"About half of what we're seeing lately is the novel H1N1 strain," she said.
But health officials still warn that the situation could change quickly, particularly if the virus were to mutate.
"One of the concerns that we have is the virus could change and that it in fact could cause more severe illness," Harper said. "We don't think that's the case right now, but we know that influenza viruses do change frequently."
Worldwide, health officials are identifying more cases. According to World Health Organization statistics released Wednesday morning, 10,243 cases of swine flu have now been identified in 40 countries, and 80 of those infected have died.
Yet prominent infectious disease experts say that even if the WHO raises the pandemic alert from 5 to 6 -- the highest level -- the formal classification is not likely to sway future public health response. Governments and health officials would likely take the same course of action as they are presently, the experts said.
A vaccine for the virus is currently in the works. However, WHO officials have said that drug manufacturers won't be able to start making a vaccine until mid-July at the earliest. They attribute the delay to the fact that the virus does not appear to grow quickly in a laboratory setting, making it difficult for scientists to get a key vaccine ingredient.
While experts search for signs of how deadly the swine flu may become on a global scale, family physicians and emergency medical doctors say patients at home are in the same quandary: how to tell if this flu will pass as usual or turn serious and deadly.
"People who are walking around with a normal-grade fever shouldn't be going to the emergency room for treatment, even though they are," said Dr. Andrew Sama, a member of the American College of Emergency Physician's board of directors.
Sama said the majority of flu cases can be treated at home or with a phone consultation, or a visit to the family doctor.
In the most severe cases, Sama said patients will be shuttled off to the intensive care unit to protect against respiratory failure. He said most people survive, "But generally speaking not everyone who is on a respiratory ICU treatment can be saved."
"Generally speaking, only people who are really ill from the flu -- nonstop vomiting, extremely high fever, inability to eat and drink, excessive weakness, chest pain, severe cough, lethargy, trouble breathing -- should come in," he said.
However, Sama and Dr. Lori Heim, the president-elect of the American Academy of Family Physicians, said three specific groups of people should go to the doctor with much less severe symptoms: children under age 4 with a high fever, people with compromised immune systems and the elderly.
"If you're one of the lucky people in the country who has a regular physician, calling them would be my first choice," Heim said. "But if you can't breathe, don't wait for a phone call back."
ABC News' Rich Esposito and reports from The Associated Press contributed to this report.