Data ICTV MSL41 & NCBI · 9 November 2026 Methods · Changelog · Corrections

Open Source Medicine Foundation

Influenza B virus

Taxonomy pass, October 2026

ICTV species Betainfluenzavirus influenzae, family Orthomyxoviridae. What it is, and what exists against it.

At a glance

AbbreviationFLUBV
ICTV speciesBetainfluenzavirus influenzae
FamilyOrthomyxoviridae
Baltimore classV — (−)ssRNA
Human infectionHuman infection recorded; pattern not classified

Also called: Betainfluenzavirus influenzae

Riboviria › Negarnaviricota › Insthoviricetes › Articulavirales › Orthomyxoviridae › Betainfluenzavirus

What it is

Taxonomy copied from ICTV MSL41.v1 / VMR_MSL41.v1.20260729.xlsx. These ranks are not hand-edited; a correction means re-running the fetch against a newer release.

RealmRiboviria
KingdomOrthornavirae
PhylumNegarnaviricota
ClassInsthoviricetes
OrderArticulavirales
FamilyOrthomyxoviridae
GenusBetainfluenzavirus
ICTV identifierICTV19710224
NCBI taxon2955465
Exemplar isolateRNA1: M14880; RNA2: AF101982; RNA3: AF102017; RNA4: K00423; RNA5: K01395; RNA6: J02095; RNA7: J02094; RNA8: J02096
GenomeSegmented, 8 segments

Host evidence

Counts of nucleotide records annotated with that host. Evidence of provenance, not a statement of host range.

Where it occurs

Not searched yet. No country-level occurrence data has been curated for this virus. The WHO reported-case data on this site covers a limited set of diseases; a virus outside it gets no map rather than an empty one.

What it does

37
disease-burden figures
9
post-infectious sequelae figures
105
effectiveness estimates
13
randomised trial
42
pooled or expert review
50
controlled observational
Deaths per year 2018
15 300 annual number of in-hospital deaths (uncertainty range)
children under 5 years, global per hospitalised case
quote
FINDINGS: In 2018, among children under 5 years globally, there were an estimated 109·5 million influenza virus episodes (uncertainty range [UR] 63·1-190·6), 10·1 million influenza-virus-associated ALRI cases (6·8-15·1); 870 000 influenza-virus-associated ALRI hospital admissions (543 000-1 415 000), 15 300 in-hospital deaths (5800-43 800), and up to 34 800 (13 200-97 200) overall influenza-virus-associated ALRI deaths.
Wang X 2020 Lancet Glob Health
Case-fatality April 2009 to January 2010
2.9 confirmed-case CFR (%)
all ages (weighted mean age of confirmed cases 18.1 years), multiple per case
quote
The confirmed case fatality ratio was 2·9% (95% CI 0·0-6·7%), an extracted average from 12 of 42 studies reporting fatal cases (937 fatal cases among 31,980 confirmed cases), which gives an overall estimated infected case fatality ratio of 0·02%.
Khandaker G 2011 Influenza Other Respir Viruses
Incidence 2010-2016
0.15 average annual incidence per 100,000 children
children younger than 18 years, United States per population
quote
The average annual incidence was 0.15 per 100 000 children (95% confidence interval: 0.14-0.16) and was highest among children aged <6 months (incidence: 0.66; 95% confidence interval: 0.53-0.82), followed by children aged 6-23 months (incidence: 0.33; 95% confidence interval: 0.27-0.39).
Shang M 2018 Pediatrics

Lowest and highest vaccine effectiveness reported: -74% (Kissling E 2019 Euro Surveill; Medically attended laboratory-confirmed influenza A(H3N2) clade 3C.3a in 15-64-year-olds, 15-64 years) to 85.6% (Nunes MC 2016 JAMA Pediatr; PCR-confirmed influenza illness in infants aged 8 weeks or younger, infants 8 weeks of age or younger). Two of 71 estimates, each from its own study; not a summary figure.

