USA Today reports that the Centers for Disease Control and Prevention (CDC) has confirmed three cases of a new flu virus, which originated in pigs but apparently spread from person to person, in three Iowa children. However, flu experts comment that there is no reason to fear that this might be the beginning of a new pandemic.

Experts comment, "We have known that swine viruses get into humans occasionally, transmit for a generation or two and then stop. The issue is whether there will be sustained transmission (from person to person) - and that nearly never happens."

The CDC has counted a total of 18 cases of this new virus, an influenza A strain known as S-OtrH3N2, in two years. That suggests that it's not spreading quickly or easily, says William Schaffner, a professor at the Vanderbilt University School of Medicine and spokesman for the Infectious Diseases Society of America.

Schaffner notes that flu viruses mutate and swap genes all the time. Infectious disease experts may only be noticing these new viruses because of better technology, he says. The USA's beefed-up state medical labs, which have lots more firepower than before 2001, are much better at spotting novel viruses, which in the past might have gone unnoticed.

Thanks to the sophistication of these labs, scientists are getting a window into the inner workings of the flu that they haven't had in the past. But that doesn't mean that these novel viruses are necessarily any more dangerous.

The H1N1 swine flu pandemic began in 2009 after flu viruses mutated to create a new strain that humans had never encountered before, leaving everyone vulnerable to infection. Although the H1N1 pandemic proved to be relatively mild, doctors fear new flu strains because of their lethal history. In 1918, a new flu strain killed more than 20 million people.

All three of the Iowa children had mild illness, the CDC reports. The virus also seems treatable with standard anti-viral drugs, Schaffner notes. The 10 cases of H3N2 in 2011 also have been spread throughout the USA -- in Pennsylvania, Maine, Indiana and Iowa -- which doesn't indicate a disease "cluster" or outbreak, Schaffner says.

In a report released late Wednesday night, the CDC noted that, as part of "routine preparedness," it has already produced a "candidate vaccine virus" that could be used against this new strain, and has given it to vaccine makers.