Which statement describes a major difference in the epidemiology of HBV and HIV, as discussed?

• A. HBV is more easily transmitted through needle punctures.
• B. HIV is more easily transmitted through needle punctures.
• C. HBV cannot be transmitted through needles.
• D. HIV cannot be transmitted through needle punctures.

Answer: (A)

The key idea is that percutaneous exposure carries a much higher risk for hepatitis B than for HIV. The likelihood of infection after a needlestick from a source with hepatitis B can be quite high—roughly around 6% if the source is HBeAg-negative, and up to about 30% if the source is HBeAg-positive. In contrast, the average risk after a needle-stick with an HIV-positive source is about 0.3%. So hepatitis B is far more easily transmitted through needle punctures. This difference in per-exposure infectivity is what drives the observed epidemiology. It’s also why vaccination against hepatitis B is so important and effective in preventing transmission, whereas HIV has no vaccine (though post-exposure prophylaxis can reduce risk if started promptly).