What does the bubonic plague vaccine have and how effective is it?

Bubonic plague vacci: Plague caused by bacteria Yersinia pestis, , the vaccine is prepared from Y pestisorganism grown in artficial media, inactivated with formaldehyde and preserved in 0.5%phenol.The vaccine contains trace amounts of beef-heart extract, yeast extract, agar andpeptones and peptides of soya and casein.After 3 injections of vaccines 7%do not produce antibodies, few develop low titer, so booster doses may be.