Flu Vaccines for the 2024–25 Season: ACIP's Recommendations on Who, When and Which Vaccine

The Advisory Committee on Immunization Practices (ACIP) recommends annual flu vaccination for everyone aged 6 months and older who has no contraindication — as it and CDC have since 2010. This is its guidance for the 2024–25 U.S. season, updating 2023–24.

Why vaccinate

Flu usually circulates from late fall to early spring. Most people recover, but it can cause serious illness, hospitalization and death — above all in older adults, very young children, pregnant people and people with certain chronic conditions — and it keeps people out of work and school. How well the vaccine works varies with the person's age and health, the vaccine, the viruses circulating and how well they match the vaccine.

• In each season from 2010–11 to 2015–16, vaccination prevented an estimated 1.6–6.7 million illnesses, 790,000–3.1 million outpatient visits, 39,000–87,000 hospitalizations and 3,000–10,000 deaths.
• In the severe 2017–18 season it prevented about 7.1 million illnesses, 3.7 million medical visits, 109,000 hospitalizations and 8,000 deaths — though overall effectiveness was only 38%.

What changed for 2024–25

1. Every vaccine is trivalent. With no confirmed detections of wild-type B/Yamagata viruses anywhere since March 2020, the B/Yamagata component was dropped. The three components:

2. Adult solid organ transplant recipients, aged 18–64, on immunosuppressive medicines, may receive the high-dose (HD-IIV3) or adjuvanted (aIIV3) vaccine — acceptable options, not preferred over other age-appropriate vaccines. A systematic review found better antibody responses and no added risk of graft rejection, but no difference in flu hospitalization.

Otherwise ACIP prefers no vaccine over another, except for people 65 and older.

The vaccines

Injectable vaccines go into the muscle — the deltoid for adults and older children, the thigh for infants and young children. Afluria is also licensed by jet injector for ages 18–64. LAIV3 is 0.1 mL in each nostril; if the person sneezes, don't repeat it. Don't delay vaccination to get a particular product.

When

• Most people: ideally in September or October — but keep vaccinating as long as flu circulates, even in December or later. No booster is recommended.
• July and August: avoid for most adults — especially those 65+ — and for people in the first or second trimester, because protection wanes; in one meta-analysis, effectiveness against H3N2 fell from 45% in the first 3 months to 13% at 4–6 months. Early vaccination is reasonable for children who need two doses, children who need one (e.g., at a back-to-school visit), people in the third trimester (it protects the newborn), and anyone who might not get vaccinated later.

Children

Doses. Children aged 6 months through 8 years need 2 doses, at least 4 weeks apart, unless they have had at least 2 trivalent or quadrivalent doses, 4+ weeks apart, before July 1, 2024 — not necessarily in the same or consecutive seasons. The first dose should come as soon as possible, so the second is in by the end of October. A child who turns 9 between doses still gets both. Everyone 9 and older needs one dose.

Flu vaccine dosing for children aged 6 months through 8 years, 2024–25. ACIP.

Volumes for ages 6–35 months: Afluria 0.25 mL (from a multidose vial — 0.25-mL prefilled syringes are no longer available); Fluarix, Flucelvax and FluLaval 0.5 mL; Fluzone either volume. From 3 years, every IIV3 is 0.5 mL; a short dose given by mistake is made up at once, or repeated in full.

Who matters most

When supply is short, focus on those at higher risk of complications (in no order):

• children 6–59 months; everyone 50+;
• chronic lung (including asthma), heart (not isolated hypertension), kidney, liver, neurologic, blood or metabolic disorders (including diabetes);
• immunocompromise of any cause;
• pregnancy during flu season;
• ages 6 months–18 years on aspirin or salicylates (risk of Reye syndrome);
• nursing home and long-term care residents;
• American Indian or Alaska Native people;
• extreme obesity (adult BMI 40+).

And the people around them: health care personnel of every kind, paid or unpaid; household contacts and caregivers of children under 5 — above all babies under 6 months — and of adults 50+ and people with high-risk conditions.

Special situations

• Pregnancy: vaccinate in any trimester, with IIV3 or RIV3; not LAIV3 (fine postpartum). Vaccination protects the parent and the infant's first months. A larger follow-up study found no link to miscarriage.
• 65 and older: preferably HD-IIV3, RIV3 or aIIV3 — any one; none has proved consistently better than the others. If none is available, any age-appropriate vaccine.
• Immunocompromised: IIV3 or RIV3, never LAIV3. Response may be weaker; timing around treatment may matter.
• Guillain-Barré syndrome within 6 weeks of a past flu vaccine: a precaution. People not at high risk usually shouldn't be vaccinated (antiviral prophylaxis is an alternative); for high-risk people the benefit may outweigh the risk.
• Egg allergy: vaccinate, with any age-appropriate vaccine, and no extra precautions — whatever the past reaction. Reviews of egg-based flu vaccines given to egg-allergic people found no anaphylaxis.
• Severe allergy to a past flu vaccine:

A "precaution" vaccine is given in a medical setting supervised by someone who can manage severe allergic reactions; an allergist can help find the cause. Every vaccination site should be ready for anaphylaxis, and a 15-minute seated wait after any vaccine helps prevent injury from fainting.

• Travel: flu runs about October–May in the Northern Hemisphere, April–September in the Southern, and year-round in the tropics. Vaccinate at least 2 weeks before departure — especially high-risk people going to the tropics, the Southern Hemisphere in its season, or on cruises or tour groups — then get the new U.S. vaccine in the fall.
• Antivirals: fine with IIV3 and RIV3. They may blunt LAIV3: revaccinate with another vaccine if oseltamivir or zanamivir was taken from 48 hours before to 2 weeks after, peramivir from 5 days before, or baloxavir from 17 days before.
• Other vaccines: can be given the same day, at different sites — HD-IIV3 and aIIV3 in a different limb from other reactogenic vaccines. Two live vaccines not given together need 4 weeks between them.

Who should not get the nasal spray (LAIV3)

Contraindications: severe allergy to any flu vaccine or a component; children and teens on aspirin or salicylates; children 2–4 with asthma or wheezing in the past 12 months; immunocompromise (including asplenia, such as from sickle cell anemia); contacts and caregivers of severely immunosuppressed people in a protected environment; pregnancy; cerebrospinal fluid leaks or cochlear implants; recent antivirals (above).

Precautions: moderate or severe acute illness; Guillain-Barré within 6 weeks of a flu vaccine; asthma at 5 and older; other conditions that raise the risk of flu complications.

Storage and reporting

• Store vaccine at 36°F–46°F (2°C–8°C), protected from light; discard any that has frozen, or is past its expiration or beyond-use date.
• Report adverse events to VAERS — required for some, encouraged for any significant event.
• The National Vaccine Injury Compensation Program (1-800-338-2382) compensates people injured by covered vaccines, without a lawsuit.
• Surveillance: FluView; questions: CDC-INFO, 1-800-232-4636; more at cdc.gov/flu.

Sources

Based on Grohskopf LA, Ferdinands JM, Blanton LH, Broder KR, Loehr J, "Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2024–25 Influenza Season," MMWR Recommendations and Reports, volume 73, Centers for Disease Control and Prevention; a work of the United States government in the public domain. The dosing chart, which the import left as a link, was recovered from the Internet Archive's copy.