Immunogenicity and efficacy of the monovalent, trivalent and quadrivalent intranasal live attenuated influenza vaccines containing different pdmH1N1 strains.

•Efficacy against H1N1 of mono, tri and quadrivalent formulations of the LAIV was studied in ferrets.•Complete protection from virus replication of H1N1 in the lungs was observed with all formulations.•The A/Mich vaccine strain showed higher immune titres and efficacy than A/Cal vaccine strain.•Monovalent formulation was more effective compared to the tri and quadrivalent formulations.•Monovalent formulation would be the best candidate during a pandemic.