Health officials in North Dakota are warning that some H1N1 flu vaccine used for health workers and vulnerable individuals might have frozen on its way to health clinics and other sites.
The Department of Health said Wednesday that about 1,100 doses of the injectable H1N1 vaccine were either frozen or reached temperatures below levels recommended for shipping. The affected doses make up less than 5 percent of the total injectable and Flumist vaccine the state had received so far--just over 24,000 doses. Health officials had given a previous estimate of 1,700 affected doses.
Some officials receiving the vaccine shipments called the health department after seeing that the freeze indicator on the packages was out of range. The health department then notified providers on Monday about the frozen vaccine, and said 150 or so people should get revaccinated because of concern that the vaccine they received wasn't effective. The rest of the affected vaccine won't be used.
"There's no issue with the safety of the vaccine, but we are concerned about the effectiveness of the vaccine," said Tim Wiedrich, who oversees emergency preparedness and response for the health department.
Wiedrich said there are a variety of things that could have led to the frozen vaccine, including the outside air temperature, the shipping package's insulation and the location of the temperature monitors within the package.
"We're still looking into that situation," he said.
North Dakota received the vaccine this month, repackaged it on Oct. 14 and sent it to 99 providers across the state. Thirty providers said the temperature indicators showed the vaccine was frozen. Officials are still checking with six other providers.