Alician Hudson, left, a medical office employee at the Bayer Corp.’s U.S. headquarters in Pittsburgh, receives a flu shot from company physicians assistant Tim Grimes. Businesses will have to wait until high-risk groups have been immunized to get swine flu vaccines for their work force.

Trenton, N.J. ? Plan on getting your swine flu shot at work? Don’t count on it.

Businesses may have to wait months to offer the shot, if they get it at all.

The regular seasonal flu vaccine is available a bit earlier than usual, and federal health officials recommend most people get that shot. Some employees are already lining up for it.

But the strain that’s already a national fixture is swine flu. And for healthy adults, the vaccine will not be readily available.

The first swine flu vaccine should be available in the U.S. sometime around the first week of October.

About 90,000 sites — mainly hospitals, clinics, doctors’ offices, county health departments and pharmacies — are expected to receive doses.

The federal government is covering the cost of the vaccines and related supplies, said Tom Skinner of the Centers for Disease Control and Prevention. At least 195 million doses are expected through winter.

States will get a share based on their population. Their health departments must approve or reject requests from health providers and other groups wanting the vaccine.

From California to Florida, states say they plan to make sure the initial vaccine supply goes to the 159 million people in the priority groups. Their rules vary slightly, but businesses are generally at the back of the line.

Bayer Corp. is providing information on swine flu symptoms and advising workers to consult their doctor about vaccine availability, follow strict hygiene rules and stay home if they get sick and get the seasonal flu vaccine as soon as possible.

Other major corporations, from Exxon Mobil Corp. to Microsoft Corp. and Kroger Co., are taking similar steps. Whether companies will get any swine flu vaccine for their workers is generally unclear.

“We know that our vendor has been approved, and likely will get vaccine,” said Microsoft spokesman Lou Gellos. What remained unclear was whether that company would have enough for all the businesses it serves.

Despite all the uncertainty, about 43 percent of respondents to an ongoing survey by the National Business Group on Health have said they plan to provide swine flu vaccine to employees once the shots are available. Seventy percent said they’ll pay the administration fee, even if workers get shots elsewhere.