The other type is virulent (produces disease), is the cause of FIP, and is called feline infectious peritonitis virus (FIPV). It is believed that FIP occurs when FECV mutates to FIPV in the cat and starts to replicate in the cat's cells. What causes this mutation is unknown.he other type is virulent (produces disease), is the cause of FIP, and is called feline infectious peritonitis virus (FIPV). It is believed that FIP occurs when FECV mutates to FIPV in the cat and starts to replicate in the cat's cells. What causes this mutation is unknown.
How long does a typhoid shot last?   According to the CDC website, a booster dose is needed every 2 years for people who remain at risk.. The oral (live) vaccine lasts 5 years before another dose is neededâ¦.
Typhoid vaccines are vaccines developed to prevent typhoid fever. There are two effective types available: 1  Ty21a, which is a live vaccine given orally. 2  Vi capsular polysaccharide vaccine, which is an injectable subunit vaccine.oosters are recommended every 5 years. The Vi capsular polysaccharide vaccine is licensed for use from age two years and older, and boosters are required every three years.