COOS BAY — Oregon is preparing for four times as many influenza cases this year, because of the emergence of the new H1N1 strain. That could mean four times as many hospitalizations and four times as many deaths.

All of the flu cases so far this year have been caused by the new strain, said Dr. Mel Kohn, director of Oregon’s Public Health Division.

State health officials have seen evidence that infections on the South Coast may soon peak, but they say Coos and Curry counties aren’t out of the woods yet.

The seasonal influenza strain is expected to hit in December, and a second wave of the H1N1 virus could sweep across Oregon next spring, infecting people who made it through the first round unscathed. People who are infected this fall, or get vaccinated, should be immune.

“Flu is very unpredictable,” he said. “Past experience suggests (a second wave) will be likely.”

In normal flu seasons, between 10 and 20 percent of the population is infected at any one time, he said. There are about 36,000 deaths in the United States, 450 of which occur in Oregon. Complications from the flu cause the deaths, Kohn said. And if the state sees four times as many cases, it’s likely there will be four times as many hospitalizations and deaths.

“I’m not saying we will have four times the number of deaths and hospitalizations,” he said. But, “it’s prudent to prepare.”

The new strain has targeted a younger population than the seasonal flu, Kohn said. State health statistics show that more than 50 percent of the Oregonians hospitalized since Sept. 1 have been between the ages of 5 and 49. Oregonians older than 65, who commonly suffer from flu-like complications, have only accounted for 11 percent.

Pregnant women have been particularly at risk from the new strain.

They have mortality rates six times as high with H1N1 as they do with the normal flu, said Anita Merritt, a certified nurse midwife at Bay Area Hospital. She isn’t sure why. Doctors also have been prescribing Tamiflu to women who have become pregnant.

“The increase in cases is unlike anything in recent years,” she said. “I can’t remember pregnant women on Tamiflu.”

That has been a cause of concern at Bay Area Hospital, where officials have imposed restrictions on visitors to the labor and delivery ward.

The only people 18 and younger allowed into the ward are newborns’ siblings. Hospital officials also are keeping out anyone who has been sick or has flu-like symptoms, said Lonny Anderson, the hospital’s emergency operations planner.

The hospital also wants to avoid large scale worker absentee rates due to sickness. Employees who get sick can only return to the hospital after they go 48 hours without a fever or cough, said Sannie Warbis, director of inpatient services.

But even those restrictions haven’t kept a good number of employees out of the office recently.

“We’ve had more sick calls than usual and they’ve stayed out longer than usual,” she said.

So far, the hospital has been able to limit the spread of the disease inside the facility, though there has been a sizable jump in the number of patients with flu-like symptoms in the past few weeks.

“I don’t think we’ve seen the worst of it,” Anderson said.

President Obama declared a national emergency over the weekend, which is more a precautionary measure, Kohn said. If hospitals need to establish off-site treatments centers to care for patients with flu, the declaration will make it easier to get federal help, he said.

“We’ve been very busy trying to coordinate all this,” he said. “We are going to get through this.”