British officials say they warned the U.S. government last month that problems at a drug manufacturing plant could disrupt influenza vaccines to the United States.
According to a report in Saturday's Washington Post, British Department of Health officials say they notified their American counterparts of a possible shortage on September 13, after drug maker Chiron announced four million doses of the vaccine were contaminated.
The shortfall of almost one half of available flu vaccines caught U.S. health agencies off guard last Wednesday, forcing states to ration the available supply for high-risk individuals, such as children and the elderly.
Experts say the shortage stems from the United States having just two suppliers and leaving the provision of vaccines, an issue of public health, to private companies.