Since there has been no detection of the naturally occurring B/Yamagata-lineage influenza virus since 2020, the opinion of the World Health Organization (WHO) influenza vaccine composition advisory committee is that the inclusion of B/Yamagata-lineage antigens in influenza vaccines is no longer warranted.
WHO recommends trivalent or quadrivalent influenza vaccines.
WHO Q&A on recommendations for 2024 south hemisphere composition of influenza vaccines