Seasonal Influenza Vaccines: ACIP Recommendations for the 2018–19 Season

This page describes ACIP's recommendations for the 2018–19 influenza season. Recommendations are updated every year; check current CDC guidance.

Each year the Advisory Committee on Immunization Practices (ACIP) updates its advice on how influenza vaccines should be used in the United States. The 2018–19 report replaced the 2017–18 recommendations and drew on ACIP's public meetings of October 25, 2017, February 21, 2018, and June 20, 2018.

The core recommendation

Everyone aged 6 months or older who has no contraindication should be vaccinated against influenza every year, using a licensed, recommended vaccine that is appropriate for their age. For 2018–19, providers could choose any such vaccine: an inactivated influenza vaccine (IIV), the recombinant influenza vaccine (RIV4), or the live attenuated influenza vaccine (LAIV4). ACIP expressed no preference among them, and vaccination should not be delayed to obtain a particular product.

What changed from the previous season

• The vaccine viruses. The H3N2 and B/Victoria components were changed in both trivalent and quadrivalent vaccines.
• The nasal spray vaccine returned. After two seasons (2016–17 and 2017–18) in which ACIP recommended that LAIV4 not be used, it voted in February 2018 to make LAIV4 an option again for people for whom it is appropriate.
• Egg allergy. People with egg allergy of any severity may receive any licensed, recommended, age-appropriate vaccine, now including LAIV4.
• Two age expansions. In August 2017 the Food and Drug Administration (FDA) extended Afluria Quadrivalent from people aged 18 years and older to those aged 5 years and older. In January 2018 it extended Fluarix Quadrivalent from people aged 3 years and older to those aged 6 months and older, at a 0.5 mL dose for all ages.

The 2018–19 vaccine viruses

Trivalent vaccines contained:

• 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 vaccines contained the same three plus a B/Phuket/3073/2013–like virus (Yamagata lineage).

Why the nasal spray vaccine came back

In February 2018 ACIP reviewed three sources of evidence. A pooled analysis of five U.S. observational studies (2013–14 through 2015–16) and a systematic review of U.S. and other studies (2010–11 through 2016–17) found that LAIV had worked poorly against H1N1pdm09-like viruses in children aged 2 through 17 years. It had been significantly less effective than IIV against those viruses, but it was effective against influenza B, and the two did not generally differ significantly against H3N2. No effectiveness estimates yet existed for the current formulation, which carried a new H1N1pdm09-like virus, A/Slovenia/2903/2015. The third source was manufacturer data on shedding and immune response in young children. It suggested that the new virus replicated better than the earlier H1N1pdm09-like viruses used in LAIV.

When to vaccinate

The best time to start cannot be predicted: local outbreaks can begin as early as October, but in 75% of seasons from 1982–83 through 2017–18 the peak came in January or later, and in 58% it came in February or later.

Protection may also fade within a season. An analysis from the U.S. Influenza Vaccine Effectiveness Network found effectiveness fell by about 7% a month against H3N2 and influenza B, and by 6%–11% a month against H1N1pdm09, while staying above zero for at least 5 to 6 months. A European analysis found effectiveness against H3N2 reached 0% at 111 days after vaccination.

Weighing both, ACIP recommended that vaccination be offered by the end of October. Vaccinating very early (for example, in July or August) might leave people, older adults especially, with weaker protection late in the season. Vaccination should nonetheless continue for as long as influenza viruses circulate, since activity in some communities may not start until February or March. Revaccinating someone who is already fully vaccinated later in the same season was not recommended.

Who to prioritize when vaccine is short

Everyone should be vaccinated, but when supply is limited, efforts should go first to people at higher risk of severe complications:

• all children aged 6 through 59 months, and all people aged 50 years or older;
• people with chronic lung (including asthma), heart (other than high blood pressure alone), kidney, liver, neurologic, blood or metabolic disorders, including diabetes;
• people who are immunocompromised for any reason, including medication or HIV infection;
• women who are or will be pregnant during the season;
• children and teenagers aged 6 months through 18 years taking aspirin or salicylate medicines, who might develop Reye syndrome after influenza;
• residents of nursing homes and other long-term care facilities;
• American Indians and Alaska Natives; and
• people with a body mass index of 40 or more.

