Flu Vaccine Recommendations for the 2020–21 Season: ACIP's Guidance

This page summarizes recommendations for the 2020–21 flu season, published during the COVID-19 pandemic. Vaccine composition and guidance are updated every year; check current CDC recommendations.

Flu circulates in the United States every year, mostly from late fall to early spring. Most people recover, but flu can cause serious illness, hospitalization and death, especially among older adults, very young children, pregnant women and people with certain chronic conditions, and it is a major cause of missed work and school. Since 2010, CDC and its Advisory Committee on Immunization Practices (ACIP) have recommended routine annual flu vaccination for everyone aged 6 months and older who has no contraindication, using a licensed vaccine appropriate for the person's age. ACIP expressed no preference for one product over another when more than one suitable vaccine is available.

Why vaccinate

How well the vaccine works varies with the person's age and health, the vaccine type, the circulating viruses and how well they match the vaccine. But it provides important protection. In each of the six seasons from 2010–11 through 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 respiratory and circulatory deaths. In the severe 2017–18 season, it prevented an estimated 7.1 million illnesses, 3.7 million medical visits, 109,000 hospitalizations and 8,000 deaths, even though overall effectiveness was 38%.

Flu and COVID-19. The 2020–21 season was expected to overlap with continued circulation of SARS-CoV-2. Flu vaccination would reduce flu illness, and with it symptoms that could be confused with COVID-19, and cutting flu-related outpatient visits, hospitalizations and intensive care admissions could ease strain on the health care system. For people acutely ill with suspected or confirmed COVID-19, clinicians could consider delaying flu vaccination until they recovered, reminding them to come back.

What was new for 2020–21

• Updated vaccine strains for the influenza A(H1N1)pdm09, A(H3N2) and B/Victoria components; quadrivalent vaccines also kept the unchanged B/Yamagata component. Egg-based and cell- or recombinant-based vaccines used slightly different reference viruses.
• Two new vaccines for people 65 and older: Fluzone High-Dose Quadrivalent, licensed in November 2019 to replace the trivalent high-dose vaccine, with four times the antigen of standard-dose vaccines (60 μg versus 15 μg per virus) in a 0.7 mL dose; and Fluad Quadrivalent, licensed in February 2020, containing the adjuvant MF59, alongside the existing trivalent Fluad.
• Most vaccines for the season were quadrivalent, except adjuvanted Fluad, available in trivalent and quadrivalent forms.
• Updated guidance on the live nasal vaccine, flu antivirals and egg allergy.

When to vaccinate

Vaccination was recommended by the end of October, balancing the unpredictable start of flu season against the possibility that protection wanes over a season. Vaccinating in July or August could leave people, especially older adults, less protected late in the season. In 27 of 36 seasons from 1982–83 through 2017–18 (75%), flu activity did not peak until January or later, and in 21 (58%) it peaked in February or later. Because of the pandemic, programs might need to start earlier and run longer to vaccinate everyone despite distancing measures. Vaccination should continue as long as flu viruses circulate and unexpired vaccine is available, even in December or later, and should be offered at routine visits and hospital stays. People who had already had flu that season should still be vaccinated, since the vaccine may protect against other circulating strains.

Priority groups when supply is short

Everyone 6 months and older should be vaccinated, but when vaccine is limited, priority goes to people at higher risk of complications:

• all children aged 6 through 59 months, and all people aged 50 and older
• adults and children with chronic lung (including asthma), heart (excluding isolated high blood pressure), kidney, liver, neurologic, blood or metabolic disorders (including diabetes)
• people who are immunocompromised for any reason, including medications or HIV
• women who are or will be pregnant during flu season
• children and teens (6 months to 18 years) taking aspirin or salicylates, who could develop Reye syndrome after flu
• nursing home and long-term care residents
• American Indians and Alaska Natives
• people with extreme obesity (body mass index of 40 or more in adults)

Emphasis also goes to those who live with or care for them: health care personnel, paid and unpaid; and household contacts and caregivers of young children (especially babies under 6 months), adults 50 and older, and people with high-risk conditions. Caregivers of severely immunocompromised patients needing a protected environment should receive an injectable (inactivated or recombinant) vaccine, not the live nasal one; health care workers who receive the live vaccine should avoid caring for such patients for 7 days.

