View source for Live attenuated influenza vaccine

{{Short description|Nasal influenza vaccine}}
{{See Wiktionary||laiv|redirect=laiv}}
{{Use American English|date=August 2025}}
{{Use dmy dates|date=June 2024}}
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| type = vaccine
| image = 14234CDC Flumist.tif
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| alt = refer to caption
| caption = Nurse administering the FluMist product

<!-- Vaccine data -->
| target = [[Influenza]]
| vaccine_type = attenuated

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| pronounce =
| tradename = Flumist, Flumist Quadrivalent, Fluenz Tetra
| Drugs.com = {{drugs.com|monograph|influenza-vaccine-live-intranasal}}
| MedlinePlus =
| DailyMedID = Flumist
| pregnancy_AU = <!-- A / B1 / B2 / B3 / C / D / X -->
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| routes_of_administration = [[Nasal administration|Intranasal]]
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| ATC_suffix = BB03
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| legal_US_comment = <ref name="Flumist FDA label">{{cite web | title=Flumist- influenza vaccine live intranasal spray | website=[[DailyMed]] | date=6 August 2024 | url=https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=6d9b6c87-784e-4f8a-8c82-1a7a97193337 | access-date=21 September 2024}}</ref><ref name="FDA Flumist" /><ref name="FDA Flumist Quadrivalent" />
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'''Live attenuated influenza vaccine''' ('''LAIV''') is a type of [[influenza vaccine]] in the form of a [[nasal spray]] that is recommended for the prevention of influenza.{{zwj}}<ref name="Flumist FDA label" />{{zwj}}<ref name="cite pmid|18662737">{{cite journal | vauthors = Block SL, Yogev R, Hayden FG, Ambrose CS, Zeng W, Walker RE | title = Shedding and immunogenicity of live attenuated influenza vaccine virus in subjects 5-49 years of age | journal = [[Vaccine (journal)|Vaccine]] | volume = 26 | issue = 38 | pages = 4940–4946 | date = September 2008 | pmid = 18662737 | doi = 10.1016/j.vaccine.2008.07.013 }}</ref>

It is an attenuated live vaccine, unlike other influenza vaccines, which are [[inactivated vaccine]]s. {{abbr|LAIV|live attenuated influenza vaccine}} is administered [[Nasal vaccine|intranasally]],{{zwj}}<ref name="cite pmid|17301299">{{cite journal | vauthors = Belshe RB, Edwards KM, Vesikari T, Black SV, Walker RE, Hultquist M, Kemble G, Connor EM | title = Live attenuated versus inactivated influenza vaccine in infants and young children | journal = [[The New England Journal of Medicine]] | volume = 356 | issue = 7 | pages = 685–696 | date = February 2007 | pmid = 17301299 | doi = 10.1056/NEJMoa065368 | collaboration = CAIV-T Comparative Efficacy Study Group | doi-access = free }}</ref> while inactivated vaccines are administered by [[intramuscular injection]]. {{abbr|LAIV|live attenuated influenza vaccine}} is sold under the brand names '''FluMist''' and '''FluMist Quadrivalent''' in the United States; and the brand name '''Fluenz Tetra''' in the European Union.{{zwj}}<ref name="FDA Flumist Quadrivalent">{{cite web | title=FluMist Quadrivalent | website=U.S. [[Food and Drug Administration]] (FDA) | date=15 November 2019 | url=https://www.fda.gov/vaccines-blood-biologics/vaccines/flumist-quadrivalent | id=STN 125020 | access-date=28 November 2019 | archive-date=28 November 2019 | archive-url=https://web.archive.org/web/20191128063439/https://www.fda.gov/vaccines-blood-biologics/vaccines/flumist-quadrivalent | url-status=dead }}</ref>{{zwj}}<ref name="Fluenz Tetra EPAR">{{cite web | title=Fluenz Tetra EPAR | website=[[European Medicines Agency]] (EMA) | date=17 September 2018 | url=https://www.ema.europa.eu/en/medicines/human/EPAR/fluenz-tetra | archive-url=https://web.archive.org/web/20191128060755/https://www.ema.europa.eu/en/medicines/human/EPAR/fluenz-tetra | archive-date=28 November 2019 | url-status=live | access-date=27 November 2019}}</ref> FluMist was first introduced in{{nbsp}}2003 by [[MedImmune]].{{zwj}}<ref name="FDA Statement">{{cite web | title=FDA Information Regarding FluMist Quadrivalent Vaccine | website=U.S. [[Food and Drug Administration]] (FDA) | date=16 January 2018 | url=https://www.fda.gov/vaccines-blood-biologics/vaccines/fda-information-regarding-flumist-quadrivalent-vaccine | archive-url=https://web.archive.org/web/20191128063252/https://www.fda.gov/vaccines-blood-biologics/vaccines/fda-information-regarding-flumist-quadrivalent-vaccine | archive-date=28 November 2019 | url-status=dead | access-date=27 November 2019}}</ref>{{zwj}}<ref name="approval">{{cite web|url=https://www.fda.gov/cber/approvltr/inflmed061703L.htm |title=CBER Approval Letter, Influenza Virus Vaccine, Live, Intranasal (FluMist) | vauthors = Midthun K, Masiello S |date=17 July 2003 |publisher=[[U.S. Food and Drug Administration]] (FDA) |access-date=6 July 2008 |archive-url=https://web.archive.org/web/20070929154324/https://www.fda.gov/cber/approvltr/inflmed061703L.htm |archive-date=29 September 2007 |url-status=dead }}</ref><ref name="FluMist FDA archive">{{cite web | title=FluMist | website=U.S. [[Food and Drug Administration]] (FDA) | url=https://www.fda.gov/BiologicsBloodVaccines/Vaccines/ApprovedProducts/ucm094047.htm | url-status=dead | archive-date=22 July 2017 | archive-url=https://wayback.archive-it.org/7993/20170722071650/https://www.fda.gov/BiologicsBloodVaccines/Vaccines/ApprovedProducts/ucm094047.htm | access-date=10 April 2020 }}</ref>

