Ask a Pharmacist: Gearing Up for Flu Season
It’s Friday. You’ve had a long, stressful week at work and you’re looking forward to going home and relaxing. As you’re making dinner, you notice you have very little energy all of a sudden. In fact, your muscles are feeling a little achy. You decide to take your meds and go to bed. In the middle of the night, you wake up with muscle aches, a sore throat, a headache, and a fever. “Uh-oh,” you wonder, “should I have gotten a flu shot?”
“Flu” is short for “influenza.” Just as with rhinoviruses, which cause the common cold, there are different types of influenza viruses that circulate during flu season, which typically begins in October, peaks in January or February, and ends by May.
The three major flu types are labeled A, B, and C. Influenza C is not thought to cause serious illness; types A and B cause yearly epidemics of flu. New strains of influenza A arise regularly, which means new vaccines must be developed yearly to combat the evolving virus.
Influenza A carries two important proteins—hemagglutinin (H) and neuraminidase (N)—that help identify these different strains. For example, the strain that caused the “swine flu” outbreak in 2009 was a new type of H1N1, a flu strain that carried hemagglutinin type 1 and neuraminidase type 1 in a novel combination.
The flu often feels like it comes on very suddenly. You may experience fever, fatigue, sore throat, muscle aches, headaches, congestion, and cough. Symptoms of the flu are usually more severe than symptoms of a cold. Unfortunately, almost everyone will get the flu at least once in their lifetime.
HIV and the Flu
People living with HIV/AIDS may be more susceptible to the flu. One study conducted in Canada followed a sample of 50 individuals who presented to their HIV clinic with fever and respiratory symptoms. No viral or bacterial infection could be determined in half the study sample, but 21 persons (42%) were diagnosed with influenza and only four (8%) had a non-viral infection.
People with HIV may also be at higher risk for flu-related complications, and are hospitalized with heart and lung illnesses more frequently during influenza season than during any other time of the year. The flu may also last longer for people living with HIV, and the risk of death from influenza illness is higher. A study looking at excess death rates (the number of deaths beyond what is expected in a given period of time) in the early 1990s found that influenza caused an excess death rate of 10.17 per 10,000 persons with AIDS, while the excess death rate in persons aged 65 and older was 8.54 per 10,000.
This study showed that persons with AIDS were at a higher risk, even when compared with the “elderly” U.S. population. Antiretroviral therapy has helped reduce the risk of death due to influenza in persons living with HIV, but the risk may still be higher than in the broader population.
Weighing the Risks and Benefits of the Flu Vaccine
Medical providers and researchers have worried that, by activating the immune system’s CD4 cells (the very cells HIV preferentially infects), the flu vaccine may actually trigger HIV replication and cause disease progression in people living with the virus. Some studies have demonstrated a short-lived increase in HIV replication following influenza vaccination, but other studies have had different results.
For example, one very large, definitive study published in 2000 looked at medical records for 8,007 HIV-positive individuals who received a flu shot and 11,794 who remained unvaccinated, and found no negative long-term effect of influenza vaccination on their CD4 counts or viral loads. The study also found that individuals who got the flu shot had a slightly lower risk of progression to clinical AIDS.
This study and others suggest that getting a flu shot isn’t harmful, but does the vaccine work as well for people with HIV? Measuring an individual’s influenza antibody titer—the amount of antibodies in a sample of blood—can reveal how well the body is responding and is one way to estimate a vaccine’s efficacy. Studies have found that persons with HIV tend to not mount a strong antibody response to the flu vaccine—likely because HIV reduces the number of immune system cells that help the body respond to viruses. Other factors may include high viral loads and illnesses that warrant an AIDS diagnosis.
However, measurements of antibody titers are not the only way to look at how well the vaccine works. Another approach is to look at the vaccine’s clinical effectiveness—in other words, how many people who get vaccinated actually avoid the flu?