Vaccine effectiveness against medically attended illness 41
-100%-75%-50%-25%0%25%50%75%100%

What can follow the illness

First-ever acute myocardial infarction or stroke after influenza infection
3.5 incidence rate ratio, risk period vs baseline, calendar-month adjusted
median 75 years (IQR 66-82), Denmark; vs baseline periods in the same individuals
quote
After calendar-month adjustment, the IRR for cardiovascular events during the risk period was 3.5 (95% CI: 2.6-4.7), higher for AMI (IRR = 4.7; 95% CI: 3.1-7.4) than stroke (IRR = 2.9; 95% CI: 2.0-4.2).
Croci R 2026 Euro Surveill
First-ever acute myocardial infarction after influenza infection
4.7 incidence rate ratio, risk period vs baseline
median 75 years, Denmark; vs baseline periods in the same individuals
quote
After calendar-month adjustment, the IRR for cardiovascular events during the risk period was 3.5 (95% CI: 2.6-4.7), higher for AMI (IRR = 4.7; 95% CI: 3.1-7.4) than stroke (IRR = 2.9; 95% CI: 2.0-4.2).
Croci R 2026 Euro Surveill
First-ever stroke after influenza infection
2.9 incidence rate ratio, risk period vs baseline
median 75 years, Denmark; vs baseline periods in the same individuals
quote
After calendar-month adjustment, the IRR for cardiovascular events during the risk period was 3.5 (95% CI: 2.6-4.7), higher for AMI (IRR = 4.7; 95% CI: 3.1-7.4) than stroke (IRR = 2.9; 95% CI: 2.0-4.2).
Croci R 2026 Euro Surveill

When problems appear: after the infection, and after the vaccine

Two separate clocks on the same logarithmic scale. The first starts at the infection and shows when its sequelae are described as beginning; the second starts at the dose and shows when the vaccine's adverse events are described as beginning. Each bar is one source's printed window, not a synthesis; hover for the source.

After the infection: post-infectious syndromes 6
  • Clinical description: when it is observed to begin
  • Study risk window: when events were counted, not typical onset
10 min1 h6 h1 d1 wk1 mo3 moAcute myocardial infarctionfirst 7 daysAtherothrombotic events (acute myocardi…14 daysFirst strokeremained elevated to 28 daysGuillain-Barré syndromeFirst myocardial infarctiondays 1-3Influenza-associated acute encephalopat…1.7 days
After vaccination: adverse events 7
  • Clinical description: when it is observed to begin
  • Compensation-table interval
  • Study risk window: when events were counted, not typical onset
10 min1 h6 h1 d1 wk1 mo3 moVasovagal syncope≤1 hourAnaphylaxis≤4 hoursFebrile seizures0-1 daysShoulder Injury Related to Vaccine Admi…≤48 hoursGuillain-Barré syndromeNonspecific systemic symptoms (fever, c…within 6 to 12 hoursGuillain-Barré Syndrome3-42 days

Disease risk and vaccine efficacy: every estimate with its population, design and the sentence it came from.

Each figure is the one its source printed, with the sentence it came from. Nothing is recomputed, averaged or converted.

Burden

MeasureAs the source states itSource
Annual Deaths290 000 to 650 000 respiratory deaths annuallyglobal
quote
It causes 290 000 to 650 000 respiratory deaths annually.

Influenza (seasonal) fact sheet · source · verified 2026-10-30

More, with study designs and vaccine efficacy: disease-risk page.

