the MLVs were generally effective against homologous strains but variable in success against heterologous strains ,
and the outcomes of inactivated vaccines in the field are not very promising .
the MLVs were generally effective against homologous strains but variable in success against heterologous strains , and the outcomes of inactivated vaccines in the field are not very promising .
the MLVs were generally effective against homologous strains but variable in success against heterologous strains , and the outcomes of inactivated vaccines in the field are not very promising .