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HIV clinicians and patients should prepare now for fall pandemic flu
Recent novel H1N1 flu outbreak offers lessons
By early May it appeared that the novel H1N1 influenza outbreak was beginning to ebb and worst-case scenarios would be averted. But the outbreak highlighted at least one big uncertainty in our response to what nearly was labeled a worldwide flu pandemic: How would HIV/AIDS patients respond to an infection of a new influenza virus?
"H1N1 is a neoantigen, and HIV patients can have difficulty mounting responses to neoantigens," says Cliff Lane, MD, clinical director, National Institute of Allergies and Infectious Diseases (NIAID) of the National Institutes of Health (NIH).
"We know how well an HIV-infected person handles seasonal flu, but this is the first time we've had anything like this, and it's the first time we're seeing this since the HIV epidemic began," Lane says.
The other big unknown is what will happen with this virus in the fall and winter when flu season returns.
"Flu is remarkably unpredictable, and it mutates rapidly," says John T. Brooks, MD, a medical epidemiologist who leads the HIV clinical epidemiology team at the Centers for Disease Control and Prevention (CDC) in Atlanta, GA.
Influenza epidemic history has taught infectious disease experts that the influenza virus generally takes one of two routes: "There's genetic drift, and it changes a little and a little more," Brooks says. "Or there is a major shift, and a whole new influenza appears, and the population doesn't have immunity because we haven't seen this one before."
Before the 2009 H1N1 flu, there were three significant flu pandemics within the past century. (See flu pandemic timeline.)
It's the potential of a repeat of the 1918 flu which quickly struck and killed tens of millions worldwide that most worries public health officials. The 2009 flu virus is not like that one, however.
"To the extent they've looked at it in the lab, this strain of H1N1 doesn't have the same virulent markers as the strain of 1918," Brooks says.
However, it has the potential to infect a large percentage of people because of its novelty. Seasonal flu typically has a clinical attack rate of 5% to 15%. Influenza pandemics, by contrast, have a clinical attack rate of 25% to 50%.
"It's one we haven't been exposed to before," Brooks says. "What it means is a larger fraction of the population is at risk for infection."
For HIV clinicians and their patients, this suggests a policy of caution when the influenza season returns.
"Flu is a pretty unpredictable virus, and we'll have to watch and see what happens," Lane says. "All we can do is to prepare for the worst."
What this means for HIV clinicians and patients is they should not take any chances this upcoming flu season and take the precautions that are always recommended, but not always followed.
"We'd make the same recommendations for people to prepare themselves as they would for any flu season," Brooks says.
For example, HIV patients should be vaccinated against influenza infection. While it's not clear when a vaccine will be available for the new strain, they should take both that vaccine and the regular flu vaccine as soon as they are distributed, he says.
HIV patients should receive the inactive vaccine, not the live, attenuated vaccine, Brooks adds.
"We don't recommend the live vaccines for HIV patients," he says.
"I also would encourage all of the doctors, nurses, and health care providers who have contact with HIV patients to be vaccinated, as well," Brooks says.
"HIV patients should be taking the usual precautions to prevent getting an infection, and these include washing hands and covering your cough if you get ill," he says. "People with HIV need to be particularly vigilant for signs and symptoms of infection."
Health care officials believe that HIV patients are not any more predisposed to becoming infected with seasonal flu than are other people, Brooks notes.
"But once they're infected, a person with HIV/AIDS who has influenza might experience a somewhat more prolonged or severe force of disease," he says. "They could have a longer hospitalization, and that's what we want to avoid."
So HIV patients and their clinicians should be vigilant to the signs and symptoms of infection, including cough, sore throat, diffused muscle aches, headache, fever, and in some cases in Mexico this spring, there were gastrointestinal symptoms, including diarrhea, Brooks says.
Also, it would be a good policy for HIV clinicians to advise patients to stay away from the clinic or doctor's office if they suspect they have the flu, he notes.
"Sometimes you can be assessed for the flu over the phone," Brooks says. "To the extent that doctors can use email and telephone calls to contact patients, that would reduce the risk that if the person has influenza that he brings other patients into contact with it."
If patients do come into the clinic due to flu symptoms, then they should be asked to wear a mask, he adds.
Also, flu treatment should be started within 48 hours of symptoms appearing. The available evidence suggests that HIV patients can take the flu drugs while being treated with antiretrovirals, and there are no drug-drug interactions.
Public health officials have determined that two flu drugs effectively fight the new H1N1 strain, and these are oseltamivir (Tamiflu®) and zanamivir (Relenza®).
"We recommend prophylaxis use [of oseltamivir and zanamivir] only for persons with close contact with a confirmed probable case," Brooks says. "You might want to consider prophylaxis if you're at home, and you have HIV, and your kid goes to school and has influenza symptoms after a class of kids went to Mexico, and one was a confirmed case."
But HIV clinicians should encourage patients to not overreact and ask for Tamiflu if they were on the subway and someone coughed on them, Brooks says.
"We do not recommend prophylaxis when there are only suspected cases," he adds.
Another consideration is how to handle time off from work or school and quarantine in the event of a pandemic flu.
"People with HIV infection might want to think about what they would do if they had to take one to two weeks off of work," Brooks says.
"They would need to be adherent to their antiretroviral therapy (ART) and take care of themselves to stay healthy," he adds. "They should always be adherent to following their medication regimen, and particularly now it's important because they need to concentrate on keeping their immune system as healthy as possible."
HIV patients also should consider volunteering to enroll in clinical trials involving influenza vaccines and treatment, Brooks and Lane say.
"I'm quite sure they'll be testing the [new H1N1 flu] vaccine in HIV patients," Lane says.
"Typically speaking you do initial studies in healthy volunteers, and then you do additional studies in people you think have altered immune responses," he adds.
"We always welcome HIV-infected persons to volunteer to participate in clinical trials," Brooks says.
They could find out more about which trials are available by visiting the Web site: www.clinicaltrial.gov and searching for "influenza," he suggests.
Researchers don't have a lot of good data on HIV-infected persons with influenza, Brooks notes.
"We need more information," he adds. "And during this outbreak, they're looking to see if people who are immunocompromised are at greater risk with the experience."