Question

1. The information below is from a box of typhoid vaccine.

VIVOTIF BERNA®

Typhoid Vaccine

Oral Ty 21a

Explain how you would know by simply reading this label that this is an attenuated vaccine. (Hint: Vivo means "life" in Latin and the little “a” does stand for attenuated, but these are not the answers I am looking for.)

2. Explain how the bacterium is attenuated in this vaccine and why this attenuation prevents the the bacteria in the vaccine from causing typhoid fever.

3. Explain why re-immunization with the Vivotif® vaccine is recommended every five years, but is recommended every two years for the Typhim Vi® vaccine. (Use your knowledge of immunology to answer this question).

Answer 1

1). We can say that the vaccine is attenuated live because the route of administration os oral. Killed vaccines are always administered through parental route, attenuated vaccines can also be administered through the parental route.

2). Vaccination is an immunization procedure in which a person develops immunity, particularly against a specific pathogen. Vaccines contain live attenuated or killed organisms that are injected to the person in a series. So, our body develops antibodies to those antigens and if that organism enters into our body, they readily attack the pathogen. Vaccination is type of acquired immunity.

Live, attenuated vaccines: These are produced by the attenuation of the pathogenicity of the virus or by administering the non-pathogenic relative viruses (eg: BCG vaccine, oral polio vaccine, oral typhoid vaccine). During attenuation process, the virulent agent is converted into a harmless, nonvirulent form, but the organism remains alive. So, the body recognizes the organism and develop antibodies against the organism.