BERLIN (AP) -- A debate over two different swine flu vaccines overshadowed Germany's launch of a public inoculation program against the pandemic on Monday.

Critics warned the vaccinations campaign could be a "million-euro flop" as many people might refuse to participate after learning they would receive a different shot than one being given to politicians, high-ranking government employees and soldiers.

German authorities ordered 50 million doses of swine flu vaccines, and began inoculating physicians, nurses, rescue workers and the chronically ill this week.

However, most Germans will be getting Pandemrix, a vaccine by GlaxoSmithKline PLC that contains an adjuvant, while Germany's politicians, government employees and troops will get Celvapan, made by Baxter International without an adjuvant.

Adjuvants -- or chemical compounds that boost the human body's immune response and stretch the vaccine's active ingredient so more doses can be made - are relatively new in flu vaccines, and there is limited data on how safe they are in certain population groups, such as pregnant women and children. No flu vaccines with adjuvants are licensed in the U.S., though they are commonly used in Europe.

Wolfgang Wesiack, the head of the Association of German Internists, warned of "vaccine fatigue" and said many people feared a "two-class health system."

Government spokesman Ulrich Wilhelm defended the vaccination policy, saying last week the two vaccines were equal.

He also said Chancellor Angela Merkel would get the Pandemrix shot, intended for the general population.

There have been no major side effects reported in any of the ongoing swine flu vaccine trials, including those using adjuvants.

Some countries, such as Canada, have ordered special stocks of non-adjuvanted swine flu shots for pregnant women and children, thought to be most at risk from swine flu. Though the vast majority of swine flu cases are mild, and most people recover without needing treatment.

The World Health Organization recommends countries use vaccines with adjuvants to increase the global supply.

All flu vaccines have the potential to cause side effects, from sore arms and headaches to fever.

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