What Geriatric Care Providers Should Know About the 2014-2015 Flu Season

Influenza accounts for significant morbidity and mortality among older adults. According to the most recent data from the Centers for Disease Control and Prevention (CDC) for the 2014-2014 flu season, the highest rate of influenza-associated hospitalization is among adults aged 65 years and older, at approximately 38.3 per 100,000 compared to 9.7 per 100,000 in the general population. As adults aged 65 years and older are more susceptible to the infection and its complications due to a weakened immune system, the CDC strongly recommends that all older adults and healthcare personnel in long-term care settings receive an annual flu vaccine. Annals of Long-Term Care: Clinical Care and Aging^® (ALTC ) had the opportunity to discuss the current flu season with medical epidemiologist Fiona Havers, MD, MHS, Influenza Division, National Center for Immunization and Respiratory Disease, CDC. Havers also discusses current vaccination options and other guidelines pertinent to older adults.

ALTC: Which flu vaccines are available in the United States for the 2014-2015 flu season?

Havers: There are a number of relatively new vaccines available. Traditional flu vaccines that protect against three different flu viruses (ie, trivalent vaccines) are available again this season; many different manufacturers make these traditional vaccines (also called inactivated influenza vaccines, trivalent, standard dose [IIV3, standard dose]). In addition, flu vaccines made to protect against four different flu viruses (ie, quadrivalent vaccines) are also available (IIV4, standard dose). In addition to these standard-dose vaccines, a high-dose trivalent flu shot is available for people aged 65 years and older (IIV3, high dose). For adults, the CDC does not recommend one vaccine over another. The important thing is to get a flu vaccine every year.

There are several other options for specific groups younger than 65 years of age. There is a trivalent standard-dose intradermal flu shot, which is injected into the skin instead of the muscle and uses a much smaller needle, which is approved for people aged 18 to 64 years. A standard-dose trivalent shot-containing virus grown in cell culture is approved for people aged 18 years and older.

There are a few vaccines that are not recommended for older adults, including the recombinant vaccine FluBlok, which is egg-free and approved for people aged 18 through 49 years of age, and the quadrivalent live attenuated vaccine Flumist, which is delivered as a nasal spray and approved for people aged 2 to 49 years, and which is recommended preferentially for healthy children 2 years through 8 years old when immediately available and there are no contraindications or precautions.

Which flu viruses does this season’s vaccine protect against?

In trivalent influenza vaccines, this season’s vaccine provides protection against an influenza A (H1N1) virus, an influenza A (H3N2) virus, and one influenza B. Quadrivalent vaccines protect against the same three viruses as in the trivalent vaccine and an additional influenza B virus.

In August, the US Food and Drug Administration (FDA) approved the use of a jet injector device for delivering the trivalent influenza vaccine Afluria in persons aged 18 to 64 years of age. Since there are younger patients in long-term care settings who may be considered for this delivery option, what should providers know about the device’s safety and efficacy?

Jet injectors use a high pressure stream of fluid instead of a hypodermic needle to penetrate the skin. One such device was recently approved for delivery of one particular flu vaccine (Afluria by bioCSL Inc) in those 18 through 64 years of age. Clinical trial data used in the FDA’s approval demonstrated that vaccination using this jet injector method provided a non-inferior level of immune protection compared to the same flu vaccine administered via traditional flu shot.

There have been reports that this year’s vaccine is less effective because the most common strain—influenza A H3N2—has “drifted” from the target strains that were included in this year’s formulation. What should healthcare providers and older patients understand about the impact of the “drift” effect on this year’s flu season?

It’s not possible to predict with certainty which flu viruses will predominate during a given season, and flu viruses are constantly changing (called “antigenic drift”). They can change from one season to the next or they can even change within the course of one flu season. Experts must pick which viruses to include in the vaccine many months in advance in order for vaccine to be produced and delivered on time, and the current year’s vaccine components were selected back in February 2013 based on the information about circulating strains at that time. Unfortunately, now more than half of the H3N2 viruses circulating this season have drifted from the H3N2 vaccine virus component. It’s possible that vaccine effectiveness against these viruses may be reduced. However, we still recommend vaccination. Influenza vaccination still offers the best protection we have against seasonal flu. Seasonal influenza vaccination can sometimes induce antibodies and/or T cells capable of cross-reacting with viruses that are different from those in the vaccine, offering some protection, and the vaccine also has protection against H1N1 and influenza B viruses.

