But the stepped-up demand from businesses is aggravating a vaccine shortage that’s left some high-risk patients, as well as some companies, clamoring for their shots. A slow-growing strain in this year’s vaccine (it’s updated annually by the Centers for Disease Control) caused delays in delivery of the 75 million doses. General Motors doesn’t expect to get its vaccine until mid-November, more than a month late. That’s a problem because the start of the flu season coincides with the end of the calendar year, when GM is trying to hit annual production targets. “It’s a critical time,” says GM health-care spokesman Robert Minton. “Anything that impacts the workers and their ability to do their jobs is a business concern.” And that’s nothing to sneeze at.