TRENTON - After the recent recall of a crucial baby vaccine by one manufacturer, the only other U.S. supplier of the shots says it expects to be able to provide enough to cover U.S. demand for the first half of 2008.

However, Sanofi Pasteur officials declined to say how many doses that would total. They said the company, part of Paris-based drugmaker Sanofi-Aventis SA, is still determining whether it will be able to boost production of the Hib vaccine or shift some supply to the United States from the many other countries where it is sold.

The company said that some doctors likely will still see sporadic shortages and that it is still determining how much vaccine it can provide for the second half of next year. In a typical year, roughly 14 million doses are administered in the United States.

"Sanofi Pasteur still faces significant challenges in supplying Hib vaccine to meet demand," said the company, whose U.S. vaccine operations are based in Swiftwater, about 100 miles north of Philadelphia.

On Dec. 12, Merck & Co. Inc. said it was recalling 1.2 million doses of the vaccine, which protects against Haemophilus influenza type B. The virus, which is different than seasonal flu, can cause meningitis, pneumonia, and other serious infections, resulting in brain damage, deafness, and death in some babies.

Merck recalled the 1.2 million doses, and said it would not be able to supply any more until at least next fall because of a sterility problem discovered at its West Point manufacturing plant in October. It also quarantined nearly a year's worth of other, possibly suspect, doses, meaning nearly 2 years' worth of production will be discarded.

Merck, which employs more than 12,000 in Montgomery County, said the chances of individual vaccines being contaminated were low and that, at worst, a child would have experienced swelling and redness at the injection site.

But with Merck making half the U.S. supply of vaccine, fears of a prolonged shortage led to a crush of pediatricians trying to order it from Sanofi Pasteur, particularly those who saw their Hib vaccine stock wiped out by the recall. Sanofi Pasteur has been telling doctors to order only a reasonable monthly supply.

The vaccine is usually given in a two- or three-shot series - depending on the manufacturer - that starts when a child is 2 months old. That is followed by a booster shot at 12 to 15 months.

Last week, officials at the U.S. Centers for Disease Control and Prevention instructed doctors to defer giving the booster for the time being, as the American Academy of Pediatrics has advised its 60,000 members.

That change allowed Sanofi Pasteur to predict that its supply would cover demand through June.