Vaccination of influenza a virus decreases transmission rates in pigs

Romagosa, Anna; Allerson, Matt; Gramer, Marie; Joo, Han Soo; Deen, John; Detmer, Susan; Torremorell, Montserrat

With the detection of new influenza subtypes in the last decade (i.e. H1N1, H1N2 and H3N2 triple reassortant viruses) [6] [7] [8] in pigs and the recent appearance of the 2009 pandemic H1N1, both human and animal health officials have paid greater attention to flu in pigs due to the role that pigs play in inter-species transmission [9] . The control of influenza in pigs is often accomplished by the use of vaccines [10] . Both inactivated licensed commercial vaccines and autogenous licensed inactivated vaccines are commonly used in pigs. Commercial vaccines confer protection against flu infection and disease presentation but often this protection is only partial [11] [12] [13] . Commercial vaccines usually include one or more isolates representative of the strains in a region but they may not always confer protection against the isolate infecting a specific farm or population. On the other hand, autogenous vaccines may be prepared with the isolate or isolates recovered from a specific production system and restricted to use in only that system. These vaccines have gained popularity in the US in the past few years. Although vaccination can result in the reduction of clinical signs and virus shedding, limited information is available on the effect that vaccination has on population susceptibility, the spread of infection and how vaccination may prevent transmission to other species [14] .