Applied Evidence

Take these steps to improve your flu season preparedness

J Fam Pract. 2018 October;67(10):602-607

Author(s):

Jennifer L. Hamilton, MD, PhD, FAAFP

Nerissa L. Baptiste, MD

The 6 strategies outlined here can help you reduce the risk of illness and limit its severity if contracted.

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PRACTICE RECOMMENDATIONS

› Recommend influenza vaccination for all patients at least 6 months old unless a specific contraindication exists. A

› Recommend pneumococcal vaccination to appropriate patients to reduce the risk for a common complication of influenza. A

› Encourage hygiene-based measures to limit infection, including frequent handwashing or use of a hand sanitizer. B

› Prescribe oseltamivir to hospitalized influenza patients to limit the duration and severity of infection. B

Strength of recommendation (SOR)

A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series

References

1. CDC. Weekly US influenza surveillance report. https://www.cdc.gov/flu/weekly/index.htm. Published June 8, 2018. Accessed August 22, 2018.

2. CDC. Estimated influenza illnesses, medical visits, hospitalizations, and deaths averted by vaccination in the United States. Published April 19, 2017. https://www.cdc.gov/flu/about/disease/2015-16.htm. Accessed Setptember 18, 2018.

3. CDC. Seasonal influenza vaccine effectiveness, 2005-2018. https://www.cdc.gov/flu/professionals/vaccination/effectiveness-studies.htm. Published February 15, 2018. Accessed August 22, 2018.

4. Sah P, Medlock J, Fitzpatrick MC, et al. Optimizing the impact of low-efficacy influenza vaccines. Proc Natl Acad Sci. 2018:201802479.

5. Flannery B, Reynolds SB, Blanton L, et al. Influenza vaccine effectiveness against pediatric deaths: 2010-2014. Pediatrics. 2017;139: e20164244.

6. Kim DK, Riley LE, Hunter P. Advisory Committee on Immunization Practices recommended immunization schedule for adults aged 19 years or older—United States, 2018. MMWR Morb Mortal Wkly Rep. 2018;67:158–160.

7. Robinson CL, Romero JR, Kempe A, et al. Advisory Committee on Immunization Practices recommended immunization schedule for children and adolescents aged 18 years or younger—United States, 2018. MMWR Morb Mortal Wkly Rep. 2018;67:156–157.

8. Grohskopf LA, Sokolow LZ, Broder KR, et al. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices—United States, 2017-18 influenza season. MMWR Recomm Rep. 2017;66:1-20.

9. CDC. Influenza vaccines—United States, 2017–18 influenza season. https://www.cdc.gov/flu/protect/vaccine/vaccines.htm. Published May 16, 2018. Accessed August 22, 2018.

10. Grohskopf LA, Sokolow LZ, Fry AM, et al. Update: ACIP recommendations for the use of quadrivalent live attenuated influenza vaccine (LAIV4)—United States, 2018-19 influenza season. MMWR Morb Mortal Wkly Rep. 2018;67:643–645.

11. Jenco M. AAP: Give children IIV flu shot; use LAIV as last resort. AAP News. May 21, 2018. http://www.aappublications.org/news/2018/05/21/fluvaccine051818. Accessed August 22, 2018.

12. Glinka ER, Smith DM, Johns ST. Timing matters—influenza vaccination to HIV-infected patients. HIV Med. 2016;17:601-604.

13. Castilla J, Martínez-Baz I, Martínez-Artola V, et al. Decline in influenza vaccine effectiveness with time after vaccination, Navarre, Spain, season 2011/12. Euro Surveill. 2013;18:20388.

14. CDC. Influenza antiviral medications: summary for clinicians. https://www.cdc.gov/flu/professionals/antivirals/summary-clinicians.htm. Published May 11, 2018. Accessed August 22, 2018.

15. CDC. Pneumococcal vaccination summary: who and when to vaccinate. https://www.cdc.gov/vaccines/vpd/pneumo/hcp/who-when-to-vaccinate.html. Published February 28, 2018. Accessed August 22, 2018.

16. Jefferson T, Del Mar CB, Dooley L, et al. Physical interventions to interrupt or reduce the spread of respiratory viruses. Cochrane Database Syst Rev. 2011;(7):CD006207.

17. Loeb M, Dafoe N, Mahony J, et al. Surgical mask vs N95 respirator for preventing influenza among health care workers: a randomized trial. JAMA. 2009;302:1865-1871.

