Sunday, August 10, 2008

Hepatitis A vaccine for post-exposure prevention

(In case you're wondering what all this vaccine information is about, I am preparing a workshop on immunizations, so my brain's shot full of shots.)

In a recent post, I mentioned that hepatitis A immune globulin (IG) is the preferred approach for the prevention of infection in folks who've been exposed to the disease through household contacts or 'fecal fingers'. My information, I discover, is running about 10 months behind the times.

Last October, researchers published a study in the NEJM (1) comparing the use of HAV vaccine with IG in persons ages 1-40 exposed to hepatitis A. The two groups were randomized to receive one therapy or the other within 2 weeks of viral exposure. Few subjects developed hep A no matter which shot they received, and the CDC concluded that the two strategies were equally efficacious.

As a result, they now officially recommend the HAV vaccine for postexposure (less than 2 weeks) prophylaxis in this age range as 1) it's less painful, 2) it's more widely available, and 3) the shot provides longterm immunity. Older persons or people with chronic liver disease tend to be sicker with hepatitis A, so the CDC continues to recommend IG for them. What they really recommend, however, is that all children get this shot after age 1, and most adults should consider receiving a shot as well so they can eat unwashed lettuce with impunity and immunity.
(1)Victor JC et al. Hepatitis A vaccine versus immune globulin for postexposure prophylaxis. N Engl J Med 2007 Oct 25; 357:1685.

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