General information, not an individual diagnosis. Ask a healthcare professional if you are unsure about your situation.
Trivalent means a flu vaccine contains antigens from three virus strains. Quadrivalent means four. These words count viral components; they do not determine how many injections a vaccination programme requires.
Moving from four components to three removes the B/Yamagata lineage: two type A components and one type B component remain. This is a specific change in composition, separate from choosing strains for each season.
HAS explains that B/Yamagata has not been detected since March 2020. This is the reason for the recommended removal: retaining that component was no longer justified by the circulation observed.
WHO recommended the removal in February 2024, followed by the European Medicines Agency’s recommendation for the 2025-2026 transition. The official ANSM document updated on 3 August 2026 does describe three strains for the 2026-2027 season; these steps have different dates.
Valency answers ‘how many components?’. Seasonal composition answers ‘which strains?’. Returning to three therefore does not mean that formulations are identical across seasons.
If packaging or an article still mentions four strains, keep its name and date to discuss with a professional. Ask which season and formulation it concerns; the strain count does not let you choose a vaccine on your own.
Sources
Vaccination
Flu and Covid-19: the 2026–2027 campaign
The national flu and Covid-19 vaccination campaign starts on 13 October 2026. In Doctolib, choose “Vaccination antigrippale (Grippe)” or “Vaccination COVID-19” for the vaccination you want to discuss.
Bring your carte Vitale and, for flu, your coverage voucher if you have one. The professional checks the recommendations and coverage conditions that apply to you.
The pharmacy checks whether vaccination and coverage apply based on the vaccine, your age and your circumstances.
Assurance Maladie — Campagne grippe 2026–2027 (9 octobre 2026) · Assurance Maladie — Campagne Covid-19 (30 septembre 2026) · Assurance Maladie — Vaccination par le pharmacien · Assurance Maladie — Prise en charge des vaccins · Ministère de la Santé — Calendrier vaccinal
Your health review
Review your health
Mon bilan prévention is an appointment to discuss your habits and choose your health priorities. Review the four age groups and practical information.