Vaccines

In use against this virus
NameDeveloperPlatformUseStageJurisdictionsTrialsSource
Influenza A (H5N1) Monovalent Vaccine, AdjuvantedSee FDA listingNot searched yetRoutine immunisationApprovedUS: approved—candidateId fda-influenza-a-h5n1-monovalent-vaccine-adjuvanted (target
Influenza VaccineSee FDA listingNot searched yetRoutine immunisationApprovedUS: approved—candidateId fda-influenza-vaccine (targetDisease 'Influenza'); stage c
Influenza Vaccine (Quadrivalent)See FDA listingNot searched yetRoutine immunisationApprovedUS: approved—candidateId fda-influenza-vaccine-quadrivalent (targetDisease 'Influen
Influenza Vaccine (Trivalent)See FDA listingNot searched yetRoutine immunisationApprovedUS: approved—candidateId fda-influenza-vaccine-trivalent (targetDisease 'Influenza'
Influenza Vaccine, AdjuvantedSee FDA listingNot searched yetRoutine immunisationApprovedUS: approved—candidateId fda-influenza-vaccine-adjuvanted (targetDisease 'Influenza
Influenza Virus Vaccine (Trivalent, Types A and B)See FDA listingNot searched yetRoutine immunisationApprovedUS: approved—candidateId fda-influenza-virus-vaccine-trivalent-types-a-and-b (targe
MFLUSIVA Influenza Vaccine, mRNAModernaTX, Inc. 325 Binney Street Cambridge, MA 02142 Lic. # 2256Not searched yetRoutine immunisationApprovedUS: approved—candidateId fda-mflusiva-influenza-vaccine-mrna (targetDisease 'Influe