In light of the “drifted” H3N2 virus from which patients may not be protected, the CDC has been advising physicians to prescribe antiviral medications to patients with flu-like symptoms without waiting to confirm an influenza diagnosis. Why?

In any flu season, vaccine effectiveness is not 100%, and people can still get influenza even if they were vaccinated. The chances of this occurring may increase in a year such as this one when there is not a good match between the vaccine and a circulating influenza strain. Because influenza vaccines may be less effective this year, the use of influenza antiviral drugs as a second line of defense against the flu becomes even more important; patients with flu-like symptoms who are at high risk for complications from influenza should be treated promptly with antiviral medications regardless of whether or not they were vaccinated.

Does this recommendation apply to all patients showing flu-like symptoms, or only in certain high-risk groups?

This recommendation is only for patients that are at high risk for complications from influenza, such as hospitalization. However, everyone aged 65 years and older is considered at high risk, as are infants and children younger than 5 years, pregnant women, and adults and children with chronic medical conditions like as asthma, diabetes, and heart disease. Also, anyone who has severe, progressive, or complicated influenza or who is hospitalized for influenza—regardless of whether they are in a high-risk group—should also receive antiviral treatment.

Treatment also can be considered, on the basis of clinical judgment, for outpatients with uncomplicated influenza who are not known to be at increased risk for developing severe or complicated illness if antiviral treatment can be started within 48 hours of illness onset. Those with influenza who present with an uncomplicated febrile illness typically do not require treatment unless they are at higher risk for influenza complications, but early empiric antiviral treatment of these patients also might provide benefit (eg, a shortened duration of illness).

What are some important reminders about administering antiviral medication to adults aged 65 years and older?

As always, people who are at high risk for influenza complications should see a healthcare professional promptly if they get flu symptoms, even if they have been vaccinated this season. It’s also especially important to get antiviral medicines quickly—they work best when you start them within 2 days of the beginning of flu symptoms. However, antiviral treatment might have some benefits in patients with severe, complicated, or progressive illness and in hospitalized patients when started after 48 hours of illness onset. Decisions about starting antiviral treatment should not wait for laboratory confirmation of influenza. A summary of antiviral recommendations for clinicians is available on the CDC website at bit.ly/CDC_AntiviralMeds.

In Morbidity and Mortality Weekly Report in August, the CDC cited a recent case-controlled study in Spain that showed vaccine effectiveness declined as the time from vaccination increased in adults aged 65 years and older (bit.ly/MMWR_ACIP_Flu14-15). What should patients and clinicians understand when interpreting the findings of this study? Does timing of vaccine administration matter in the geriatric patient population?

This study suggested that during the season, protection from the influenza vaccine may have declined over the course of an influenza season. However, changes in the circulating viruses and methodologic issues might also have influenced the findings reported in this study. We know that antibody levels induced by vaccine do not substantially decline during an influenza season, however, they do decline by the next year. Although it is possible that delaying vaccination until later in the season might permit greater effectiveness later in the season, deferral might result in missed opportunities to vaccinate or vaccinating after influenza virus circulation begins.

Healthcare providers should balance maximizing likelihood of persistence of vaccine-induced protection through the season with avoiding missed opportunities to vaccinate or vaccinating after influenza virus circulation begins. Vaccination optimally should occur before the onset of influenza activity in the community, and healthcare providers should offer vaccination soon after the vaccine becomes available (preferably by October).

So is it considered too late for healthcare personnel and elderly patients to get vaccinated?

No. If someone hasn’t received the influenza vaccine yet and influenza viruses are still circulating (which they are in January), providers should still encourage healthcare personnel and elderly patients to get vaccinated.