Influenza viruses typically circulate in the United States annually, most commonly from late fall through early spring. Most persons who contract influenza will recover without sequelae. However, influenza can cause serious illness, hospitalization, and death, particularly among older adults, very young children, pregnant women, and those with certain chronic medical conditions.

A person receives the seasonal influenza vaccine (flu shot). Imahe/NIAID
A person receives the seasonal influenza vaccine (flu shot).
Imahe/NIAID

Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications.

On Friday, officials with the Centers for Disease Control and Prevention (CDC) published in the MMWR —Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices—United States, 2018–19 Influenza Season.

The vaccine for the 2018–19 Influenza Season

Vaccine viruses included in the 2018–19 U.S. trivalent influenza vaccines will be an A/Michigan/45/2015 (H1N1)pdm09–like virus, an A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus, and a B/Colorado/06/2017–like virus (Victoria lineage).

Quadrivalent influenza vaccines will contain these three viruses and an additional influenza B vaccine virus, a B/Phuket/3073/2013–like virus (Yamagata lineage).

In addition, recommendations for the use of LAIV4 (FluMist Quadrivalent) have been updated. Following two seasons (2016–17 and 2017–18) during which Advisory Committee on Immunization Practices (ACIP) recommended that LAIV4 not be used, for the 2018–19 season, vaccination providers may choose to administer any licensed, age-appropriate influenza vaccine (IIV, RIV4, or LAIV4). LAIV4 is an option for those for whom it is appropriate.

Recommendations and guidance

The authors of MMWR paper say balancing considerations regarding the unpredictability of timing of onset of the influenza season and concerns that vaccine-induced immunity might wane over the course of a season, it is recommended that vaccination should be offered by the end of October.

Children aged 6 months through 8 years who require 2 doses (see Children Aged 6 Months Through 8 Years) should receive their first dose as soon as possible after vaccine becomes available, to allow the second dose (which must be administered ≥4 weeks later) to be received by the end of October.

Optimally, vaccination should occur before onset of influenza activity in the community.

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Populations at Higher Risk for Medical Complications Attributable to Severe Influenza

All persons aged ≥6 months without contraindications should be vaccinated annually. However, vaccination to prevent influenza is particularly important for persons who are at increased risk for severe complications from influenza and for influenza-related outpatient, emergency department, or hospital visits. When vaccine supply is limited, vaccination efforts should focus on delivering vaccination to persons at higher risk for medical complications attributable to severe influenza who do not have contraindications. These persons include (no hierarchy is implied by order of listing):

  • All children aged 6 through 59 months;
  • All persons aged ≥50 years;
  • Adults and children who have chronic pulmonary (including asthma) or cardiovascular (excluding isolated hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders (including diabetes mellitus);
  • Persons who are immunocompromised due to any cause (including immunosuppression caused by medications or by HIV infection);
  • Women who are or will be pregnant during the influenza season;
  • Children and adolescents (aged 6 months through 18 years) who are receiving aspirin- or salicylate-containing medications and who might be at risk for experiencing Reye syndrome after influenza virus infection;
  • Residents of nursing homes and other long-term care facilities;
  • American Indians/Alaska Natives; and
  • Persons who are extremely obese (body mass index ≥40).

Read more at MMWR

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