CDC director Tom Frieden receives his annual flu shot. Courtesy of the CDC
While current U.S. flu activity is low overall, localized influenza outbreaks have been reported. Influenza activity often begins to increase in October. The Centers for Disease Control and Prevention (CDC) recommends a yearly flu vaccine for everyone 6 months and older. Now is a good time to get vaccinated. It takes about two weeks after vaccination for protection to set in.
Flu vaccination can reduce flu illnesses and prevent flu-related hospitalizations. Flu vaccines have been updated for the 2016-2017 season. More than 90 million doses of seasonal influenza vaccine have been distributed at this time.
Influenza viruses typically circulate widely in the United States annually, from the late fall through early spring. Although most persons who become infected with influenza viruses will recover without sequelae, influenza can cause serious illness and death, particularly among older adults, very young children, pregnant women, and those with chronic medical conditions. During 31 seasons from the 1976-77 through the 2006-07 season, estimated influenza-associated deaths ranged from approximately 3,300 to 49,000 annually. Annual influenza vaccination is the primary means of preventing influenza and its complications. A variety of different types of influenza vaccine are available. Abbreviation conventions for the different types of vaccine have evolved over time. Routine annual influenza vaccination for all persons aged ≥6 months who do not have contraindications has been recommended by CDC and CDC’s Advisory Committee on Immunization Practices (ACIP) since 2010.
ACIP provides annual recommendations for the prevention and control of influenza. The ACIP Influenza Work Group meets by teleconference once to twice per month throughout the year. Work Group membership includes several voting members of ACIP and representatives of ACIP Liaison Organizations* Discussions include topics such as influenza surveillance, vaccine effectiveness and safety, vaccine coverage, program feasibility, cost-effectiveness, and vaccine supply. Presentations are requested from invited experts, and published and unpublished data are discussed.
For unchanged recommendations, literature published since release of the last ACIP influenza Recommendations and Reports in MMWR (September, 2013) was reviewed. Updates to the recommendations described in in this document are of three types: 1) the vaccine viruses included in the 2016–17 seasonal influenza vaccines, 2) new vaccine licensures and approvals, and 3) an interim recommendation that live attenuated influenza vaccine (LAIV4) not be used during the 2016–17 season.
Recommendations for vaccine viruses to be included in Northern Hemisphere influenza vaccines are made by the World Health Organization (WHO), which organizes a consultation, generally in February of each year, to make recommendations for vaccine composition. Surveillance data are reviewed and candidate vaccine viruses are discussed. A summary of the WHO meeting for selection of the 2016–17 Northern Hemisphere vaccine viruses is available at http://www.who.int/influenza/vaccines/virus/recommendations/201602_recommendation.pdf?ua=1. Subsequently, the Food and Drug Administration (FDA), which has regulatory authority over vaccines in the United States, convenes a meeting of its Vaccines and Related Biologic Products Advisory Committee (VRBPAC), which considers the recommendations of WHO, reviews and discusses similar data, and makes a final decision regarding vaccine virus composition for influenza vaccines licensed and marketed in the United States. A summary of the FDA VRBPAC meeting of March 4, 2016, at which composition of the 2016–17 U.S. influenza vaccines was discussed, is available at http://www.fda.gov/downloads/AdvisoryCommittees/CommitteesMeetingMaterials/BloodVaccinesandOtherBiologics/VaccinesandRelatedBiologicalProductsAdvisoryCommittee/UCM494071.pdf.
With regard to recommendations for newly licensed influenza vaccines and changes to the licensed indications for existing vaccines, ACIP relies on FDA, which has regulatory authority for review of safety, immunogenicity, and effectiveness data and licensure of influenza vaccines. Regulatory information pertinent to the two recently licensed products discussed in this report may be found at http://www.fda.gov/BiologicsBloodVaccines/SafetyAvailability/VaccineSafety/ucm473989.htm (for Fluad; Seqirus, Holly Springs, NC) and at http://www.fda.gov/BiologicsBloodVaccines/Vaccines/ApprovedProducts/ucm502844.htm (for Flucelvax; Seqirus, Holly Springs, NC).
