The first doses are earmarked for health care workers and those most at risk.
The federal government ordered 250 million doses of the H1N1 virus at a cost of $2 billion hoping it will inoculate half of the country.
It's a modest start to what the government expects to be nationwide immunization drive to stop an epidemic.
One of the first Chicago area shipments of the H1N1 vaccine arrived on Monday at Rush Univeristy Medical Center which received 2,000 doses.
"I think you want to protect yourself and you want to protect your family and you want to protect other people in your household," said Dr. John Segreti, Rush University Medical Center.
Stroger Hospital received 3,000; Northwestern received 2,000 doses; and Children's Memorial took in 500.
Those being given top priority include health care workers, children and adults six months to 24 years old, people with chronic conditions and pregnant women.
But the vaccines coming to Chicago are in the form of a nasal spray which is not recommended for pregnant women. They are advised to wait for the injection.
Health officials say the H1N1 vaccine was manufactured in the same way as the seasonal flu shot and is safe.
"All that has changed is the strain that's included in the vaccine. And so we've had many years with a successful, safe seasonal influenza vaccine program so we expect to have the same results with this vaccine," said Dr. Morita, Chicago Dept. of Health.
"They want to know when it is going to be in and if they think their children should be given it if it is safe," said Dr. Irwin Benuck, Chicago pediatrician.
From Indiana to Tennessee to here in Illinois, health care workers are getting the first doses for both professional and personal reasons.
"I'm getting this for my children. I have two girls," said Holly Smith, nurse.
"I take care of high-risk patients whose immune system is weak," said Dr. John Eshun, LeBonheur Children's Medical Center.
Doctors say the nasal spray is just as effective as the injectable form but it works best with people who don't have impaired immune systems. Those not on the priority list should expect to receive the vaccine in mid October. At that time, 40 million doses are expected to be available with more coming every week.
Here's what you need to know:
Q: Why not wait to start until there's enough for everybody instead of the confusing here-and-there vaccinations?
A: Even though Sunday was the official start of flu season, this H1N1 wasn't heeding the calendar -- it's already causing illness in nearly every state. That means getting vaccine to the people at highest risk is a race. So each week, states will distribute however much they have on hand.
Q: If factories are still racing vaccine out the door, how can I be sure it's safe?
A: The Food and Drug Administration clears batches of vaccine before they're released. The H1N1 vaccine is made in the same way as the regular winter flu vaccine that is used with very few, minor side effects by nearly 100 million Americans a year. There's no biological reason the H1N1 vaccine should react any differently, and no red flags have appeared in studies of several thousand people.
"What I want people to know is that no corners have been cut at all," said Dr. Anne Schuchat of the Centers for Disease Control and Prevention.
Q: Why is the nasal-spray vaccine arriving before the shots, and can I use either one?
A: They're considered equally effective, but the maker of the squirt-in-the-nose FluMist was able to finish brewing sooner. There is an important difference, though. Flu shots, made of killed flu virus, are for anyone without an egg allergy. FluMist, besides the egg issue, is only for use in healthy people ages 2 to 49. It's made of live but weakened flu virus. So some people on the first-in-line list for H1N1 vaccine aren't eligible for FluMist.
Q: Who's first in line?
A: Pregnant women; the young, ages 6 months through 24 years; people younger than 64 who have conditions such as asthma or diabetes that increase the risk of complications from flu; health workers and caregivers of newborns.
Q: I thought flu was most dangerous to people 65 and older.
A: Regular winter flu is most dangerous to older adults, but the new H1N1 is predominantly striking the young.
Q: How many shots, or squirts, will I need?
A: Most people will need one dose each of the H1N1 vaccine and the regular winter flu vaccine. But health authorities believe children under 10 will need two doses of the H1N1 vaccine, about three weeks apart. And some very young children getting their first regular flu vaccination will need two doses of it, too, for a total a four inoculations.
Q: Can I get both types of vaccine at the same visit?
A: If you're lucky enough to find a provider who has both at the same time, a jab in each arm is OK, or a jab of one and a squirt of the other. If you opt for the FluMist version of each vaccine, however, you're supposed to wait three to four weeks between squirts.
Q: What if I'm not on the high-risk list and want H1N1 vaccine anyway?
A: Only some will be physically reserved, doses sent to schools or obstetricians, for example. But eventually enough is expected for everyone who wants it within just a few weeks. The government doesn't expect people to be turned away unless that day's supplies run out.
Q: What will it cost?
A: The H1N1 vaccine itself is free because the government bought it with your tax dollars. But providers can charge a small fee for administering it, usually about $20. Regular flu shots tend to cost up to $35.
Q: If H1N1 is the only kind of flu making people sick now, why do I need the regular shot?
A: Health authorities expect regular flu strains to start circulating, too, as it gets colder; seasonal flu typically peaks in January.
On the Net:
Flu information: http://www.flu.gov
The Associated Press contributed to this report.