Effect of an Investigational Vaccine for Preventing Staphylococcus aureus Infections After Cardiothoracic Surgery: A Randomized Trial

IMPORTANCE Infections due to Staphylococcus aureus are serious complications of cardiothoracic surgery. A novel vaccine candidate (V710) containing the highly conserved S aureus iron surface determinant B is immunogenic and generally well tolerated in volunteers. OBJECTIVE To evaluate the efficacy and safety of preoperative vaccination in preventing serious postoperative S aureus infection in patients undergoing cardiothoracic surgery. DESIGN, SETTING, AND PARTICIPANTS Double-blind, randomized, event-driven trial conducted between December 2007 and August 2011 among 8031 patients aged 18 years or older who were scheduled for full median sternotomy within 14 to 60 days of vaccination at 165 sites in 26 countries. INTERVENTION Participants were randomly assigned to receive a single 0.5-mL intramuscular injection of either V710 vaccine, 60 μg (n = 4015), or placebo (n = 4016). MAIN OUTCOME MEASURES The primary efficacy end point was prevention of S aureus bacteremia and/or deep sternal wound infection (including mediastinitis) through postoperative day 90. Secondary end points included all S aureus surgical site and invasive infections through postoperative day 90. Three interim analyses with futility assessments were planned. RESULTS The independent data monitoring committee recommended termination of the study after the second interim analysis because of safety concerns and low efficacy. At the end of the study, the V710 vaccine was not significantly more efficacious than placebo in preventing either the primary end points (22/3528 V710 vaccine recipients [2.6 per 100 person-years] vs 27/3517 placebo recipients [3.2 per 100 person-years]; relative risk, 0.81; 95% CI, 0.44-1.48; P = .58) or secondary end points despite eliciting robust antibody responses. Compared with placebo, the V710 vaccine was associated with more adverse experiences during the first 14 days after vaccination (1219/3958 vaccine recipients [30.8%; 95% CI, 29.4%-32.3%] and 866/3967 placebo recipients [21.8%; 95% CI, 20.6%-23.1%], including 797 [20.1%; 95% CI, 18.9%-21.4%] and 378 [9.5%; 95% CI, 8.6%-10.5%] with injection site reactions and 66 [1.7%; 95% CI, 1.3%-2.1%] and 51 [1.3%; 95% CI, 1.0%-1.7%] with serious adverse events, respectively) and a significantly higher rate of multiorgan failure during the entire study (31 vs 17 events; 0.9 [95% CI, 0.6-1.2] vs 0.5 [95% CI, 0.3-0.8] events per 100 person-years; P = .04). Although the overall incidence of vaccine-related serious adverse ev