Trends in intussusception hospitalizations among US infants before and after implementation of the rotavirus vaccination program, 2000-2009

Background. Although US data have not documented an intussusception risk with current rotavirus vaccines, international data indicate a possible low risk, primarily after the first dose. Methods. Among infants in 26 US states comprising 75 of the birth cohort, we examined age-specific trends in population-level intussusception hospitalization rates before (2000-2005) and after (2007-2009) rotavirus vaccine introduction. Results. Compared with 2000-2005 (35.3 per 100 000), the rate was greater in 2007 (39.0 per 100 000; rate ratio [RR], 1.10; 95 confidence interval [CI], 1.04-1.18), similar in 2008 (33.4 per 100 000; RR, 0.95; 95 CI,. 89-1.01), and lower in 2009 (32.9 per 100 000; RR, 0.93; 95 CI,. 87-.99). Among infants aged 8-11 weeks, compared with 2000-2005 (6.9 per 100 000), a small, significant increase was observed in each of 2007 (11.4 per 100 000; RR, 1.64; 95 CI, 1.08-2.50), 2008 (12.2 per 100 000; RR, 1.76; 95 CI, 1.17-2.65), and 2009 (11.0 per 100 000; RR, 1.59; 95 CI, 1.04-2.44). Conclusions. Following rotavirus vaccine introduction, a small increase in intussusception rates was seen among US infants aged 8-11 weeks, to whom most first doses of vaccine are given; no sustained population-level change in overall rates was observed.