Pfizer buys controlling stake in herpes vaccine developer Redvax, strengthening its arsenal

Pfizer continued its aggressive push into the development of new vaccines, announcing the acquisition of a controlling stake in Switzerland's Redvax GmbH on Monday.

The privately-held company is working on a herpes vaccine for human cytomegalovirus, known as CMV, which infects between 50 percent and 90 percent of adults, according to Pfizer, most of whom show no symptoms.

Pregnant women are at higher risk of infection and can pass it on to a fetus, which could cause hearing loss or neurological disorders. In the U.S., about 5,000 children are born every year with health problems cause by CMV, Pfizer said.

Pfizer Inc. spent $635 million last month on two vaccines made by Baxter International Inc. as the New York pharmaceutical builds out its portfolio.

Pfizer is in a race with Novartis to develop a new meningitis vaccine and both companies snagged the coveted breakthrough therapy designation from federal regulators last year.

Redvax is a spinoff of privately-held Swiss biopharmaceutical company Redbiotec AG.