In development

Candidates
NameDeveloperPlatformUseStageJurisdictionsTrialsSource
mRNA-1010ModernamrnaRoutine immunisationFiled with a regulatorUS: submitted (company estimate)
EU: submitted (company estimate)
Canada: submitted (company estimate)
Australia: submitted (company estimate)
—candidateId mrna-1010 (targetDisease 'Seasonal influenza'); stage copi
mRNA-1083 (Moderna Combined Influenza + COVID-19 mRNA Vaccine)ModernamrnaRoutine immunisationFiled with a regulatorUS: under review
EU: under review (company estimate)
Canada: not submitted (company estimate)
Australia: not submitted (company estimate)
—candidateId mrna-1083 (targetDisease 'Seasonal influenza + COVID-19 (c
Anflu®Sinovac Biotech Co., Ltdinactivated wholeRoutine immunisationPhase 3Not searched yetNCT07832201candidateId ctgov-anflu-sinovac-biotech-co-ltd (targetDisease 'Influen
Comparator 1GlaxoSmithKlineNot searched yetRoutine immunisationPhase 3Not searched yetNCT07851246candidateId ctgov-mrna-seasonal-flu-vaccine-glaxosmithkline (targetDis
COVID-Influenza Combination (CIC) — NovavaxNovavaxNot searched yetRoutine immunisationPhase 3Not searched yet—candidateId novavax-flu-covid (targetDisease 'Seasonal influenza + COV
FluMistWashington University School of MedicineNot searched yetRoutine immunisationPhase 3Not searched yetNCT07177417candidateId ctgov-flumist-washington-university-school-of-medicine (ta
H5N1 vaccine (Arepanrix, GSK)University Health Network, TorontoNot searched yetRoutine immunisationPhase 3Not searched yetNCT07240558candidateId ctgov-h5n1-vaccine-arepanrix-gsk-university-health-network
Influenza + COVID combination candidates (Pfizer/BioNTech family)Pfizer / BioNTechmrnaRoutine immunisationPhase 3Not searched yet—candidateId pfizer-dual-flu-covid (targetDisease 'Seasonal influenza +
Influenza vaccinationWroclaw Medical UniversityNot searched yetRoutine immunisationPhase 3Not searched yetNCT06725927 NCT07617376candidateId ctgov-influenza-vaccination-wroclaw-medical-university (ta
LAIV nasal vaccine is chosen as a model viral infectionUniversity of North Carolina, Chapel HillNot searched yetRoutine immunisationPhase 3Not searched yetNCT06841913candidateId ctgov-laiv-nasal-vaccine-is-chosen-as-a-model-viral-infect
mRNA-1018-H5ModernaTX, Inc.mrnaRoutine immunisationPhase 3Not searched yetNCT07496450candidateId ctgov-mrna-1018-h5-modernatx-inc (targetDisease 'Influenza
Seasonal influenza vaccineUniversity of PennsylvaniaNot searched yetRoutine immunisationPhase 3Not searched yetNCT05108818candidateId ctgov-seasonal-influenza-vaccine-university-of-pennsylvani
Sinovac QIV (Influenza Vaccine, Split Virion, Inactivated, Quadrivalent)Sinovac Biotech Co., Ltdinactivated wholeRoutine immunisationPhase 3Not searched yetNCT07211152candidateId ctgov-participants-will-receive-one-dose-of-vaccine-0-5-ml
Vaxigrip Tetra Sanofi Pasteur EuropeAarhus University HospitalNot searched yetRoutine immunisationPhase 3Not searched yetNCT05585983candidateId ctgov-vaxigrip-tetra-sanofi-pasteur-europe-aarhus-universi
AZD4117AstraZenecaNot searched yetRoutine immunisationPhase 2Not searched yetNCT07128615candidateId ctgov-azd4117-astrazeneca (targetDisease 'Influenza'); sta
Flu H5 egg pandemic low dose vaccine, with adjuvantSanofiNot searched yetRoutine immunisationPhase 2Not searched yetNCT07779408candidateId ctgov-flu-h5-egg-pandemic-low-dose-vaccine-with-adjuvant-s
Flu mRNA(Formulation A)GlaxoSmithKlinemrnaRoutine immunisationPhase 2Not searched yetNCT07204964candidateId ctgov-flu-mrna-formulation-b1-glaxosmithkline (targetDisea
HEXASIILSerum Institute of India Pvt. Ltd.Not searched yetRoutine immunisationPhase 2Not searched yetNCT07855172candidateId ctgov-hexavalent-dtwp-hepb-rpv-hib-vaccine-serum-institute
Pandemic flu H5 HA mRNA SD2 vaccineSanofimrnaRoutine immunisationPhase 2Not searched yetNCT06907511candidateId ctgov-pandemic-flu-h5-ha-mrna-sd2-vaccine-sanofi (targetDi
Pfizer mRNA influenza vaccine candidates (#1-#6, unnamed)PfizermrnaRoutine immunisationPhase 2Not searched yetNCT07431853candidateId ctgov-vaccine-candidate-1-pfizer (targetDisease 'Influenza
Egg-based Trivalent Split Influenza Virus Vaccine (eTIV)Sinovac Biotech Co., Ltdinactivated wholeRoutine immunisationPhase 1Not searched yetNCT07889193candidateId ctgov-cell-based-trivalent-split-influenza-virus-vaccine-c
H5 Flu IMP 2SanofiNot searched yetRoutine immunisationPhase 1Not searched yetNCT07516418candidateId ctgov-h5-flu-investigational-medical-product-imp-1-sanofi
Haemophilus Influenzae Type b Conjugate VaccineCanSino Biologics Inc.Not searched yetRoutine immunisationPhase 1Not searched yetNCT06621654candidateId ctgov-lyophilized-haemophilus-influenzae-type-b-conjugate-
Diphtheria, tetanus, pertussis, hepatitis B, Hib vaccineGlaxoSmithKlineNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT00316680candidateId ctgov-diphtheria-tetanus-pertussis-hepatitis-b-hib-vaccine
