A/Missouri/11/2025 (H1N1)pdm09-like strain (A/Switzerland/6849/2025, IVR-278); A/Singapore/GP20238/2024 (H3N2)-like strain (A/Singapore/GP20238/2024, IVR-277); B/Austria/1359417/2021-like strain (B/Michigan/01/2021, wild type); B/Phuket/3073/2013-like strain (B/Phuket/3073/2013, wild type)