An early study sheds light on vaccine effectiveness in HIV-positive people. In November 1996, there was an outbreak of influenza A among residents and employees at a New York residential facility for people with AIDS. Researchers calculated the flu vaccine’s effectiveness rate to be 27% in HIV-positive individuals, compared with 39% in those without HIV. Individuals who came down with the flu despite getting the vaccine felt better on average 2.5 days faster than those who were not vaccinated. Although in this study the difference in duration of illness was not statistically significant, those two and a half days probably felt significant to the folks recovering from flu.
More recent data are limited regarding flu vaccine effectiveness among HIV-positive people. A 2008 meta-analysis of four studies reported a pooled “relative risk reduction” of 66% among people with HIV who were vaccinated against the flu. However, the authors noted, the meta-analysis included only one randomized controlled trial, and that study yielded a more conservative estimate of 44%. “There is an urgent need for randomized trials to guide policy and clinical practice,” the authors stated.
The Flu Vaccine and You
So, should you get a flu shot this year? The U.S. Centers for Disease Control and Prevention (CDC) recommends that, with some exceptions, all HIV-positive people get their flu shot yearly as the best known way to protect against influenza infection.
Some people, however, should not be vaccinated. You should not get a flu shot if you’ve ever had an allergic reaction to a vaccine, if you are allergic to eggs (because chicken eggs are used in the manufacturing process), or if you have a history of any paralyzing illnesses such as Guillain-Barré syndrome. Also, if you are already experiencing symptoms of a fever or a cold, wait until you feel better before getting a flu shot.
People living with HIV should seek a “traditional” (injected) flu shot, which contains only inactivated influenza virus. The influenza nasal vaccine FluMist is a “live” vaccine that is not advised for with compromised immune systems. Your medical provider’s office can offer the vaccine at your next visit. In many cases your local community pharmacy has trained pharmacists who can also give you a flu shot.
How else can you help avoid getting or spreading the flu this year? The CDC offers a few tips:
- Wash your hands frequently with soap and water. Use an alcohol-based hand rub if soap and water aren’t available.
- Avoid touching your eyes, nose, and mouth. The flu virus and other germs get in—and out—this way.
- Cover your nose and mouth with a tissue when you cough or sneeze, then trash the tissue. (No tissues handy? Cover your cough or sneeze with your sleeve, not your bare hand.)
- While you are sick, do your best to limit contact with others to keep from spreading the flu.
What To Do If You Get the Flu
The CDC advises people with HIV to start treatment early if they come down with a case of the flu. Two prescription antiviral drugs have been approved by the U.S. Food and Drug Administration and are CDC-recommended to treat influenza: oseltamivir (brand name Tamiflu) and zanamivir (brand name Relenza).
Tamiflu comes in pill and liquid form, and Relenza is a powder that is inhaled. Both are typically used for five days. Antiviral treatment for flu works best when started within two days of getting sick, but starting them later can still help reduce the duration and severity of flu symptoms.
Relenza should not be used if you are allergic to milk proteins or have ongoing airway diseases such as asthma or chronic obstructive pulmonary disease (COPD). Tamiflu and Relenza have no known interactions with antiretroviral medications.
Over-the-counter pain relievers like acetaminophen (such as Tylenol) and ibuprofen (Advil or Motrin, for example) can help relieve fever, muscle aches, and throat soreness. Your medical provider can also recommend non-prescription decongestants and cough remedies to ease other uncomfortable symptoms of the flu.
Also, be sure to get plenty of rest, and stay hydrated by drinking water, clear broth, or electrolyte drinks or sports drinks.
And remember, your medical team—including your pharmacist—is there to answer your questions and help you get well soon!
Jennifer Cocohoba, PharmD, is an associate clinical professor in the School of Pharmacy at the University of California, San Francisco (UCSF). Since 2004, she has worked as the clinical pharmacist for the UCSF Women’s HIV Program, where she provides adherence support and medication information to patients and providers.
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