TRENTON, N.J. (AP) -- Flu vaccine makers have begun shipping their products already, earlier than usual, and for the first time every strain included in the vaccine is new.

The changes are due to a push to vaccinate an extra 30 million Americans -- children ages 5 to 18 -- and to a significant shift in the influenza strains expected to circulate in the northern hemisphere this year. One is a new Australian strain that sickened many last winter, when the vaccine didn't match the prevalent flu strains well.

All but one of the five manufacturers expected to supply a record 143 million doses to the U.S. began shipping the vaccine in the past two weeks. Most say they hope to have all or at least the bulk of their supply in the hands of doctors, clinics and other providers by the end of October.

"We're responding to the desires of health care providers to set up their immunization clinics early," said Donna Cary, spokeswoman for one of the biggest flu vaccine makers, Sanofi Pasteur of Swiftwater, Pa.

In prior years, some manufacturers didn't start shipping until late August or September, and a couple of years ago, problems delayed some shipments until late fall, so many doses were wasted.

Normally, one or two of the three flu strains targeted by annual vaccines stays in the vaccine for several years. Public-health officials make educated guesses on what strains to include, taking into account the strains then circulating in the southern hemisphere. This is the first year all three are new to vaccines for the northern hemisphere.

Two strains, type A viruses called Brisbane 10 and Brisbane 59, were first isolated in Australia last year. The third is a type B virus first seen in Florida in 2006.

One of the Brisbane strains showed up in this country after the 2007-08 flu season began, far too late to be included in vaccines, according to Michael Shaw of the U.S. Centers for Disease Control and Prevention's influenza division.

"That was the one that caused all the problems," Shaw said.

Public-health officials took a black eye over the mismatch, and official later calculated the vaccine was only about 44 percent effective, compared with 50 percent to 90 percent in typical years. That was because neither the vaccine nor natural immunity protected anyone from the new strain, according to CDC.

Over the last flu season, 83 deaths among children were reported; figures for adults are not yet available. While many consider the flu benign, it typically kills about 36,000 Americans, mostly the elderly, and hospitalizes more than 200,000 people every flu season.

This year, the CDC is recommending all children over six months get flu vaccines. Previously, recommendations covered children from six months to 4 years old, plus everyone over age 50, people with chronic health problems, health care workers, caregivers and others in contact with babies or other high-risk people.

With the updated guidelines, CDC now is recommending a total of 258 million Americans, or about 84 percent, get vaccinated.

CDC worries last year's mismatch will discourage some people from bothering to get vaccinated this year. Its annual campaign to encourage vaccination -- run in conjunction with hundreds of partners, from schools and YMCAs to a group of parents who have had children die from the flu -- will start next month and will address the mismatch and stress the new recommendation that youngsters get vaccines.

The agency also is moving back its National Vaccination Week promotion from the week after Thanksgiving to Dec. 8-14 as part of an effort to extend the vaccination season well into the winter, given that flu doesn't peak until February in many years.

Last year, about 129 million doses were produced, also a record.

"There are more manufacturers now, which is helping a lot," the CDC's Shaw noted.

That's a big change since 2004, when there were only two major companies licensed to sell flu vaccine in the U.S.: Sanofi Pasteur, the vaccines division of France's Sanofi-Aventis Group, and Chiron Corp. That year, contamination problems at Chiron's plant in England prevented delivery of about 50 million flu shots, or half the U.S. supply, worrying many patients and doctors and triggering long lines and rationing of shots to protect the elderly and others most vulnerable to flu complications.

Since then, England's GlaxoSmithKline got into the market, getting approval in 2005 for its own vaccine, Fluarix, and then buying the Canadian maker of another vaccine called Flulaval.

"Each year since then we've increased our capacity," said GlaxoSmithKline spokesman Jeff McLaughlin.

Meanwhile, Switzerland's Novartis AG bought out Chiron, and a longtime Australian vaccine manufacturer, CSL Biotherapies, entered the U.S. market.

GSK, CSL and British drugmaker AstraZeneca PLC's subsidiary MedImmune each are making more doses this year. Unlike the others, MedImmune makes a live-virus vaccine inhaled in a mist, rather than injected -- a twist meant to appeal to parents wanting to spare their kids more shots.