April 15, 2013 – Patients who received the vaccine and then developed an infection after undergoing surgery were more likely to die than patients who received the placebo and developed an infection after surgery.
A significant concern with performing cardiothoracic surgery is the risk of the patient developing an infection from Staphylococcus aureus bacteria, the most common cause of staph infections. The infections can cause serious complications and even death, but developing a safe vaccine to protect against S aureus has been unsuccessful to date. A recent phase IIb/III clinical trial to test the safety and effectiveness of a new vaccine terminated enrollment early after the data monitoring committee found evidence of possibly higher mortality rates and organ failure, and little benefit, among patients who received the study vaccine compared with the placebo group.
The results of the vaccine trial were published in the April 3 issue of the Journal of the American Medical Association. The DCRI’s Vance Fowler, MD, MHS, was the lead author, and Ralph Corey, MD, was also an author.
For the trial, the researchers compared a potential new vaccine, V710, with a placebo in patients who were going to have cardiothoracic surgery with an incision in the sternum. Patients were randomly assigned to receive a single injection of the vaccine or placebo between 14 and 60 days prior to undergoing surgery.
The researchers had planned to enroll more than 8,030 patients, but enrollment stopped after 7,983 patients had received the vaccine or placebo. The vaccine was not found to be significantly more effective than the placebo at preventing deep sternal wound infections, and patients who received the vaccine were significantly more likely to have an adverse reaction at the injection site within the first 14 days compared with patients who received the placebo.
Although mortality rates were not significantly different in the two patient groups, patients who received the vaccine and then developed an S aureus infection after undergoing surgery were more likely to die than patients who received the placebo and developed an infection after surgery. Patients who received the vaccine were more likely to develop methicillin-resistant S aureus (MRSA) infections compared with patients who received the placebo. Mortality rates associated with MRSA infections are higher than for surgical site infections.
Based on the trial results, the researchers do not recommend using the V710 vaccine for patients who need to have cardiothoracic surgery.