FDA Licenses First At-Home Administered Influenza Vaccine

• by Carolyn Hendler, JD

• Published October 7, 2024
• Vaccines

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The U.S. Food and Drug Administration (FDA) has licensed  the first of its kind live attenuated nasal spray influenza vaccine that can be administered at home. Adults up to the age 49 will be eligible to self-administer the FluMist Home vaccine or give it to their children two to 17 years old as long as they have a prescription.¹

The intranasal vaccine, FluMist, manufactured by AstraZeneca, was licensed in 2003 for people aged five through 49, but the license was modified in 2007 to include children as young as two years of age. The pharmaceutical giant has contracted with a third-party on-line pharmacy to distribute the at-home intra-nasal vaccine. Patients will undergo a screening and if they meet the criteria will receive a prescription for the vaccine which will be mailed directly to their home.²

Despite the pharmaceutical company providing data in hopes of having the vaccine available  to be administered at home for this flu season, the FDA did not license it in time so FluMist Home will not be available until next flu season.^{3 4}

Health Professionals Have Mixed Opinions About Novel Approach to Vaccination

Some health experts believe that this novel method of vaccination could increase influenza vaccination rates. Scott Roberts, MD, an infectious disease doctor at Yale School of Medicine opined:

This is the only needle-free option. Many who forego vaccination due to injection fears will be able to get vaccinated in a much easier way with self-administration”⁵

Andrew Handel, MD, a pediatric infectious disease physician, argued that Flumist may be more effective than the inactivated influenza vaccine (IAV) since it is a live virus vaccine, but he admits that not all studies agree with this conclusion.⁶

John Lowe, MD stated:

It has this advantage over the injection in that it can elicit a more physiological sort of interaction with the immune system than the injection, which simply presents the body with a dead virus for the body to form an immune response against it.⁷

Other healthcare professionals have expressed concerns that patients will fail to self-administer the vaccine properly thereby decreasing its effectiveness.⁸

FluMist Deemed Ineffective by the CDC in the Past

In 2016, the nasal vaccine briefly lost the recommendation of the U.S. Centers for Disease Control (CDC) due to evidence that it provided “poor or relatively lower effectiveness” compared to other inactivated injectible influenza vaccines. The CDC’s Advisory Committee on Immunization Practices (ACIP) had reviewed data from 2013 through 2016 and found that the FluMist Quadrivalent vaccine was merely three percent effective in preventing type A or B influenza in children.⁹

After AstraZeneca reformulated the vaccine in 2018, the live attenuated intranasal influenza vaccine was once again recommended by the CDC. However, the newer formulation has never been evaluated for effectiveness compared to other available influenza vaccines due to its limited use.¹⁰

FluMist Can Case Shedding and Transmission of Vaccine Strain Influenza Virus

Since FluMist uses a live weakened version of the influenza virus, immunocompromised individuals and pregnant women are not eligible for the new vaccine.¹¹ Live virus vaccines can shed and transmit vaccine strain virus to other people¹² There have been reports in the medical literature of cases where the FluMist caused shedding and transmission of vaccine strain influenza virus.¹³ A 2023 study in India showed that after one day of receiving a live attenuated influenza vaccine given intranasally, 71.2 percent of the recipients shed at least one of the influenza vaccine virus strains and 42.3 percent continued to shed virus on day four.¹⁴

AstraZeneca admits that the live virus intranasal vaccines have the potential to cause shedding of vaccine strain viruses on the product insert which reads:

Immune mechanisms conferring protection against influenza following receipt of FluMist Quadrivalent vaccine are not fully understood; serum antibodies, mucosal antibodies, and influenza-specific T cells may play a role. FluMist and FluMist Quadrivalent contain live attenuated influenza viruses that must infect and replicate in cells lining the nasopharynx of the recipient to induce immunity. Vaccine viruses capable of infection and replication can be cultured from nasal secretions obtained from vaccine recipients (shedding).¹⁵

An AstraZeneca representative said:

We’re working diligently to bring this ‘first-of-its-kind’ innovative and convenient self-administrated flu vaccine to consumers and look forward to launching FluMist Home as soon as next flu season.¹⁶

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