Worldwide, health officials are identifying more cases. According to WHO statistics released Tuesday morning, 9,830 cases of swine flu have now been identified in 40 countries, and 79 of those infected have died.
Yet prominent infectious disease experts say that even if the WHO does raise the pandemic alert to 6 -- the highest level -- the formal classification is not likely to sway future public health response.
"Pandemic level is another disservice; it reflects only the degree of spread of a bug and nothing else," Dr. Frank James of the School of Public Health and Community Medicine at the University of Washington, Seattle told ABC News. "If a team of experts went out looking for the bug widely they could find it now in enough areas to qualify this as a Level 6."
Dr. William Schaffner, chairman of the Department of Preventive Medicine at Vanderbilt Medical School, also wondered what a "Level 6" definition would mean for people affected.
"I continue to wonder whether this is useful, given the general level of severity of the illness," he said. "Recall that these levels relate only to geographic distribution of the illness, not severity."
To further complicate the matter, severity of the flu is not the only important signal to those fighting infectious disease. If it is too lethal, the flu might defeat itself by killing its victims before there's time for the virus to spread.
"One of the better determinants is the incubation period," said Robert I. Fields, chair of the department of health policy and public health at the University of the Sciences in Philadelphia.
Fields said a long incubation period with mild to no symptoms would allow the virus to spread quickly and widely before people quarantine themselves. Couple a long incubation period with a particularly deadly strain, and doctors have their "worst nightmare" of a flu virus, Fields said.
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 from 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 -- non-stop 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.