Fairfax County heath officials this week discontinued use of a new Italian vaccine several days after receiving warnings about possible defects with the serum, but not before several preschoolers had suffered adverse reactions from it.

The drug, produced by Sclavo Biologicals Inc., an Italian-owned firm in Wayne, N.J., is designed to protect against tetanus and the major childhood diseases of diphtheria and whooping cough.

Starting in June, the firm supplied Fairfax County through the state of Virginia's immunization program with two batches of about 75 doses each. Both batches eventually proved defective, health officials said yesterday.

County health officials were first told Sept. 1 by the Atlanta-based Center for Disease Control (CDC) that six states were reporting cases of adverse reactions to the serum. The reactions, a CDC spokesman said yesterday, consisted of lump-like skin swellings and redness at the site of the injection.

The county however, continued use of the Sclavo vaccine through Sept. 5, when the firm agreed with federal officials to stop distributing the vaccine.

By then, at least two preschoolers had suffered adverse reactions in Fairfax County, assistant county health director John Einarson said yesterday The county received another batch of the vaccine Sept. 12 to replace the earlier lot, but ceased using it Friday after Sclavo, reacting to new reports of adverse reactions, stopped distributing the drug.

The second batch had produced only one report of an adverse reaction in Fairfax County, Einarson said. Nevertheless, that figure seemed "rather excessive", Einarson said, adding that he was "sure" there were more instances in the county of adverse reactions to the vaccine.