In the United States, FluMist is approved for self- or caregiver-administration.{{zwj}}<ref name="FDA PR 20240920">{{cite web | title=FDA Approves Nasal Spray Influenza Vaccine for Self- or Caregiver-Administration | website=U.S. Food and Drug Administration | date=20 September 2024 | url=https://www.fda.gov/news-events/press-announcements/fda-approves-nasal-spray-influenza-vaccine-self-or-caregiver-administration | archive-url=https://web.archive.org/web/20240920160515/https://www.fda.gov/news-events/press-announcements/fda-approves-nasal-spray-influenza-vaccine-self-or-caregiver-administration | url-status=dead | archive-date=20 September 2024 | access-date=21 September 2024}} {{PD-notice}}</ref>{{zwj}}<ref>{{cite news | last=Jewett | first=Christina | title=Nasal Flu Vaccine Is Approved for At-Home Use | newspaper=The New York Times | date=20 September 2024 | url=https://www.nytimes.com/2024/09/20/health/nasal-flu-vaccine-approved.html | access-date=24 September 2024}}</ref> It is the first influenza{{nbsp}}vaccine that does not need to be administered by a health care provider.{{zwj}}<ref name="FDA PR 20240920" />

==Medical uses==
The live attenuated influenza vaccine is used to provide protection against [[the flu]], caused by infection with influenza viruses.{{zwj}}<ref>{{cite web | title=Live Intranasal Influenza Vaccine Information Statement | website=[[Centers for Disease Control and Prevention]] (CDC) | url=https://www.cdc.gov/vaccines/hcp/vis/vis-statements/flulive.html | date=August 2021 | access-date=22 June 2022 | archive-date=31 July 2020 | archive-url=https://web.archive.org/web/20200731163847/https://www.cdc.gov/vaccines/hcp/vis/vis-statements/flulive.html | url-status=live }}</ref>{{zwj}}<ref>{{cite web | title=Live Attenuated Influenza Vaccine. The Nasal Spray Flu Vaccine | website=[[Centers for Disease Control and Prevention]] (CDC) | date=15 October 2021 | url=https://www.cdc.gov/flu/prevent/nasalspray.htm | access-date=22 June 2022 | archive-date=14 October 2019 | archive-url=https://web.archive.org/web/20191014221155/https://www.cdc.gov/flu/prevent/nasalspray.htm | url-status=live }}</ref>{{zwj}}<ref name="FDA Flumist">{{cite web | title=FluMist | website=U.S. [[Food and Drug Administration]] (FDA) | date=17 April 2019 | url=https://www.fda.gov/vaccines-blood-biologics/vaccines/flumist | id=STN: 125020 | access-date=22 June 2022 | archive-date=23 June 2022 | archive-url=https://web.archive.org/web/20220623042238/https://www.fda.gov/vaccines-blood-biologics/vaccines/flumist | url-status=dead }}</ref>

