Two employees of a Chicago-based company knowingly shipped to its customers syringes that had not been sterilized.
A universal flu vaccine has been successfully tested on humans with the disease for the first time, it was reported Monday.
The U.K.'s Guardian newspaper said that unlike existing vaccines, this one, which was tested by scientists at Britain's Oxford University, does not need to be changed every year to match the latest strain of the virus.
The Guardian said when a new strain of flu emerges it takes at least four months to develop a new vaccine, during which time people get sick and some die.
In 1918, a particularly dangerous form of flu developed in Europe and then spread across the world, killing an estimated 50 million people, about 3 percent of the world's population at the time.
Dr. Sarah Gilbert, who led the Oxford research team, told The Guardian using the same vaccine every year would mean protecting against flu would "be more like vaccinating against other diseases like tetanus."
"It would become a routine vaccination that would be manufactured and used all the time at a steady level. We wouldn't have these sudden demands or shortages — all that would stop," she added.
Healthy people infected
The Guardian said Gilbert had infected 22 healthy volunteers with the Wisconsin strain of the H3N2 influenza A virus. Half had been given the new vaccine, the others had not.
"Fewer of the people who were vaccinated got flu than the people who weren't vaccinated," she told the paper.
She also said that T-cells, part of the body's immune system, were more active in those who had been given the vaccine.
"The volunteers we vaccinated had T-cells that were activated, primed and ready to kill," Gilbert said.
"This is the first time anyone's tested if you can boost somebody's T-cell response to flu and, having done that, if it helps protect against getting flu. It's the first time anybody's done that in people," she added.
Adrian Hill, director of the university's Jenner Institute, where the research was carried out, told the paper the trial had showed the vaccine was safe.
The next step, he told the Guardian, was "probably" to combine it with existing flu vaccines, which would give protection against that season's type of the disease and also prime the immune system for future years.
"It may not be 100 percent effective against all strains, but at least if there were a pandemic coming around, it would cover you for any strain," he added.
Traditional flu vaccines work on 70-80 percent of young people, but just 30-40 percent of elderly people.
Hill told the paper that they planned to carry out a trial among elderly people to see if the new vaccine would "hopefully double that."
Mark Fielder, a medical microbiologist at Kingston University in the U.K., told The Guardian the study had "some potentially very exciting findings," saying it might have implications for "infectious disease in a wider context."
Professor Hugh Pennington, former president of the U.K.'s Society of General Microbiology, told msnbc.com that it was an "interesting development," but cautioned it was a "small study."
"I'm just reserving my judgement until they've got a bigger study," he said. "We should wait and see how things develop rather than saying this is the breakthrough we have been waiting for for 100 years."
However, echoing Fielder, Pennington added it could be "very, very interesting" because of the potential implications for other infections as well.