WASHINGTON, Aug. 31 (Xinhua) -- The credibility of two leading U.S. health agencies has been questioned after they made controversial coronavirus-related decisions under possible political pressure, according to a report by the Associated Press (AP).

Stephen Hahn, head of the Food and Drug Administration (FDA), overstated the therapeutic effect of a plasma therapy for COVID-19 authorized by his agency, drawing criticism from scientists, who argue that it was an exaggeration of the benefits, said the report on Saturday.

Meanwhile, the Centers for Disease Control and Prevention (CDC) quietly revised its guidelines, suggesting that fewer Americans need to get tested for the virus, the report said.

"I do worry about the credibility of the FDA and CDC, especially at a time when the capacity of the federal government to advance public health should be a priority for all policymakers," Daniel Levinson, former inspector general of the Department of Health and Human Services, was quoted by the AP as saying.

Trump administration officials said on Wednesday that the White House virus task force revised CDC's testing guidance to "reflect current evidence" without giving further details, the report said.

According to CDC's new guidance, people who have been in close contact with COVID-19 patients do not have to get tested if they do not feel sick.

It obviously breaches the scientific consensus that large-scale testing is needed to curb the pandemic, the report added.