==Contraindications==
The use of the live attenuated influenza vaccine is [[contraindicated]], and it should therefore not be used, in the following populations:
* Children under{{nbsp}}{{Val|24|u=months of age}}, due to increased risk of wheezing{{zwj}}<ref name="Flumist Canadian Product Monograph">{{cite book|last=[[AstraZeneca Inc.]]|title=Product Monograph: FluMist|year=2013|publisher=self-published|via=[[Health Canada]]|url=http://webprod5.hc-sc.gc.ca/dpd-bdpp/item-iteme.do?pm-mp=00021215|access-date=27 August 2013|archive-url=https://web.archive.org/web/20140723153629/http://webprod5.hc-sc.gc.ca/dpd-bdpp/item-iteme.do?pm-mp=00021215|archive-date=23 July 2014|url-status=dead}}</ref>
* Individuals with a history of hypersensitivity to previous influenza vaccination{{zwj}}<ref name="Flumist Canadian Product Monograph" />
* Individuals with a history of hypersensitivity, especially [[anaphylactic reactions]], to eggs, egg proteins, [[gentamicin]], [[gelatin]], or [[arginine]] or to any other ingredient in the formulation{{zwj}}<ref name="Flumist Canadian Product Monograph" />
* People with a medical condition that places them at high risk for complications from influenza, including those with [[Chronic heart disease|chronic heart]] or [[Chronic lung disease (disambiguation)|lung disease]], such as [[asthma]] or [[reactive airways disease]]{{zwj}}<ref name="QandA">{{cite web|url=https://www.cdc.gov/flu/about/qa/nasalspray.htm|title=The Nasal-Spray Flu Vaccine (Live Attenuated Influenza Vaccine <nowiki>[LAIV]</nowiki>)|date=22 January 2008|publisher=US [[National Center for Immunization and Respiratory Diseases]]|access-date=6 July 2008|url-status=dead|archive-url=https://web.archive.org/web/20091126010356/http://cdc.gov/flu/about/qa/nasalspray.htm|archive-date=26 November 2009}}</ref>
* People with medical conditions such as [[diabetes]] or [[kidney failure]] or people with illnesses that [[Immunodeficiency|weaken the immune system]], or who take medications that can weaken the immune system{{zwj}}<ref name="QandA" />
* Children less than{{nbsp}}{{Val|5|u=years old}} with a history of recurrent wheezing{{zwj}}<ref name="QandA" />
* Children or adolescents receiving [[aspirin]]{{zwj}}<ref name="QandA" />
* People with a history of [[Guillain–Barré syndrome|{{langr|fr|Guillain–Barré|cat=no}} syndrome]], a rare disorder of the nervous system{{zwj}}<ref name="QandA" />
* Pregnant women{{zwj}}<ref name="QandA" />
* People who have a severe allergy to chicken eggs or who are allergic to any of the nasal spray vaccine components{{zwj}}<ref name="QandA" />

==Production==
The live attenuated vaccine is based on a [[flu strain]] that does not cause disease, that replicates well at relatively cold temperatures (about {{Convert|25|°C}}, for incubation purposes), and replicates poorly at [[Human body temperature|body temperature]] (which minimizes risk to humans). Genes that code for [[surface proteins]] (targeted [[antigen]]s) are combined with this host using [[genetic reassortment]] from strains that [[Influenza vaccine reformulation|are projected to be circulating widely]] in the coming months. The resulting viruses are then incubated in chicken eggs and chick kidney cells. To make the refrigerated version, the virus is purified in [[centrifuge]]s through a [[sucrose]]{{nbsp}}gradient, then packaged with sucrose, [[phosphate]], [[glutamate]], [[arginine]], and [[hydrolyzed]] pig [[gelatin]].{{zwj}}<ref>{{cite web |archive-url=https://web.archive.org/web/20180126151132/https://www.fda.gov/ohrms/dockets/ac/07/briefing/2007-4292B1-02.pdf |archive-date=26 January 2018 |title=FluMist Live, Attenuated Influenza Vaccine Briefing Document |author=FDA Vaccines and Related Biological Products Advisory Committee |website=[[Food and Drug Administration]] |date=April 2007 |url=https://www.fda.gov/ohrms/dockets/ac/07/briefing/2007-4292B1-02.pdf}}</ref>

