Researchers of a recent retrospective study evaluated 71 patients with multiple myeloma (MM) receiving the 2020/2021 quadrivalent influenza vaccine; 52 opted for a second (“prime-boost”) dose approximately 29 days later. Hemagglutination inhibition (HAI) titers were measured pre-vaccination, pre-dose-2, and 3 to 4 weeks after dose-2 (or 6–8 weeks after a single dose).