For interim changes in the recommendation for use of LAIV4, in June 2016, ACIP reviewed newly available data concerning the effectiveness of LAIV4 for the 2015–16 season. The information reviewed comes from three unpublished observational studies. Presentations of preliminary data reviewed by the ACIP may be found at http://www.cdc.gov/vaccines/acip/meetings/meetings-info.html. Minutes of the June ACIP meeting may be found at http://www.cdc.gov/vaccines/acip/meetings/minutes-archive.html. ACIP will review subsequent data as they become available.
Information presented in this report reflects recommendations presented during ACIP public meetings and approved on October 21, 2015; February 24, 2016; and June 22, 2016. Meeting minutes and information on ACIP membership and conflicts of interest are available on the ACIP website (http://www.cdc.gov/vaccines/acip). Modifications were made to the ACIP recommendations during subsequent review at CDC to update and clarify wording in the document. Further updates, if needed, will be posted at CDC’s influenza website (http://www.cdc.gov/flu).
Primary Changes and Updates in the Recommendations
Routine annual influenza vaccination of all persons aged ≥6 months without contraindications continues to be recommended. No preferential recommendation is made for one influenza vaccine product over another for persons for whom more than one licensed, recommended product is otherwise appropriate. Updated information and guidance in this document includes the following:
•In light of low effectiveness against influenza A(H1N1)pdm09 in the United States during the 2013–14 and 2015–16 seasons, for the 2016–17 season, ACIP makes the interim recommendation that LAIV4 should not be used. Because LAIV4 is still a licensed vaccine that might be available and that some providers might elect to use, for informational purposes, reference is made to previous recommendations for its use.
•2016–17 U.S. trivalent influenza vaccines will contain an A/California/7/2009 (H1N1)–like virus, an A/Hong Kong/4801/2014 (H3N2)–like virus and a B/Brisbane/60/2008–like virus (Victoria lineage). Quadrivalent vaccines will include an additional vaccine virus strain, a B/Phuket/3073/2013–like virus (Yamagata lineage).
•Recent new vaccine licensures are discussed:
An MF59-adjuvanted trivalent inactivated influenza vaccine (aIIV3), Fluad (Seqirus, Holly Springs, North Carolina), was licensed by FDA in November 2015 for persons aged ≥65 years. Regulatory information is available at http://www.fda.gov/BiologicsBloodVaccines/SafetyAvailability/VaccineSafety/ucm473989.htm. aIIV3 is an acceptable alternative to other vaccines licensed for persons in this age group. ACIP and CDC do not express a preference for any particular vaccine product.
A quadrivalent formulation of Flucelvax (cell culture-based inactivated influenza vaccine [ccIIV4], Seqirus, Holly Springs, North Carolina) was licensed by FDA in May 2016, for persons aged ≥4 years. Regulatory information is available at: http://www.fda.gov/BiologicsBloodVaccines/Vaccines/ApprovedProducts/ucm502844.htm. ccIIV4 is an acceptable alternative to other vaccines licensed for persons in this age group. No preference is expressed for any particular vaccine product.
•Recommendations for influenza vaccination of persons with egg allergy have been modified, including
Removal of the recommendation that egg-allergic recipients should be observed for 30 minutes post-vaccination for signs and symptoms of an allergic reaction. Providers should consider observing all patients for 15 minutes after vaccination to decrease the risk for injury should they experience syncope, per the ACIP General Recommendations on Immunization.
A recommendation that persons with a history of severe allergic reaction to egg (i.e., any symptom other than hives) should be vaccinated in an inpatient or outpatient medical setting (including but not necessarily limited to hospitals, clinics, health departments, and physician offices), under the supervision of a health care provider who is able to recognize and manage severe allergic conditions.