those people who do catch the flu virus despite getting their shot will likely experience fewer and milder symptoms.
I am an adult with asthma. Should I get the H1N1 vaccine?
Yes, you should consider it. Adults with asthma are at high risk of developing complications after contracting the flu. Respiratory infections like influenza are more serious in patients with asthma, and such infections can often lead to pneumonia and acute respiratory disease. Everyone with asthma from the ages of 6 months through 64 years should get the 2009 H1N1 flu shot. The live, attenuated influenza vaccine (LAIV), which is a nasal spray, is not recommended for people with asthma.
How do you test for swine flu versus seasonal flu? Is it a blood test or a smear? Do you test everyone who has flu symptoms?
A flu test is usually done by wiping a swab along the inside of a person's nostril to get secretions. One type of test, the rapid test, will indicate whether a person has the flu or not. The results are available a few minutes after the test is performed. Some commercially available rapid tests can distinguish between influenza A and B viruses. However, it is not possible to differentiate the H1N1 (swine) flu virus from seasonal influenza A viruses using the rapid test.
Real-time RT-PCR is the recommended test for diagnosing patients with the H1N1 flu. This test is performed at a laboratory and results are available in a few days. This season, the Centers for Disease Control recommends that influenza diagnostic testing be prioritized for 1) hospitalized patients with suspected influenza; 2) patients for whom a diagnosis of influenza will inform decisions regarding clinical care, infection control, or management of close contacts; and 3) patients who died of an acute illness in which influenza was suspected.
Most patients who have symptoms of influenza with no complications do not require diagnostic influenza testing for clinical management.
What's the incubation period between exposure to the virus and actually coming down with the flu?
The estimated incubation period is between one to four days, although a number of factors can affect the length of time it takes for a person to come down with symptoms.
I'm concerned for my wife because she is pregnant. Will the vaccine hurt our baby in any way?
No. According to the Centers for Disease Control, flu vaccines have not been shown to cause harm to a pregnant woman or her baby. The seasonal flu shot has been recommended for pregnant women for many years. The 2009 H1N1 flu vaccine was made using the same processes as the seasonal flu vaccine.
Although the flu shot is believed to be completely safe for both pregnant and breast-feeding women, the nasal spray flu vaccine is not recommended for pregnant women. Women who are breast-feeding can get the intranasal vaccine.
Pregnant women, even if they are healthy, are at high risk of hospitalization and death from H1N1 (swine) flu than the general population. They are four times more likely to be hospitalized, with an unusually high death rate. The influenza vaccine offers very important health benefits to mothers and babies. Additional information can be found by visiting: http://www.cdc.gov/h1n1flu/vaccination/providers_qa.htm.