==Risks==
Even though the virus in the live attenuated influenza vaccine{{nbsp}}(LAIV) is [[Attenuated vaccine|attenuated]] (low in [[virulence]]), it is still a living virus, and may cause an [[infection]] with complications in people with [[weakened immune systems]] or other underlying medical conditions. {{abbr|LAIV|live attenuated influenza vaccine}} is recommended only for people {{Val|2|–|49|u=years of age}}, and people who have a weakened immune system, pregnant women, and people with certain chronic diseases may not be eligible to receive the vaccine.{{zwj}}<ref>{{cite web |title=Facts and Myths about FluMist |url=https://www.flumistquadrivalent.com/flu-vaccine-resources/flu-vaccine-myths-vs-facts.html |author=AstraZeneca |publisher=self-published |access-date=10 November 2020 |date=September 2020 |archive-date=11 November 2020 |archive-url=https://web.archive.org/web/20201111025038/https://www.flumistquadrivalent.com/flu-vaccine-resources/flu-vaccine-myths-vs-facts.html |url-status=live }}</ref> In contrast, [[Inactivated influenza vaccine|inactivated virus vaccines]] contain no living virus, and cannot cause a live{{nbsp}}infection. Persons receiving {{abbr|LAIV|live attenuated influenza vaccine}} may shed small amounts of the vaccine virus during the first week. People coming in contact with the vaccinated person are not considered to be at risk, unless their immune systems are severely weakened (for example, [[bone marrow transplant]] recipients).{{zwj}}<ref name="cite pmid|18662737" />

==History==
The live attenuated influenza vaccine{{nbsp}}(LAIV) was developed by the [[University of Michigan School of Public Health]] in [[Ann Arbor, Michigan]] and later by [[Aviron]], in [[Mountain View, California]], under the sponsorship of the [[National Institutes of Health]]{{nbsp}}(NIH) in the{{nbsp}}1990s. [[MedImmune]] purchased Aviron in 2002, and the US{{nbsp}}[[Food and Drug Administration]]{{nbsp}}(FDA) approved {{abbr|LAIV|live attenuated influenza vaccine}} in June{{nbsp}}2003.{{zwj}}<ref>{{cite news|url=https://www.usatoday.com/news/health/2004-01-07-flumist_x.htm|title=Nasal FluMist overcomes obstacles to reach public| vauthors = Appleby J |date=7 January 2004|work=[[USA Today]]|access-date=6 July 2008|archive-date=22 May 2006|archive-url=https://web.archive.org/web/20060522073634/http://www.usatoday.com/news/health/2004-01-07-flumist_x.htm|url-status=live}}</ref>{{zwj}}<ref name="FluMist FDA archive" />

The FDA initially approved {{abbr|LAIV|live attenuated influenza vaccine}} only for healthy people aged 5{{nbsp}}to 49 because of concerns over possible side effects. {{abbr|LAIV|live attenuated influenza vaccine}} is approved and recommended for healthy{{nbsp}}children {{Val|24|u=months of age}} and{{nbsp}}older. The{{nbsp}}FDA approved the unfrozen refrigerated{{nbsp}}version for the same age group (ages 5–49) in August{{nbsp}}2006, following completion of [[Phase III clinical trials|phase{{nbsp}}III clinical trials]].{{zwj}}<ref name="Drug Week">{{cite news|url=http://www.newsrx.com/newsletters/Lab-Law-Weekly/2006-08-25/08212006333927LL.html|title=MedImmune begins shipping live intranasal flu vaccine for 2006-2007 after U.S. FDA release|date=25 August 2006|work=Lab Law Weekly|access-date=6 July 2008|archive-date=14 July 2011|archive-url=https://web.archive.org/web/20110714175206/http://www.newsrx.com/newsletters/Lab-Law-Weekly/2006-08-25/08212006333927LL.html|url-status=live}}</ref>

