Prolonged interval maintenance venom immunotherapy

Current guidelines recommend indefinite administration of venom immunotherapy at 4-week intervals. To simplify this therapy, we examined the clinical and immunologic response after extending the interval between maintenance venom injections to 6, 8, and 12 weeks. Twenty-six patients who had had sting anaphylaxis and positive skin tests received maintenance bee or yellow jacket venom immunotherapy at greater or equal to 6-week intervals. This extended interval was started after a prior average 4-week maintenance interval of 2.3 years. Injections were given at 6-week intervals to all 26 patients and extended to 8-week intervals in 10, and 12-week intervals in 3 patients. Following venom injections, there were 14 mild local reactions and no systemic reactions. No adjustment in dosing was necessary. While on prolonged interval maintenance venom immunotherapy, there were 17 re-stings in 12 patients with no systemic reactions. During prolonged interval maintenance venom immunotherapy, either the serum venom-specific IgG increased or the already elevated titers remained the same in 18 patients and decreased in 2. In the others, preexisting titers were low and unchanged. Serum venom-specific IgE tended to slowly decrease. These clinical and immunologic data suggest that a 4-week maintenance interval may be safely extended.