We are in the midst of the flu season, and it appears that this year is hitting harder than last. The good news is that the antigen selections for this year’s influenza vaccine appear to match the most common isolates, so people who took the influenza vaccine are better protected this year.
Unfortunately, the level of protection from the flu vaccine is still less than 100%, many people remain unvaccinated, and multiple other viruses also cause influenza-like illness. For reasons mentioned above, it’s not surprising that many people who are experiencing influenza-like illness (ILI) are turning to HealthTap for help.
- An ILI has the syndrome of fever >101 °F, cough or sore throat and generalized symptoms such as malaise or myalgia, plus the lack of any other explanation for these symptoms. Sudden onset and illness of <7 days duration is more predictive of influenza.
- The classic sudden onset of high fever, chills, dry hacking cough, sore throat, rhinitis, and myalgias is highly suggestive of influenza, but individual cases are impossible to distinguish with confidence from other viral respiratory infections.
- During your evaluation of patients with ILI, be aware that healthy people can develop more severe viral pneumonitis, or other complications such as otitis and sinusitis. There is an increased chance of bacterial pneumonia (especially staph pneumonia) 1-2 weeks after onset of influenza, so look carefully at anyone whose cough or shortness of breath is present more than 10 days after onset of illness. Refer patients who appear dyspneic or more significantly ill for an in-person evaluation.
For suspected new onset of influenza, it’s not necessary or helpful to obtain nasal or throat swabs (for viral or strep cultures or influenza RT-PCR) prior to treatment. For detecting influenza, nasal swabs are better than throat swabs, but rapid diagnostic influenza tests have low sensitivity. Thus, a negative test should not be relied on – especially during active flu season.
- Consider antiviral treatment for anyone at higher risk of complications, such as those with COPD, CHF, conditions causing immunosuppression or simply age > 65 or infants <1 yr old, regardless of time since onset*.
- Current strains of influenza are >99% susceptible to both Oseltamivir (Tamiflu) and zanamivir (Relenza). Influenza resistance to the adamantanes (amantadine, rimantidine) is very high (>92% last year).
- Don’t forget to remind your patients of good hygiene as a means to limit spread, especially hand washing and limiting skin to skin contact.
- Encourage your patients and their family members to get vaccinated now if they haven’t already. It’s not too late to gain protection this season!
- In cases of uncomplicated ILI, there is no role for antibiotics for treatment or prophylaxis.
Sore throat: Could it be strep?
- Isolated sore throat without fever does not require either throat swab or treatment, unless there is documented contact with proven strep pharyngitis.
- Sore throat after documented exposure to culture-proven strep pharyngitis warrants empiric antibiotic treatment.
- You can ask patients with sore throat to take a photo of the back of their throat using their cell phone camera with the flash on. Mothers or a helper can use the handle of a fork if needed to get the tongue out of the way for the photo.
- Patients with sore throat and fever but no cough, myalgia or arthralgia should be evaluated for strep pharyngitis. In the presence of tender cervical adenopathy, and visible purulent pharyngeal exudate, empiric antibiotic therapy after a virtual consult is reasonable. In the absence of exudate or adenopathy, a referral to a PCP or urgent care for rapid strep test is the best course.
Recommended oseltamivir (Tamiflu) regimens for adults include:
Oseltamivir 75mg bid x 5 days (treatment) or 75mg qd x 10 days (chemoprophylaxis after exposure)
<1 yr, 3 mg/kg po bid x 5 days
<15 kg, 30 mg po bid x 5 days
<23 kg, 45 mg po bid x 5 days
<40 kg, 60 mg po bid x 5 days
Chemoprophylaxis is the same dosage delivered once daily for 10 days.
The attenuated live virus inhaled vaccine (Flumist) is not recommended or available this year.
The trivalent influenza vaccine for 2016-2017 contains Influenza A antigens from H1N1(California), H3N2(Hong Kong) and Influenza B antigens from Brisbane(Victoria lineage). Quadrivalent vaccines add antigens from Influenza B Phuket (Yamagata lineage)
* CDC recommends influenza antiviral treatment for:
- anyone <2 yrs or >=65 yrs,
- women who are pregnant or postpartum (within 2 weeks after delivery);
- persons with chronic pulmonary (including asthma), cardiovascular (except hypertension alone), renal, hepatic, hematological (including sickle cell disease), metabolic disorders (including diabetes mellitus) or neurologic and neurodevelopment conditions (including disorders of the brain, spinal cord, peripheral nerve, and muscle such as cerebral palsy, epilepsy [seizure disorders], stroke, intellectual disability [mental retardation], moderate to severe developmental delay, muscular dystrophy, or spinal cord injury);
- persons with immunosuppression, including that caused by medications or by HIV infection;
- persons aged <19 years who are receiving long-term aspirin therapy;
- American Indians/Alaska Natives;
- persons who are morbidly obese (i.e., BMI ≥40);
- and residents of nursing homes and other chronic-care facilities.