The cold-adapted version of the vaccine is called CAIV-T, and is stable for storage in a refrigerator, rather than requiring freezer storage as did the originally-approved formulation. Approved for the 2007-2008 flu{{nbsp}}season,{{zwj}}<ref name="FluMist FDA archive" /> the refrigerated formulation can be distributed more cheaply, making it more price-competitive with injected vaccines. The higher price hampered sales of the original frozen version of FluMist; FluMist was initially priced higher than injectable vaccines, and sold only 500,000 of the four{{nbsp}}million doses produced its first year on the market, despite a comparative shortage of flu{{nbsp}}vaccine in fall{{nbsp}}2004.{{zwj}}<ref>{{cite news|url=https://www.washingtonpost.com/ac2/wp-dyn/A51955-2005Jan5|title=FluMist Sales Falling Short, Survey Finds| vauthors = Rosenwald M |date=6 January 2005|newspaper=[[The Washington Post]]|page=E05|access-date=6 July 2008}}{{dead link|date=June 2021|bot=medic}}{{cbignore|bot=medic}}</ref> The price was sharply lowered the next year, and MedImmune reported distributing 1.6{{nbsp}}million doses in{{nbsp}}2005.{{zwj}}<ref>{{cite news|url=http://www.newsrx.com/issue_article/Pharma-Business-Week/2006-02-27/02272006333154PB.html|title=MedImmune reports revenues of $1.2 billion|date=27 February 2006|work=Pharma Business Week|access-date=6 July 2008|archive-date=5 January 2009|archive-url=https://web.archive.org/web/20090105223411/http://www.newsrx.com/issue_article/Pharma-Business-Week/2006-02-27/02272006333154PB.html|url-status=live}}</ref> Because of the price drop, despite selling almost three{{nbsp}}times as many doses in{{nbsp}}2005, the company reported $21{{nbsp}}million in revenue from FluMist sales,{{zwj}}{{NoteTag|1=equivalent to ${{Format price|{{Inflation|US-GDP|21000000|2005|r=-6}}}} in {{Inflation/year|US-GDP}}{{zwj}}{{Inflation/fn|US-GDP}}}} compared to $48{{nbsp}}million the previous year.{{zwj}}<ref>{{cite news|url=https://www.washingtonpost.com/wp-dyn/content/article/2006/02/02/AR2006020202320.html|title=Sales of MedImmune's Flu Vaccine Drop Sharply| vauthors = Rosenwald M |date=3 February 2006|newspaper=[[The Washington Post]]|page=D04|access-date=6 July 2008|archive-date=23 October 2016|archive-url=https://web.archive.org/web/20161023045918/http://www.washingtonpost.com/wp-dyn/content/article/2006/02/02/AR2006020202320.html|url-status=live}}</ref>{{zwj}}{{NoteTag|1=equivalent to ${{Format price|{{Inflation|US-GDP|48000000|2004|r=-6}}}} in {{Inflation/year|US-GDP}}{{zwj}}<ref name="inflation-USGDP" />}}

==Society and culture==
[[File:Flumist Home Vaccine Kit.jpg|thumb|An example of a Flumist home influenza vaccine kit, featuring unpacking and administration instructions, safety warnings, and the box containing the vaccine itself. The kit is shipped in a styrofoam cooler with [[Ice pack|cold packs]] to maintain the vaccine at a refrigerated temperature (not shown).]]
[[MedImmune]] is one company that manufactures the live attenuated influenza vaccine, which it sells under the brand name FluMist in the United States, Canada, and Japan,{{zwj}}<ref>{{Cite news |last=Cameron |first=Isabel |date=17 July 2023 |title=FluMist Quadrivalent 'unlikely' to see great success in Japan |url=https://www.biopharma-reporter.com/Article/2023/07/17/flumist-quadrivalent-unlikely-to-see-great-success-in-japan |access-date=6 May 2024 |website=Biopharma Reporter |publisher=[[William Reed Business Media]] |archive-url=https://web.archive.org/web/20230929163420/https://www.biopharma-reporter.com/Article/2023/07/17/flumist-quadrivalent-unlikely-to-see-great-success-in-japan |archive-date=29 September 2023 |url-status=dead |language=en-GB}}</ref> and the brand name Fluenz Tetra in the UK and European Union.{{zwj}}<ref name="Fluenz Tetra EPAR" /> For the 2010–2011 flu{{nbsp}}season, FluMist was the only live attenuated influenza vaccine approved by the{{nbsp}}FDA for use in the{{nbsp}}US.{{zwj}}<ref>{{cite web |title=2010-2011 Influenza Season Vaccine Questions and Answers |website=U.S. [[Food and Drug Administration]] (FDA) |url= https://www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Post-MarketActivities/LotReleases/ucm220649.htm |url-status=dead |archive-date=4 April 2017 |archive-url=https://wayback.archive-it.org/7993/20170404210758/https://www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Post-MarketActivities/LotReleases/ucm220649.htm | access-date=9 April 2020}}</ref>{{zwj}}<ref>{{cite web |title=Influenza Virus Vaccine for the 2010-2011 Season |website=U.S. [[Food and Drug Administration]] (FDA) |url=https://www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Post-MarketActivities/LotReleases/ucm202750.htm | url-status=dead |archive-date=6 April 2017 |archive-url=https://wayback.archive-it.org/7993/20170406072657/https://www.fda.gov/BiologicsBloodVaccines/GuidanceComplianceRegulatoryInformation/Post-MarketActivities/LotReleases/ucm202750.htm | access-date=9 April 2020}}</ref> All other FDA-approved lots were inactivated virus vaccines.{{zwj}}{{citation needed|date=April 2020}} In September{{nbsp}}2009, a live attenuated influenza vaccine for [[2009 H1N1 influenza pandemic|the novel H1N1 influenza virus]] was approved{{zwj}}<ref name="CDC-AH1N1" /> and the seasonal intranasal vaccine was approved by the [[European Medicines Agency]]{{nbsp}}(EMA) for use in the European Union in 2011.{{zwj}}<ref name="Fluenz EPAR">{{cite web | title=Fluenz EPAR | website=[[European Medicines Agency]] (EMA) | date=17 September 2018 | url=https://www.ema.europa.eu/en/medicines/human/EPAR/fluenz | access-date=9 April 2020 | archive-date=31 July 2020 | archive-url=https://web.archive.org/web/20200731182306/https://www.ema.europa.eu/en/medicines/human/EPAR/fluenz | url-status=live }}</ref> The [[wikt:quadrivalent|quadrivalent]] vaccine version was approved for use in the European Union in{{nbsp}}2013.{{zwj}}<ref name="Fluenz Tetra EPAR" />

