One of President Barack Obama's top economic advisers said the federal stimulus package is helping stabilize the wounded U.S. economy but cautioned that full recovery is still a "tremendous distance" away.

"The bottom line is that we are no doubt in for more turbulent times," Council of Economic Advisers Chairwoman Christina Romer said in remarks prepared for delivery to the Economic Club of Washington. But she added that "the actions we have taken, particularly the American Recovery and Reinvestment Act, have clearly changed the trajectory we are on."

Speaking a day before the government releases new figures for the U.S. labor market, Romer rebuffed critics who complain that the 26-year high unemployment rate is evidence that the $787 billion Recovery Act has failed to create jobs or goose the economy. She called that argument "just plain silly," comparing the situation with a doctor prescribing an antibiotic to a patient.

"Sometime after you get the prescription, and maybe even after you take the first pill, your fever spikes. Do you decide that the medicine is useless? Do you conclude the antibiotic caused the infection to get worse? Surely not," she said. "You probably conclude that the illness was more serious than you and the doctor thought, and are very glad you saw the doctor and started taking the medicine when you did."

Romer said one estimate of the Recovery Act's effects, which uses gross domestic product and employment data from 1990 to 2007, suggests that employment is about 485,000 jobs above what it would have been in the second quarter without the stimulus. She pointed to analysts' estimates that the stimulus has added between two and three percentage points to real GDP growth in the last quarter.

The unemployment rate is expected to have risen again in July and Romer repeated the administration's view that growth in jobs will lag the anticipated economic recovery. She said that recovery could begin in the second half of the year, pointing to private-sector forecasts based on recent data.

But she warned that the economy, which contracted 1% in the second quarter, remains "far from healthy," creating uncertainty around the strength of any turnaround.

"The strength will depend on a range of factors, including how fast the economies of our trading partners recover; whether American consumers decide to increase their savings rate even more than they already have; and how quickly financial markets and business confidence return to normal levels," Romer said.

Over each of the next five quarters, Romer said, the economy will receive around $100 billion in fiscal stimulus, the impact of which will increase because of the multiplier effect.

Answering audience questions after her speech, Romer said she isn't worried about an outbreak of inflation because the economy is "far from overheating" and reiterated that the White House isn't considering raising taxes on the middle class to address the record budget deficit. She said Obama is committed to tackling the country's deteriorating finances through health care reform.

Romer declined to answer a question on the dollar's prospects: "I know more than to speculate on what the dollar's going to do, especially in front of five TV cameras."

She also declined to discuss the administration's plans for Fannie Mae (FNM) and Freddie Mac (FRE), the subject of mounting speculation in Washington.

"Of course, something we're going to be thinking about is where do we go from here," she said, adding that she didn't want "to get ahead of the process," which is just beginning.

-By Henry J. Pulizzi, Dow Jones Newswires; 202-862-9256; henry.pulizzi@dowjones.com