(NEWSER) – More than 4,000 people on Long Island are getting the most unwelcome kind of letter from a local hospital—a warning that they might have been inadvertently exposed to HIV. As ABC News explains, the risk is low, but it stems from improper use of an insulin pen. It seems a nurse at South Nassau Communities Hospital was overheard saying, incorrectly, that it was OK to reuse the pen on multiple patients, reports Newsday via NBC News.

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