Swine Flu Likely to Return to U.S. N...(r in airborne respiratory droplets when ...),Health

"But, if it does go away, it will come back, he added. "I would be pretty sure of that."

A fall/winter resurgence may or may not be more virulent, said Ostrosky.

"We've been very lucky so far that it's appearing to be mild, at least in the U.S., as far as virulence and susceptibility to antivirals is concerned," he said. "It could change. That's one of the concerns."

"The severity depends on whether [and how] the genotype of the virus reassorts itself," Horovitz added. The reassortment may be so minimal as to make no clinical difference, or it could assert itself in entirely new ways."

But a vaccine will likely be ready by the time a second wave hits, Ostrosky noted, and the world is prepared in other ways as well.

"We have completely sequenced the genome of the virus, and it shows low virulence at this point. We know about it. We can prepare," he said. "If nothing else, this has been an extraordinary exercise in preparation."

More information

The U.S. Centers for Disease Control and Prevention has more on the current outbreak of swine flu.

SOURCES: C. Ed Hsu, Ph.D., associate professor, public health informatics, University of Texas School of Health Information Sciences, Houston, and associate director, health informatics, Center for Biosecurity and Public Health Preparedness, University of Texas School of Public Health; John Treanor, M.D., professor, medicine and microbiology and immunology, University of Rochester Medical Center, New York; Luis Z. Ostrosky, M.D., associate professor, medicine and epidemiology, division of infectious diseases, University of Texas Medical School, Houston; Len Horovitz, M.D., pulmonary expert, Lenox Hill Hospital, New York City