Seasonal Flu Quad

About Seasonal Flu Quad

Seasonal influenza vaccines were upgraded from trivalent to quadrivalent in the 2010s. Trivalent vaccines protected against two A strains and one B strain. Quadrivalent vaccines added a second B strain, improving coverage. After the B Yamagata lineage stopped being detected following 2020, many countries returned to trivalent vaccines from 2024. Flu vaccine production relies primarily on chicken eggs, a technology developed in the 1940s. Hundreds of millions of eggs are used annually for flu vaccine production. Cell culture and recombinant protein technologies offer faster production and avoid egg adaptation issues. Flucelvax, the first cell culture flu vaccine, was licensed in the US in 2012. Flublok, a recombinant vaccine, was licensed in 2013. These technologies are particularly important for pandemic preparedness as they can be scaled quickly. Universal flu vaccine candidates targeting conserved viral proteins are in clinical trials.