WASHINGTON (NYTIMES) - A heavily criticised recommendation from the US Centres for Disease Control and Prevention (CDC) last month about who should be tested for the coronavirus was not written by CDC scientists and was posted to the agency's website despite their serious objections, according to several people familiar with the matter as well as internal documents obtained by The New York Times.

The guidance said it was not necessary to test people without symptoms of Covid-19 even if they had been exposed to the virus. It came at a time when public health experts were pushing for more testing rather than less, and administration officials told The Times that the document was a CDC product and had been revised with input from the agency's director, Dr Robert Redfield.

But officials told The Times this week that the Department of Health and Human Services did the rewriting itself and then "dropped" it into the CDC's public website, flouting the agency's strict scientific review process.

"That was a doc that came from the top down, from the HHS and the task force," said a federal official with knowledge of the matter, referring to the White House task force on the coronavirus. "That policy does not reflect what many people at the CDC feel should be the policy."

The document contains "elementary errors" - such as referring to "testing for Covid-19", as opposed to testing for the virus that causes it - and recommendations inconsistent with the CDC's stance that mark it to anyone in the know as not having been written by agency scientists, according to a senior CDC scientist who spoke on the condition of anonymity because of a fear of repercussions.

Adm Brett Giroir, the administration's testing coordinator and an assistant secretary at the Department of Health and Human Services, the CDC's parent organisation, said in an interview on Thursday (Sept 17) that the original draft came from the CDC but that he "coordinated editing and input from the scientific and medical members of the task force".

Over a period of a month, he said, the draft went through about 20 versions, with comments from Dr Redfield; top members of the White House task force, Dr Anthony Fauci and Dr Deborah Birx; and Dr Scott Atlas, President Donald Trump's adviser on the coronavirus.

The members also presented the document to Vice-President Mike Pence, who heads the task force, Adm Giroir said.

He said he did not know why the recommendation circumvented the usual CDC scientific review. "I think you have to ask Dr Redfield about that. That certainly was not any direction from me whatsoever," he said.

Dr Redfield could not be reached for comment.

The question of the CDC's independence and effectiveness as the nation's top public health agency has taken on increasing urgency as the nation approaches 200,000 deaths from the coronavirus pandemic and Mr Trump continues to criticise its scientists and disregard their assessments.

A new version of the testing guidance, expected to be posted on Friday, has also not been cleared by the CDC's usual internal review for scientific documents and is being revised by officials at Health and Human Services, according to a federal official who was not authorised to speak to reporters about the matter.

Similarly, a document, arguing for "the importance of reopening schools," was dropped into the CDC website by HHS in July and is sharply out of step with the CDC's usual neutral and scientific tone, the officials said.

The information comes mere days after revelations that political appointees at HHS meddled with the CDC's vaunted weekly reports on scientific research.

"The idea that someone at HHS would write guidelines and have it posted under the CDC banner is absolutely chilling," said Dr Richard Besser, who served as acting director at the Centers for Disease Control in 2009.

Dr Thomas Frieden, director of the agency during the Obama administration, said, "HHS and the White House writing scientifically inaccurate statements such as 'don't test all contacts' on CDC's website is like someone vandalising a national monument with graffiti".

The vast majority of CDC documents are still carefully created and vetted and are valuable to the public, but having politically motivated messages mixed in with public health recommendations undermines the institution, Dr Frieden said.

"The graffiti makes the whole monument look pretty bad," he said.

The current guidelines on testing, posted on Aug 24, said people without symptoms "do not necessarily need a test" even if they have been in close contact with an infected person for more than 15 minutes.

Public health experts roundly criticised the CDC for that stance, saying it would undermine efforts to contain the virus.

"Suggesting that asymptomatic people don't need testing is just a prescription for community spread and further disease and death," said Dr Susan Bailey, president of the American Medical Association, which usually works closely with the CDC Some experts also said the recommendation appeared to be motivated by a political impetus to make the number of confirmed cases look smaller than it is.

Dr Redfield later tried to walk back the recommendation, saying testing "may be considered for all close contacts," but his attempts only added to the confusion. The language on the CDC's website remained unchanged.

The Infectious Diseases Society of America, normally a close partner of the CDC, strongly criticised the recommendation on testing.

"We've communicated that to the CDC and HHS, but I have not seen any signs that they're going to change it," said Amanda Jezek, a senior vice-president at the organisation.

At a congressional hearing on Wednesday, Dr Redfield said the agency was revising the recommendation and would post the revision, "I hope before the end of the week."

The revision was written by a CDC scientist but was being edited Thursday by HHS and the White House coronavirus task force, according to a federal official familiar with the matter.

The CDC has often been criticised during the pandemic for being too slow and cautious in issuing recommendations for dealing with the coronavirus.

That's partly because every document is cleared by at least one individual on multiple relevant teams within the agency to ensure the information is consistent with the "current state of CDC data, as well as other scientific literature," according to a senior agency scientist who spoke on the condition of anonymity.

In all, each document may be cleared by 12 to 20 people within the agency.

"As somebody who reads them regularly and as somebody who has written things with CDC, I can tell you that the clearance process is painful, but it's useful," said Carlos del Rio, an infectious disease expert at Emory University.

"It's very detail oriented and very careful, and they, quite frankly, improve the documents."

At least eight versions of the current testing guidance were circulated within the agency in early August, according to officials. But staff scientists' objections to the document went unheard.

A senior CDC official told the scientists, "We do not have the ability to make substantial edits," according to an e-mail obtained by The Times. The testing guidance was then quietly published on the agency's website.