The MRHA has approved Sanofi Pasteur MSD UK's quadrivalent influenza vaccine, which contains two A strains (A/H1N1 and A/H3N2) and two B strains (B/Victoria and B/Yamagata) of the virus.

The majority of seasonal influenza vaccines in the UK are currently trivalent, meaning that they help protect against three strains of the influenza vaccine; two A strains and a single B strain. However, in the UK's 2015-2016 flu season 94 percent of influenza B cases belonged to the B/Victoria lineage. This lineage was only included in quadrivalent formulations and not included in the trivalent vaccines recommended by the World Health Organization.
"Inclusion of the second B strain in quadrivalent influenza vaccines can help to provide broader protection by minimising the impact of a mismatch of vaccine and disease-causing strains," Sanofi Pasteur MSD said in a statement.
The company added that if quadrivalent vaccines were used in the UK over the past decade, it has been estimated that an additional quarter of a million influenza cases could have been avoided, including 5,940 influenza-related hospitalisations and 3,955 influenza-related deaths.
Sanofi Pasteur MSD said that it anticipates that quadrivalent vaccines will become a new standard in the prevention of influenza and is committed to working with healthcare professionals to help protect eligible populations.