18. Dobson J, Whitley RJ, Pocock S, Monto AS. Oseltamivir treatment for influenza in adults: a meta-analysis of randomised controlled trials. Lancet. 2015;385:1729-1737.

19. Ghebrehewet S, MacPherson P, Ho A. Influenza. BMJ. 2016;355:i6258.

20. Kaysin A, Viera AJ. Community-acquired pneumonia in adults: diagnosis and management. Am Fam Physician. 2016;94:698-706.

21. Rodrigo C, Leonardi‐Bee J, Nguyen‐Van‐Tam J, et al. Corticosteroids as adjunctive therapy in the treatment of influenza. Cochrane Database Syst Rev. 2016;3:CD010406.

22. Brassard P, Wu JW, Ernst P, et al. The effect of statins on influenza-like illness morbidity and mortality. Pharmacoepidemiol Drug Saf. 2017;26:63-70.

23. Fedson DS. Treating influenza with statins and other immunomodulatory agents. Antiviral Res. 2013;99:417-435.

24. Khandaker G, Rashid H, Chow MY, et al. Statins for influenza and pneumonia. Cochrane Database Syst Rev. January 9, 2017 [withdrawn].

Last year’s influenza season was severe enough that hospitals around the United States set up special evaluation areas beyond their emergency departments, at times spilling over to tents or other temporary structures in what otherwise would be parking lots. The scale and potential severity of the annual epidemic can be difficult to convey to our patients, who sometimes say “just the flu” to refer to an illness responsible for more than 170 pediatric deaths in the United States this past year.¹ The Centers for Disease Control and Prevention (CDC) recently updated its 5-year estimates of influenza-related deaths in the United States; influenza mortality ranges from about 12,000 deaths in a mild season (such as 2011-2012) to 56,000 in a more severe season (eg, 2012-2013).²

Although influenza cannot be completely prevented, the following strategies can help reduce the risk for the illness and limit its severity if contracted.

Prevention

Strategy 1: Vaccinate against influenza

While the efficacy of vaccines varies from year to year, vaccination remains the core of influenza prevention efforts. In this decade, vaccine effectiveness has ranged from 19% to 60%.³ However, models suggest that even when the vaccine is only 20% effective, vaccinating 140 million people (the average number of doses delivered annually in the United States over the past 5 seasons) prevents 21 million infections, 130,000 hospitalizations, and more than 61,000 deaths.⁴ In a case-control study, Flannery et al found that vaccination was 65% effective in preventing laboratory-confirmed influenza-associated death in children over 4 seasons (July 2010 through June 2014).⁵

Deciding who should be vaccinated is simpler than in prior years: Rather than targeting people who are at higher risk (those ages 65 and older, or those with comorbidities), the current CDC recommendation is to vaccinate nearly everyone ages 6 months or older, with limited exceptions.^6,7 (See Table 1⁸).

Formulations. Many types of influenza vaccine are approved for use in the United States; these differ in the number of strains included (3 or 4), the amount of antigen present for each strain, the presence of an adjuvant, the growth medium used for the virus, and the route of administration (see Table 2⁹). The relative merits of each type are a matter of some debate. There is ongoing research into the comparative efficacy of vaccines comprised of egg- vs cell-based cultures, as well as studies comparing high-dose or adjuvant vaccines to standard-dose inactivated vaccines.

Previously, the CDC has recommended preferential use (or avoidance) of some vaccine types, based on their efficacy. For the 2018-2019 flu season, however, the CDC has rescinded its recommendation against vaccine containing live attenuated virus (LAIV; FluMist brand) and expresses no preference for any vaccine formulation for patients of appropriate age and health status.¹⁰ The American Academy of Pediatrics (AAP), however, is recommends that LAIV be used only if patients and their families decline injectable vaccines.¹¹

Timing. Influenza vaccines are now distributed as early as July to some locations, raising concerns about waning immunity from early vaccination (July/August) if the influenza season does not peak until February or March.^8,12,13 Currently, the CDC recommends balancing the possible benefit of delayed vaccination against the risks of missed opportunities to vaccinate, a possible early season, and logistical problems related to vaccinating the same number of people in a smaller time interval. Offering vaccination by the end of October, if possible, is recommended in order for immunity to develop by mid-November.⁸ Note: Children ages 6 months to 8 years will need to receive their initial vaccination in 2 half-doses administered at least 28 days apart; completing their vaccination by the end of October would require starting the process weeks earlier.

Continue to: Strategy 2