Alice Peck Day Memorial Hospital in Lebanon, N.H., is urging 827 patients to be revaccinated after discovering vaccines at its pediatric clinic were periodically stored outside the acceptable temperature range from September 2014 to October 2015.
Vaccines need to be stored at certain temperatures to maintain potency, and the hospital is concerned that some pediatric patients may have received ineffective vaccines.
A state survey in August 2015 uncovered the problem, and the hospital has been working with the state since the problem was discovered.
"Although there have been no instances of patients reporting a vaccine-preventable disease after receiving an immunization at our clinic, patient safety is our first concern and we have worked diligently to identify all vaccines for which we could not prove integrity with absolute certainty," Sue Mooney, MD, the hospital's president and CEO, said in a statement.
The hospital has sent letters to patients for whom revaccination is recommended and also to whom revaccination is not necessary. The new vaccinations are being offered for free.
Since the problem was discovered, the hospital implemented a new vaccine management plan and replaced backup thermometers. One new feature is a system that will page staff if refrigerators stray from normal temperatures.
"We are very sorry this incident occurred," Dr. Mooney said. "We will do everything feasible to assure nothing like this happens again."