A hospital in New York has alerted over 4,000 of its patients that they may have possibly been infected with human immunodeficiency virus (HIV) and hepatitis after receiving insulin from an insulin pen reservoir that was possibly used more than once.

The South Nassau Communities Hospital on Long Island sent out letters to 4,247 patients advising them to get tested for hepatitis B and C and HIV as there is risk they have been infected with the diseases through an insulin pen.

"Working closely with the New York State Department of Health, South Nassau is voluntarily notifying a specific group of patients that may have received insulin from an insulin pen reservoir (not the pen's single-use disposable needle) that may have been used with more than one patient," the hospital said in a statement.

While the insulin pen may have been used more than once, hospital officials said that the needles were not reused and the risk of infection is low. The Centers for Disease Control and Prevention (CDC), however, said that using insulin pens for more than one person could lead to blood borne pathogen transmission regardless if the needle is changed.

"Insulin pens must never be used for more than one person," the CDC said. "Regurgitation of blood into the insulin cartridge can occur after injection creating a risk of bloodborne pathogen transmission if the pen is used for more than one person, even when the needle is changed."

South Nassau said it already prohibits the use of insulin pens and now allows only single-use vials for administering insulin to patients. The hospital also offered confidential and free blood testing as well as set up a dedicated phone number so the affected patients can easily schedule for a blood test after they received the letter.

"The hospital is recommending that patients receiving the notification be tested for hepatitis B, hepatitis C and HIV. While the testing is voluntary, it is recommended," the hospital said. "To facilitate the process, the hospital is offering the patients free and confidential blood testing services. It has established a dedicated toll-free telephone number that the patients may call to schedule a blood test within 60 days after receiving the letter."

Hospital spokesman Damian Becker said that the letters were sent out in phases but should all be received by March 17.