Efforts should also reach health care personnel, household contacts and caregivers of children younger than 5 years and adults aged 50 or older (particularly of infants under 6 months), and household contacts and caregivers of people with high-risk conditions. Those caring for severely immunocompromised people who require a protected environment should receive IIV or RIV4 rather than LAIV4.

Children aged 6 months through 8 years

Children in this age group need two doses, at least 4 weeks apart, in their first season of vaccination. A child who received two or more doses of trivalent or quadrivalent vaccine before July 1, 2018 — not necessarily in the same or consecutive seasons — needs one dose. Otherwise, or if no one knows, the child needs two, and the first should be given as soon as vaccine is available.

CDC figure from the report.

For children aged 6 through 35 months, three quadrivalent inactivated vaccines were licensed: 0.5 mL of FluLaval Quadrivalent or Fluarix Quadrivalent (15 µg of HA per virus), or 0.25 mL of Fluzone Quadrivalent (7.5 µg of HA per virus). Healthy children aged 2 years or older could instead receive LAIV4, 0.1 mL in each nostril. Anyone aged 36 months or older receiving an IIV should get 0.5 mL per dose.

Pregnancy

Pregnant and postpartum women have been observed to be at higher risk of severe influenza, particularly in the second and third trimesters. ACIP recommended vaccination for all women who are or might be pregnant during the season, at any point in pregnancy, with an IIV or RIV4; LAIV4 should not be used in pregnancy.

Older adults

For people aged 65 or older, any age-appropriate IIV — standard-dose or high-dose, trivalent or quadrivalent, with or without adjuvant — or RIV4 was acceptable, with no preference. In a two-season randomized trial among 31,989 people aged 65 or older, Fluzone High-Dose showed a relative efficacy of 24.2% over standard-dose trivalent vaccine. In a single-season trial among 8,604 adults aged 50 or older, Flublok Quadrivalent showed a relative effectiveness of 30% over standard-dose quadrivalent vaccine, though no claim of superiority was approved for its label. In a small observational study, the adjuvanted Fluad was more effective than unadjuvanted vaccine.

Special situations

• Immunocompromised people should not receive LAIV4, and in some situations their immune response to live or inactivated vaccines might be blunted.
• Guillain-Barré syndrome within 6 weeks of an earlier influenza vaccination is a precaution. People who are not at higher risk of complications and had that reaction generally should not be vaccinated.
• Egg allergy. People who had only hives after eating egg may receive any appropriate vaccine. Those with more serious reactions may too, but in a medical setting supervised by a provider able to manage severe allergic reactions. A previous severe allergic reaction to an influenza vaccine itself is a contraindication. RIV4 (Flublok Quadrivalent) is the only vaccine considered egg-free.
• Travelers, especially higher-risk people unvaccinated the previous fall or winter, should consider vaccination at least 2 weeks before visiting the tropics, joining organized tour groups or cruises, or traveling to the Southern Hemisphere during its season (April–September).
• Antiviral medicines taken from 48 hours before to 14 days after LAIV4 may reduce its effectiveness; IIV and RIV4 are unaffected.
• Other vaccines may be given at the same visit, at separate sites. After LAIV4, at least 4 weeks should pass before another live vaccine.

Storage, reporting and compensation

Influenza vaccines are generally stored refrigerated at 2° to 8°C (36° to 46°F), protected from light, and discarded if frozen. Health care providers are required to report certain adverse events after vaccination to the Vaccine Adverse Event Reporting System (VAERS). The National Vaccine Injury Compensation Program can compensate people injured by a covered vaccine; claims must generally be filed within 3 years of the first symptom, and death claims within 2 years of the death.

Sources

• Lisa A. Grohskopf, Leslie Z. Sokolow, Karen R. Broder, Emmanuel B. Walter, Alicia M. Fry and Daniel B. Jernigan, "Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices—United States, 2018–19 Influenza Season," Morbidity and Mortality Weekly Report: Recommendations and Reports, CDC: https://www.cdc.gov/mmwr/volumes/67/rr/rr6703a1.htm
• The dosing figure is from the report.