An O’Hara company that is growing at better than a 50 percent annual clip is not looking to slow down now that its parent is being swallowed up by a $2.2 billion acquisition. Zoll Medical’s LifeVest business has 385 employees and 115 contract workers at its new offices in RIDC Park. Another 190 employees work outside the region, for a total head count of 690. That’s up from about 400 employees and contract workers a year ago.