{{As of|2007}},{{Update inline|date=August 2025}} the only other company holding live attenuated influenza vaccine rights is [[BioDiem]] of{{nbsp}}Australia.{{zwj}}<ref>{{cite web|url=http://www.biotechnologynews.net/storyview.asp?StoryID=97712|title=MedImmune takeover holds promise for BioDiem|date=26 April 2007|website=BioTechnologyNews|access-date=21 October 2013|archive-date=21 October 2013|archive-url=https://web.archive.org/web/20131021191754/http://www.biotechnologynews.net/storyview.asp?StoryID=97712|url-status=live}}</ref> BioDiem licensed rights to private production of the vaccine in China to [[Changchun BCHT Biotechnology]], which also holds public rights for production in China sublicensed from the [[World Health Organization]].{{zwj}}<ref>{{cite web|url=http://www.researchinchina.com/Htmls/News/201202/30360.html|title=BioDiem licenses LAIV technology to Changchun BCHT|publisher=ResearchInChina|date=10 February 2012|access-date=21 October 2013|archive-date=21 October 2013|archive-url=https://web.archive.org/web/20131021201044/http://www.researchinchina.com/Htmls/News/201202/30360.html|url-status=live}}</ref>

It was the first and, {{as of|2007|lc=yes}}, the only live attenuated vaccine for influenza available outside of Europe.{{zwj}}<ref>{{cite journal | vauthors = Harper SA, Fukuda K, Cox NJ, Bridges CB | title = Using live, attenuated influenza vaccine for prevention and control of influenza: supplemental recommendations of the Advisory Committee on Immunization Practices (ACIP) | journal = [[MMWR Recommendations and Reports]] | volume = 52 | issue = RR-13 | pages = 1–8 | date = September 2003 | pmid = 14557799 | url = https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5213a1.htm | access-date = 9 September 2017 | url-status = live | archive-url = https://web.archive.org/web/20171123222650/https://www.cdc.gov/mmwr/preview/mmwrhtml/rr5213a1.htm | archive-date = 23 November 2017 }}</ref> In September{{nbsp}}2009, a live attenuated influenza vaccine for the novel{{nbsp}}H1N1 influenza virus was approved.{{zwj}}<ref name="CDC-AH1N1">{{cite web | url=http://www.cdc.gov/mmwr/pdf/wk/mm5839.pdf | title=Update on Influenza A (H1N1) 2009 Monovalent Vaccines | date=9 October 2009 | access-date=23 October 2009 | archive-date=6 April 2020 | archive-url=https://web.archive.org/web/20200406133526/https://www.cdc.gov/mmwr/preview/mmwrhtml/mm5839a3.htm | url-status=live }}</ref> In 2011, the vaccine was approved by the [[European Medicines Agency]]{{nbsp}}(EMA) for use in the European Union under the brand name Fluenz.{{zwj}}<ref name="Fluenz EPAR" />{{zwj}}<ref>{{cite press release | title=European Commission approves nasal spray vaccine Fluenz for the prevention of seasonal influenza in children | author=AstraZeneca | website=AstraZeneca Media Centre | date=1 February 2011 | url=https://www.astrazeneca.com/media-centre/press-releases/2011/AstraZeneca-approves-nasal-spray-vaccine-Fluenz-for-flu-01022011.html | access-date=29 August 2022 | archive-date=13 June 2022 | archive-url=https://web.archive.org/web/20220613011355/https://www.astrazeneca.com/media-centre/press-releases/2011/AstraZeneca-approves-nasal-spray-vaccine-Fluenz-for-flu-01022011.html | url-status=live }}</ref>

