Which combination of diseases currently lacks vaccines?

• A. Hep A and Hep B
• B. Hep B and Hep C
• C. Hep C and HIV
• D. Hep A and HIV

Answer: (C)

Not all infectious diseases have vaccines; currently, vaccines exist for Hepatitis A and Hepatitis B, but none are available for Hepatitis C or HIV. The Hepatitis A vaccine is an inactivated-virus vaccine, and the Hepatitis B vaccine is a recombinant protein vaccine. In contrast, Hepatitis C is challenging to vaccine against because of its many genotypes and the virus’s ability to evade the immune response, making broadly protective immunity hard to achieve. HIV presents similar hurdles: the virus mutates rapidly, exists in diverse strains, and can hide in latent reservoirs, complicating efforts to elicit a durable protective response. Because the two diseases without licensed vaccines are Hepatitis C and HIV, that combination is the one lacking vaccines.