GSK Bio's influenza vaccine GSK2584786A, different formulationsGlaxoSmithKlineNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT01195779candidateId ctgov-gsk-bio-s-influenza-vaccine-gsk2584786a-different-fo
GSK Biologicals' investigational H1N1 Influenza Vaccine - GSK2340274AGlaxoSmithKlineNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT01008956candidateId ctgov-gsk-biologicals-investigational-h1n1-influenza-vacci
GSK influenza virus H5N1 vaccine 1557484AGlaxoSmithKlineNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT01045564candidateId ctgov-gsk-influenza-virus-h5n1-vaccine-1557484a-glaxosmith
GSK pandemic vaccine GSK2340272AGlaxoSmithKlineNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT01014091candidateId ctgov-gsk-pandemic-vaccine-gsk2340272a-glaxosmithkline (ta
GSK's candidate influenza vaccine 1562902AGlaxoSmithKlineNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT00866580candidateId ctgov-gsk-s-candidate-influenza-vaccine-1562902a-glaxosmit
GSK2202083A vaccineGlaxoSmithKlineNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT00871741candidateId ctgov-gsk2202083a-vaccine-glaxosmithkline (targetDisease '
GSK2231395AGlaxoSmithKlineNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT00849069candidateId ctgov-gsk2231395a-glaxosmithkline (targetDisease 'Influenz
GSK2340272A GSK Biologicals' investigational influenza pandemic vaccineGlaxoSmithKlineNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT01003418candidateId ctgov-gsk2340272a-gsk-biologicals-investigational-influenz
Infanrix-IPV/HibGlaxoSmithKlineNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT03128489candidateId ctgov-infanrix-ipv-hib-glaxosmithkline (targetDisease 'Inf
influenza surface antigen inactivated vaccineNovartisinactivated wholeRoutine immunisationDiscontinuedNot searched yetNCT00342940candidateId ctgov-influenza-surface-antigen-inactivated-vaccine-novart
Investigational H7N9 vaccine GSK3277510AGlaxoSmithKlineNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT02177734candidateId ctgov-investigational-h7n9-vaccine-gsk3277510a-glaxosmithk
NanoFlu (Quad-NIV, Matrix-M)NovavaxNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT03658629candidateId ctgov-nanoflu-quad-niv-novavax (targetDisease 'Influenza')
PandemrixTMGlaxoSmithKlineNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT01160237candidateId ctgov-pandemrixtm-glaxosmithkline (targetDisease 'Influenz
Quadrivalent Influenza Vaccine (split virion, inactivated) High-Dose (QIV-HD)Sanofi Pasteur, a Sanofi Companyinactivated wholeRoutine immunisationDiscontinuedNot searched yetNCT04137887candidateId ctgov-quadrivalent-influenza-vaccine-split-virion-inactiva
Quadrivalent influenza vaccine, high-doseSanofi Pasteur, a Sanofi CompanyNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT04544267candidateId ctgov-quadrivalent-influenza-vaccine-high-dose-sanofi-past
Recombinant influenza vaccine (RIV4)Sanofi Pasteur, a Sanofi CompanyNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT05513391candidateId ctgov-recombinant-influenza-vaccine-riv4-sanofi-pasteur-a-
Trivalent inactivated influenza vaccineSanofiinactivated wholeRoutine immunisationDiscontinuedNot searched yetNCT00976027candidateId ctgov-trivalent-inactivated-influenza-vaccine-high-dose-sa
Vaccine Sanofi A(H1N1) 7.5 ugInstituto Nacional de Salud Publica, MexicoNot searched yetRoutine immunisationDiscontinuedNot searched yetNCT00989274candidateId ctgov-vaccine-sanofi-a-h1n1-15-ug-trivalent-instituto-naci

Antivirals

In use against this virus
NameMechanismUseStageJurisdictionsTrialsSource
ZanamivirRELENZANeuraminidase inhibitorTreatmentApprovedUS: approved—
quote
1 INDICATIONS AND USAGE RELENZA, an influenza virus neuraminidase inhibitor (NAI), is indicated for: Treatment of acute, uncomplicated influenza type A and B infections in patients aged 7 years and older who have been symptomatic for no more than 2 days.

Neuraminidase Inhibitor [EPC]; SPL id 571ce280-f506-436c-b378-d570cceae236 · verified 2026-10-30

Antibodies and immune globulins

Not searched yet. No US-approved antiviral antibody for this virus was found in the openFDA drug label endpoint.

Approval status is not a treatment recommendation. Dosing and eligibility are on the label and in national guidelines. This page does not give medical advice and does not render dosing. A development stage is not a measure of how well something works.

← All viruses · Countermeasure gaps

Cite this page. Influenza B virus. Vaccine Data Navigator, Open Source Medicine Foundation. Built 9 November 2026 from the ICTV Virus Metadata Resource (MSL41) and NCBI Taxonomy/GenBank. https://vaccinedatanavigator.org/virus-navigator/viruses/influenza-b-virus.html

Report an error