"I think it's premature to get too worried at this stage," the pharma executive said from the PhRMA Conference in San Diego. "At this time we don't see any human to human infection being passed."
He told CNBC that China has made huge progress in its public health care system and is much better placed to evaluate the outbreak.
"We've had a few of these scares before, so people know where to look," Viehbacher said.
The fact that poultry sales are being restricted is also a good sign, and an evolution in agricultural practices could also help limit the risk, he said.
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Sanofi is also working on a "universal" flu vaccine that might mean only one flu shot with booster shots every few years.
"Right now, the issue is the flu virus that comes along every year is not exactly the same," he said. That means people need to get a flu shot every year to be protected.
A universal flu vaccine may be still more than five years away, he said.