On Oct. 15, 1999, Wyeth-Lederle Vaccines announced that it was withdrawing the Rotashield vaccine from the market and requested the immediate return of all distributed doses. Rotashield was a live, attenuated rhesus rotavirusbased tetravalent vaccine (RRV-TV).

On August 31, 1998, the Advisory Committee on Immunization Practices (ACIP) had recommended routine immunization with three oral doses of RRV-TV for infants at age two, four and six months of age for the prevention of rotavirus disease in the United States.

By the beginning of October 1999, 101 confirmed and presumed cases of intussusception had been reported to Vaccine Adverse Event Reporting System (VAERS). The rate of reporting increased greatly after the July 1999 announcement of the temporary postponement of rotavirus vaccination. Fifty-two patients required surgery, nine required bowel resection and one patient died.

These events demonstrate very clearly that postmarketing surveillance was an essential component of vaccine program implementation.