Children aged 6 months through 8 years

Children in their first season of vaccination need 2 doses at least 4 weeks apart. For 2020–21, a child in this age group needed only 1 dose if they had previously received at least 2 doses of flu vaccine at least 4 weeks apart before July 1, 2020, in any seasons; otherwise, or if their history was unknown, 2 doses, even if they turned 9 between doses. Children 9 and older and adults need 1 dose.

Children aged 6 through 35 months could receive any of four licensed quadrivalent inactivated vaccines, each with its own dose volume (Afluria Quadrivalent 0.25 mL; Fluarix Quadrivalent and FluLaval Quadrivalent 0.5 mL; Fluzone Quadrivalent 0.25 or 0.5 mL, though 0.25 mL prefilled syringes were not expected that season). Healthy children aged 2 and older could instead receive the live nasal vaccine, 0.1 mL in each nostril.

Special groups

Pregnancy. Pregnant and postpartum women are at higher risk of severe flu, especially in the second and third trimesters. ACIP and the American College of Obstetricians and Gynecologists recommend vaccination for anyone who is or may be pregnant or postpartum during flu season, at any point in pregnancy, with an inactivated or recombinant vaccine, not the live vaccine. Most studies have found no link to adverse pregnancy outcomes including miscarriage; a signal in one early study was not confirmed in a larger follow-up.

Older adults. High-dose, adjuvanted and recombinant vaccines have each been studied against standard-dose vaccine in older adults. The trivalent high-dose vaccine has the most evidence, showing 24.2% better efficacy than standard dose in a two-season trial of 31,989 people aged 65 and older. Direct comparisons between the newer options were limited, so ACIP stated no preference: any age-appropriate inactivated vaccine (standard or high dose, trivalent or quadrivalent, with or without adjuvant) or the recombinant vaccine was acceptable, and vaccination should not be delayed to wait for a particular product.

Immunocompromised people should receive an inactivated or recombinant vaccine, not the live vaccine; their immune response may be weaker, and timing around treatments may matter.

Guillain-Barré syndrome. A history of GBS within 6 weeks of a previous flu shot is a precaution. People not at high risk of flu complications with such a history generally should not be vaccinated, and antiviral prophylaxis may be an alternative; for high-risk people, the benefits may outweigh the risks.

Egg allergy. Except for the recombinant (Flublok Quadrivalent, 18 and older) and cell-culture (Flucelvax Quadrivalent, 4 and older) vaccines, flu vaccines are grown in eggs and may contain trace egg protein. People who have had only hives after eating egg can receive any appropriate vaccine. Those with more serious reactions may too, but if a vaccine other than the recombinant or cell-culture vaccine is used, it should be given in a medical setting supervised by a provider who can manage severe allergic reactions. A previous severe allergic reaction to flu vaccine itself is a contraindication. Providers should consider observing anyone for 15 minutes after any vaccine in case of fainting.

Travelers at higher risk who were not vaccinated the previous fall or winter should consider vaccination at least 2 weeks before visiting the tropics, the Southern Hemisphere during its April–September flu season, or traveling with large tour groups or on cruise ships.

Flu antivirals do not interfere with inactivated or recombinant vaccines but may weaken the live vaccine. Its package insert warns against antivirals from 48 hours before to 14 days after vaccination, and the longer-lasting peramivir and baloxavir might interfere from 5 and 17 days before, respectively. People who take antivirals in these windows should be revaccinated with an injectable vaccine.

Other vaccines. Inactivated and recombinant flu vaccines can be given with other vaccines at separate sites, and the live nasal vaccine with other live or inactivated vaccines; two live vaccines not given together should be at least 4 weeks apart. In children aged 6 through 23 months, giving flu vaccine with pneumococcal conjugate or DTaP vaccine has been linked to more fever and febrile seizures on the day of and day after vaccination, but after weighing risks and benefits ACIP made no change; most febrile seizures are brief and have a good outcome. When another vaccine with a newer nonaluminum adjuvant (such as Shingrix) is given at the same time, a nonadjuvanted flu vaccine may be considered.

Sources

• Grohskopf LA, Alyanak E, Broder KR, Blanton LH, Fry AM, Jernigan DB, Atmar RL. "Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — United States, 2020–21 Influenza Season." MMWR Recommendations and Reports 69(8). https://www.cdc.gov/mmwr/volumes/69/rr/rr6908a1.htm
• CDC influenza vaccine recommendations and Background Document: https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html; CDC flu site: https://www.cdc.gov/flu
• The report's figure is not reproduced here because one of its authors is from a non-federal institution.