[[AstraZeneca]] acquired MedImmune in{{nbsp}}2007 and retired the MedImmune name.{{zwj}}<ref>{{cite press release | title=AstraZeneca Ships FluMist Quadrivalent Vaccine in the US for 2020-2021 Flu Season | author=[[AstraZeneca]] | via=[[Business Wire]] | date=13 August 2020 | url=https://www.businesswire.com/news/home/20200813005173/en/AstraZeneca-Ships-FLUMIST%C2%AE-QUADRIVALENT-Vaccine-2020-2021-Flu | access-date=8 July 2021 | archive-date=9 July 2021 | archive-url=https://web.archive.org/web/20210709185710/https://www.businesswire.com/news/home/20200813005173/en/AstraZeneca-Ships-FLUMIST%C2%AE-QUADRIVALENT-Vaccine-2020-2021-Flu | url-status=live }}</ref>{{zwj}}<ref>{{cite web | title=AstraZeneca retires Medimmune name amid sales turnaround | website=[[BioPharma Dive]] | date=14 February 2019 | url=https://www.biopharmadive.com/news/astrazeneca-retires-medimmune-name-amid-sales-turnaround/548489/ | access-date=8 July 2021 | archive-date=9 July 2021 | archive-url=https://web.archive.org/web/20210709190304/https://www.biopharmadive.com/news/astrazeneca-retires-medimmune-name-amid-sales-turnaround/548489/ | url-status=live }}</ref> In October{{nbsp}}2024, [[Time (magazine)|''Time'' magazine]] named AstraZeneca{{nbsp}}FluMist (an "at-home nasal vaccine") as one of the best inventions of{{nbsp}}2024.{{zwj}}<ref>{{Cite magazine |last=Park |first=Alice |date=2024-10-30 |title=AstraZeneca FluMist: the 200 Best Inventions of 2024 |url=https://time.com/7094894/astrazeneca-flumist/ |access-date=2024-11-02 |magazine=[[Time (magazine)|Time]] |language=en}}</ref>

=== Legal status ===
In May{{nbsp}}2024, the [[Committee for Medicinal Products for Human Use]]{{nbsp}}(CHMP) of the [[European Medicines Agency]]{{nbsp}}(EMA) adopted a positive opinion, recommending the granting of a marketing authorization for Fluenz, intended for the prevention of influenza disease in children and adolescents.{{zwj}}<ref name="Fluenz EPAR 2" />{{zwj}}<ref>{{cite press release | title=Meeting highlights from the Committee for Medicinal Products for Human Use (CHMP) 27-30 May 2024 | website=European Medicines Agency | date=31 May 2024 | url=https://www.ema.europa.eu/en/news/meeting-highlights-committee-medicinal-products-human-use-chmp-27-30-may-2024 | access-date=13 June 2024}}</ref> The applicant for this medicinal product is AstraZeneca{{nbsp}}AB.{{zwj}}<ref name="Fluenz EPAR 2">{{cite web | title=Fluenz EPAR | website=European Medicines Agency | date=21 May 2024 | url=https://www.ema.europa.eu/en/medicines/human/EPAR/fluenz-0 | access-date=1 June 2024}}</ref>

In September 2024, the US{{nbsp}}FDA approved FluMist for self- or caregiver-administration. The{{nbsp}}FDA granted the approval of FluMist to MedImmune{{nbsp}}LLC.{{zwj}}<ref name="FDA PR 20240920" />

==Research==
{{Update|section|date=August 2025}}
The live attenuated influenza vaccine is designed to be quickly modifiable to present the surface antigens of seasonal flu. This modifiability could also allow it to be quickly customized as a vaccine against a [[pandemic influenza]] if one were to emerge. In light of the [[global spread of H5N1]], ways of reducing [[Human mortality from H5N1|human mortality in the event of an H5N1 pandemic]] have been investigated. Modifying FluMist to serve as a specific human H5N1 vaccine is among the measures studied.{{zwj}}<ref>{{cite journal | vauthors = Luke CJ, Subbarao K | title = Vaccines for pandemic influenza | journal = [[Emerging Infectious Diseases]] | volume = 12 | issue = 1 | pages = 66–72 | date = January 2006 | pmid = 16494720 | pmc = 3291408 | doi = 10.3201/eid1201.051147 | url = https://wwwnc.cdc.gov/eid/article/12/1/pdfs/05-1147.pdf | access-date = 23 June 2022 | url-status = live | archive-url = https://web.archive.org/web/20220204034931/https://wwwnc.cdc.gov/eid/article/12/1/pdfs/05-1147.pdf | archive-date = 4 February 2022 }}</ref>

