Health
Flu vaccine effective at half-dose for healthy people younger than 50
NEWS IN BRIEF — Posted Dec. 29, 2008
Half-doses of flu vaccine appear to be as effective as full doses among individuals younger than age 50, according to a study in the Dec. 8/22, 2008 Archives of Internal Medicine.
The finding could prove useful should another vaccine shortage arise. Production problems that developed as the 2004-05 influenza season got under way resulted in long lines for scarce vaccine, with some people having to forgo a shot.
Researchers conducted a randomized clinical trial involving healthy adults ages 18 to 64. Between November and December 2004, 554 adults received a full dose of influenza vaccine and 556 received a half-dose. Blood samples were taken before and 21 days after vaccination and tested for antibodies against the flu.
Responses to both doses were similar for those ages 18 to 49, said the researchers. Older recipients of a half-dose did not respond as well as did those receiving the full dose. However, women of all ages had a greater response to both doses of the vaccine than did men. This finding led the researchers to suggest that vaccine guidelines be modified to take sex and age into consideration.
Note: This item originally appeared at http://www.ama-assn.org/amednews/2008/12/29/hlbf1229.htm.
