Anvisa (National Health Surveillance Agency) has identified the strains (types of viruses) that should be included in vaccines against influenza, influenza virus, which will be used in Brazil in 2026.
Changing the composition of strains is key to vaccine effectiveness, as the virus adapts and mutates. The World Health Organization (WHO) regularly analyzes all frequently circulating influenza virus subtypes, to improve the effectiveness of immunization.
Every year, Anvisa, in accordance with the World Health Organization, publishes the composition of influenza vaccines that will be used the following year. The 2026 composition is published in Standard Instruction 408/2025.
Southern Hemisphere Vaccines (2026 season)
Vaccines destined for the Southern Hemisphere and used in Brazil as of February 1, 2026 must contain the following:
• Triple vaccines: Strains similar to A/Missouri/11/2025 (H1N1)pdm09, A/Singapore/GP20238/2024 (H3N2), and B/Austria/1359417/2021 (Victoria strain).
• Quadruple vaccines: In addition to these three, adding a strain similar to the B/Phuket/3073/2013 strain (Yamagata strain).
• Non-egg-based vaccines: Strains equivalent to A/Missouri/11/2025 (H1N1)pdm09, A/Sydney/1359/2024 (H3N2), and B/Austria/1359417/2021 (Victoria strain).
Vaccination labels must state: “CEPAS 2026 SOUTHERN HEMISPHERE”.
Northern Hemisphere Vaccines (2025-2026 season)
Vaccines with strains recommended for the Northern Hemisphere are intended exclusively for the Ministry of Health’s campaigns for specific regions of the country. It must contain:
• Triple vaccines: strains similar to A/Victoria/4897/2022 (H1N1)pdm09, A/Croatia/10136RV/2023 (H3N2), and B/Austria/1359417/2021 (Victoria strain).
• Quadrivalent vaccines: Addition of a strain similar to B/Phuket/3073/2013 (Yamagata strain).
• Non-egg-based vaccines: Strains equivalent to A/Wisconsin/67/2022 (H1N1)pdm09, A/District of Columbia/27/2023 (H3N2), and B/Phuket/3073/2013 (Yamagata strain).
In these cases, the posters must contain the expression: “CEPAS 2025-2026 NORTHERN HEMISFÉRIO”.
Quadrivalent vaccines
Anvisa warns that the WHO recommendation also foresees stopping the use of quadrivalent versions of the seasonal influenza vaccine from 2027. According to the agency, the decision is linked to the absence of confirmed records of the natural course of the B/Yamagata strain – exclusive to quadrivalent immunization devices – since 2020.
However, the organization stresses that a transition period may be necessary until the final withdrawal of these immunizations takes place, depending on the regulatory assessment and operational capacity of each country.
In the case of Brazil, after analyzing the current availability of registered trivalent and quadrivalent seasonal influenza vaccines on the market, Anvisa considered it necessary to maintain supplies of the quadrivalent versions throughout 2026. An immediate withdrawal could jeopardize vaccination coverage nationally, both in public and private networks, as the markets are not equally supplied with both versions.