In June{{nbsp}}2006, the US{{nbsp}}[[National Institutes of Health]]{{nbsp}}(NIH) began enrolling participants in a [[H5N1 clinical trials|Phase I H5N1 study]] of an intranasal [[influenza vaccine]] candidate based on [[MedImmune]]'s live, attenuated vaccine technology.{{zwj}}<ref>{{cite press release | title=MedImmune and National Institutes of Health Begin Clinical Testing of a Live, Attenuated Intranasal Vaccine Against an H5N1 Avian Influenza Virus | website=phx.corporate-ir.net | date=15 June 2006 | url=http://phx.corporate-ir.net/phoenix.zhtml?c=83037&p=irol-newsArticle_Print&ID=872852&highlight= | archive-url=https://web.archive.org/web/20160109053654/http://phx.corporate-ir.net/phoenix.zhtml?c=83037&p=irol-newsArticle_Print&ID=872852&highlight= | archive-date=9 January 2016 | url-status=dead | access-date=22 June 2022}}</ref>

In September{{nbsp}}2006, the US{{nbsp}}[[National Institute of Allergy and Infectious Diseases]]{{nbsp}}(NIAID) reported that inoculation with a live attenuated influenza vaccine modified to present surface antigens of certain H5N1 variants provided broad protection against other H5N1 variants in [[Animal model|mouse and ferret models]].{{zwj}}<ref>{{cite journal | vauthors = Suguitan AL, McAuliffe J, Mills KL, Jin H, Duke G, Lu B, Luke CJ, Murphy B, Swayne DE, Kemble G, Subbarao K | title = Live, attenuated influenza A H5N1 candidate vaccines provide broad cross-protection in mice and ferrets | journal = [[PLOS Medicine]] | volume = 3 | issue = 9 | pages = e360 | date = September 2006 | pmid = 16968127 | pmc = 1564176 | doi = 10.1371/journal.pmed.0030360 | doi-access = free }} {{open access}}</ref> Attenuated live viruses were found protective against H5N1 in mice and chickens in a 2009{{nbsp}}study.{{zwj}}<ref>{{cite journal | vauthors = Steel J, Lowen AC, Pena L, Angel M, Solórzano A, Albrecht R, Perez DR, García-Sastre A, Palese P | title = Live attenuated influenza viruses containing NS1 truncations as vaccine candidates against H5N1 highly pathogenic avian influenza | journal = [[Journal of Virology]] | volume = 83 | issue = 4 | pages = 1742–1753 | date = February 2009 | pmid = 19073731 | pmc = 2643794 | doi = 10.1128/JVI.01920-08 }}</ref>

"Several trials have reported that live attenuated influenza vaccines can boost virus-specific CTLs as well as mucosal and serum antibodies and provide broad cross-protection against heterologous human influenza A viruses." (58, 59){{zwj}}<ref name="ReferenceA">{{cite journal | vauthors = Lee LY, Ha D, Simmons C, de Jong MD, Chau NV, Schumacher R, Peng YC, McMichael AJ, Farrar JJ, Smith GL, Townsend AR, Askonas BA, Rowland-Jones S, Dong T | title = Memory T cells established by seasonal human influenza A infection cross-react with avian influenza A (H5N1) in healthy individuals | journal = [[The Journal of Clinical Investigation]] | volume = 118 | issue = 10 | pages = 3478–3490 | date = October 2008 | pmid = 18802496 | pmc = 2542885 | doi = 10.1172/JCI32460 }}</ref> "[V]accine formulas inducing [[heterosubtypic]] T cell–mediated immunity may confer broad protection against avian and human influenza A viruses."{{zwj}}<ref name="ReferenceA" />

== Notes ==
{{NoteFoot}}

== References ==
{{Reflist}}

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[[Category:2009 swine flu pandemic]]
[[Category:Drugs developed by AstraZeneca]]
[[Category:Influenza vaccines]]
[[Category:Live vaccines]]