As the 2020-21 flu season looms in the midst of the ongoing Covid-19 pandemic, the CDC’s Advisory Committee on Immunization Practices (ACIP) released updates to its recommendations for using seasonal influenza vaccines.
The annual flu season has a major impact on the U.S. each year. According to CDC estimates, during the most recent flu season from Oct.1, 2019 through April 4, 2020, there were between 39,000,000-56,000,000 cases of the flu, 18,000,000-26,000,000 flu-related medical visits, 410,000-740,000 flu-related hospitalizations, and between 24,000-62,000 flu-related deaths — and this year, the U.S. has to contend with the ongoing Covid-19 pandemic, which can present with symptoms similar to the flu and is set to place an additional strain on the nation’s healthcare infrastructure.
In its new recommendations, which were published in Morbidity and Mortality Weekly Report, Lisa A. Grohskopf, MD, of the Influenza Division at the National Center for Immunization and Respiratory Disease, CDC, and colleagues outlined the composition of this year’s flu vaccines. “For the 2020–21 season, U.S. egg-based influenza vaccines (i.e., vaccines other than ccIIV4 and RIV4) will contain hemagglutinin (HA) derived from an influenza A/Guangdong-Maonan/SWL1536/2019 (H1N1)pdm09-like virus, an influenza A/Hong Kong/2671/2019 (H3N2)-like virus, an influenza B/Washington/02/2019 (Victoria lineage)-like virus, and (for quadrivalent egg-based vaccines) an influenza B/Phuket/3073/2013 (Yamagata lineage)-like virus,” they wrote. “U.S. cell culture–based inactivated (ccIIV4) and recombinant (RIV4) influenza vaccines will contain HA derived from an influenza A/Hawaii/70/2019 (H1N1)pdm09-like virus, an influenza A/Hong Kong/45/2019 (H3N2)-like virus, an influenza B/Washington/02/2019 (Victoria lineage)-like virus, and an influenza B/Phuket/3073/2013 (Yamagata lineage)-like virus.”
New Vaccines, New Contraindications
Notably, ACIP pointed out two new flu vaccines that will be available this flu season. The first, Fluzone High-Dose Quadrivalent (HD-IIV4), gained FDA approval in November 2019 and is expected to replace the trivalent formulation of Fluzone High-Dose that was available in previous years — HD-IIV4 contains 4 times the amount of HA per vaccine virus in each dose compared with standard-dose inactivated influenza vaccines (60μg per virus vs. 15μg in standard-dose IIVs), ACIP noted. The second new vaccine, Fluad Quadrivalent (aIIV4), was FDA-approved in February 2020 and, like it’s trivalent predecessor, contains the adjuvant MF59. Both the quadrivalent and the trivalent formulation of Fluad are expected to be available for the 2020-21 flu season. Both of these vaccines, ACIP noted, are indicated for patients ≥65 years of age.
Other changes to ACIP’s influenza vaccine recommendations include the addition of new contraindications for patients receiving a quadrivalent live attenuated influenza vaccine (LAIV4). As of this update, LAIV4 vaccines should not be given to patients with anatomic and functional asplenia; patients with active communication between the cerebrospinal fluid (CSF) and oropharynx, nasopharynx, nose, or ear or any other cranial CSF leak; and patients with cochlear implant, due to the potential for CSF leak. Also, ACIP’s recommendations for persons with a history of egg allergy were updated to state that “additional measures for those with a history of severe allergic reaction to egg (i.e., vaccination in a medical setting supervised by a health care provider who is able to recognize and manage severe allergic reactions) are needed only if a vaccine other than [quadrivalent cell culture-based inactivated influenza vaccine] ccIIV4 or [quadrivalent recombinant influenza vaccine] RIV4 is used.”
Who Should Get Vaccinated, and When
As in previous years, ACIP recommended that all persons 6 months and older who do not have contraindications receive a flu vaccine. When vaccine supply is limited, vaccination efforts should focus on delivering vaccination to the following high-risk populations:
- Children age 6 through 59 months.
- People age ≥50 years.
- “Adults and children who have chronic pulmonary (including asthma), cardiovascular (excluding isolated hypertension), renal, hepatic, neurologic, hematologic, or metabolic disorders (including diabetes mellitus).
- “Persons who are immunocompromised due to any cause (including but not limited to immunosuppression caused by medications or 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.
- “Persons who are extremely obese (body mass index ≥40 for adults).”
As for when individuals should get vaccinated, ACIP suggested offering vaccines to patients by the end of October. Children ages 6 months through 8 years who need to receive two vaccine doses “should receive their first dose as soon as possible after the vaccine becomes available to allow the second dose (which must be administered ≥4 weeks later) to be received by the end of October,” ACIP wrote. “For those requiring only 1 dose for the season, early vaccination (i.e., in July and August) is likely to be associated with suboptimal immunity before the end of the influenza season, particularly among older adults. Community vaccination programs should balance maximizing the likelihood of persistence of vaccine-induced protection through the season with avoiding missed opportunities to vaccinate or vaccinating after onset of influenza circulation occurs.”
The Covid-19 pandemic, however, may complicate things. It is currently anticipated that SARS-CoV-2 and influenza virus will be active at the same time in the U.S. during the upcoming flu season — to account for this, flu vaccination programs might need to work around stay-at-home orders and social distancing measures by starting vaccination campaigns sooner.
Covid-19 and Flu Vaccination
ACIP noted that Covid-19 infections might place a substantial burden on the nation’s healthcare infrastructure this flu season without proper precautions. “The extent to which SARS-CoV-2 will circulate over the course of the 2020–21 influenza season is unknown,” ACIP wrote. “However, during the continued or recurrent circulation of SARS-CoV-2 concurrently with influenza viruses during the upcoming fall and winter, influenza vaccination of persons aged ≥6 months can reduce prevalence of illness caused by influenza, and can also reduce symptoms that might be confused with those of COVID-19.”
As for patients who have suspected or confirmed Covid-19 infection, ACIP noted that clinical experience with flu vaccination of persons with Covid-19 is extremely limited. Therefore, physicians should consider delaying influenza vaccination until these patients are no longer acutely ill, and patients should be reminded to return and receive a flu vaccine once they are recovered.
ACIP’s flu vaccine recommnedations for 2020-21 were updated to outline the composition of this year’s vaccines, as well as two newly licensed influenza vaccines—Fluzone High-Dose Quadrivalent and Fluad Quadrivalent—for patients ≥65 years old.
Other highlights of ACIP’s updated recommendations include new contraindications for patients receiving a LAIV4 vaccine; vaccine considerations for patients with a history of egg allergy; and considerations for administering flu vaccinations during the Covid-19 pandemic.
John McKenna, Associate Editor, BreakingMED™
No potential conflicts of interest were disclosed.
Cat ID: 561
Topic ID: 86,561,730,31,44,561,151,925