There have been no serious side effects from the first set of injections of the new swine flu vaccine, federal health officials said Friday in predicting that nearly 200 million doses could be produced by year’s end.

Clinical trials in adults began on Aug. 7, and those in children on Wednesday.

“There are no red flags regarding safety,” said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases, which is overseeing the trials.

Because the only side effects in adults were sore arms, which are typical of any flu shot, trials on children were able to begin, and those in pregnant women are expected to begin early next month, Dr. Fauci said in a telephone news conference with officials from the Food and Drug Administration and the Centers for Disease Control and Prevention.

The vaccine will be tested in about 4,500 people. That is far too few to pick up subtle side effects, but the virus strain in the vaccine is close enough to one strain in seasonal shots so that side effects are expected to be similar.