APA (7th ed.) Citation

KA, S. (2003). How contagious is vaccinia? New England Journal of Medicine, 348(5), 439.

Chicago Style (17th ed.) Citation

KA, Sepkowitz. "How Contagious Is Vaccinia?" New England Journal of Medicine 348, no. 5 (2003): 439.

MLA (9th ed.) Citation

KA, Sepkowitz. "How Contagious Is Vaccinia?" New England Journal of Medicine, vol. 348, no. 5, 2003, p. 439.