Two more O'ahu adults appear to have contracted swine flu, which would bring the number of Hawai'i cases to five.

The federal Centers for Disease Control and Prevention in Atlanta may be able to confirm by as early as tomorrow whether or not the cases are swine flu, also known as H1N1 influenza, state Health Department spokeswoman Janice Okubo said yesterday.

The two adults are under voluntary home confinement and "still have some minor illness," Okubo said. "But they're recovering at home."

Meanwhile, U.S. health officials said they are in good position to quickly produce a vaccine if the flu takes a turn for the worse.

"We have isolated and identified the virus and discussions are under way so that, should we need to manufacture a vaccine, we can work toward that goal very quickly," said Dr. Anne Schuchat, acting deputy director for science and program at the Centers for Disease Control and Prevention.

"At no time in our history have we been more prepared to face this challenge."

Schuchat also noted that the CDC expects to see more people get sick and more serious cases. One factor, she said, is that the Southern Hemisphere is now moving into its flu season.

The CDC has confirmed more than 640 cases of swine flu in the U.S. The CDC and World Health Organization report 42 deaths in Mexico and two in the United States, both in Texas.

Okubo said she did not know if the two new possible cases in Hawai'i are people who recently traveled to Mexico or the Mainland.

The three earlier confirmed cases of swine flu in Hawai'i were all on O'ahu and involved travel to Mainland states with swine flu.

An Army soldier developed swine flu after returning from a trip to Texas. His wife, a civilian, also developed symptoms.

An unrelated school-age child came down with swine flu after traveling to California.

All three have since recovered, Okubo said.

Schuchat of the CDC said this swine flu appears to differ from seasonal flu in that most of the U.S. cases, including those needing hospitalization, involve those age 5 to 50, instead of the very young and the elderly. One possibility is that people older than 50 might have protection because of exposure to similar viruses when they were younger, she said.

After the confirmation of the first three Hawai'i cases, state health director Dr. Chiyome Fukino said earlier this week that more cases are likely.

"It wouldn't surprise us if there are more cases, that is true," Fukino said.

Even before confirmation of the first three cases, people in the Islands began emptying pharmacy shelves of hand sanitizer, masks and anti-viral prescription flu drugs, such as Tamiflu.

As communities around the country deal with the same phenomenon, local pharmacies have been scrambling to restock their supplies to meet the sudden demand.

State health officials, however, are urging healthy people not to seek prescriptions for Tamiflu or stockpile anti-viral flu drugs.

No vaccine has yet been produced for swine flu.