It is recommended that quadrivalent vaccines for use in the 2018-2019 northern hemisphere influenza season contain the following:

• an A/Michigan/45/2015 (H1N1)pdm09-like virus;
• an A/Singapore/INFIMH-16-0019/2016 (H3N2)-like virus;
• a B/Colorado/06/2017-like virus (B/Victoria/2/87 lineage); and
• a B/Phuket/3073/2013-like virus (B/Yamagata/16/88 lineage).

It is recommended that the influenza B virus component of trivalent vaccines for use in the 2018-2019 northern hemisphere influenza season be a B/Colorado/06/2017-like virus of the B/Victoria/2/87-lineage.