San Joaquin County’s top public health official expects this year’s flu season to be about twice as bad as usual, and plans are under way to tamp down the number of people who come down with the swine flu.

To gauge how widespread the swine flu might be this winter, look to the Southern Hemisphere, which is at the height of its flu season, experts say, and where the number of flu cases is about double the annual norm.

More than 354,000 cases of swine flu have been confirmed worldwide, according to Flutracker.com, a number that county health officer Karen Furst says is likely tiny compared to what the actual number is, because most cases go untested. Furst said the number of cases could be “20 or 30” times that amount worldwide. Of those, there have been 2,270 deaths officially reported.

That’s a far cry from when the virus appeared in the spring, inspiring fear that it might duplicate the 1918 influenza pandemic that killed roughly 18 million people around the globe, when half the people infected with the virus died from it.

In 1918, sporting events and other large public gatherings were banned in the U.S. at the height of the virus’ deadly spread. The power to shut down such events locally rests with health officer Furst, but she expects not to use it.

Now that health officials have a better handle on how the virus behaves and that it’s not as dangerous as it first appeared to be, an effort will be made to keep schools open and keep sick kids home, rather than closing schools as was briefly done earlier this year.

Furst said it’s possible a school will be ordered closed, though, depending on how many students come down with the swine flu.

Health officials urge anyone who displays flu-like symptoms to stay home from work or school until they’re no longer infectious. And, of course, people should not cough or sneeze into the air, and washing hands is important to prevent the virus from spreading.

Though the swine flu this season is not expected to be anywhere near as lethal as the 1918 bird flu, and probably not as deadly as seasonal flu (which kills about 60,000 people annually in the U.S.), it is a previously unseen virus that threatens an unusual segment of the population — hitting young people and pregnant woman more than seniors.

“It’s a very, very different pattern than regular influenza,” Furst said.

Like the seasonal flu, public health officials will try to retard the spread of the swine flu with a vaccine that’s now being tested. Only in this case, officials will target kids and young adults for the swine flu vaccine, which could be distributed by October.

Unlike the seasonal flu vaccine that’s given to nursing homes and other places where seniors are, Furst’s office will work closely with schools and pediatric doctors to distribute the vaccine.

The Centers for Disease Control and Prevention recommends children 6 months and older and adults up to age 19 be vaccinated annually against the swine flu.

Schools, Furst said, are going to be a “very important partner in getting the vaccine out.”

Coordinating how vaccines are handed out might be the biggest job the public health department has as it works to prevent the effects of swine flu before an outbreak is in full bloom.

Vaccines will be given on a voluntary basis, and it’s possible people will have to take more than one dose before they’re immunized against the swine flu, Furst said. She added that the swine flu shots will not protect against the seasonal flu.

Outside of prevention, a strategic stockpile of anti-viral drugs such as Tamiflu will be made available in case it’s needed to quell a swine flu epidemic, Furst said.

To track how many people have the virus, the public health department will work with hospitals, clinics and schools to tally the number of students absent because of the flu.

At Sutter Tracy Community Hospital, extra masks and other supplies have already been ordered in case of an epidemic, said spokeswoman Karen Mudd. And should the virus take a turn for the worse, the hospital has a plan in place, following the CDC’s recommendation of who should get vaccinated first in the event of a shortage — pregnant woman, caregivers to those younger than 6 months old, health care and emergency workers.

The hospital has already started sharing information with others in the Sutter corporate chain so doctors can track the virus.

Unlike in the spring, when just about any suspected case of swine flu virus was tested, overwhelming labs, tests for swine flu will be mostly reserved for those hospitalized with the swine flu and people who die from flu symptoms.

Public health officials are also trying to educate the public about the risks of the swine flu, how to take care of someone who is sick, and the importance of hand-washing. To that end, Furst’s office in September will host a “summit” with people in business, nonprofit groups, school officials and other public administrators.

“We want to make sure everyone has good information,” said public health spokeswoman Shene Bowie. “Our goal is to get out as much information as possible.”