North American Vaccine Inc. waited nearly three years for FDA approval of Certiva, its combined diphtheria, tetanus and acellular pertussis (DTaP) vaccine. Now the issue is how NVX will persuade physicians to adopt its vaccine over the three DTaP vaccines already marketed in the U.S.

Certiva will compete against SmithKline Beecham's Infanrix, Connaught Laboratories Inc.'s Tripedia and Wyeth-Ayerst Laboratories' Acel-Imune. NVX estimates the U.S. market for DTaP vaccines at $300 million.