MONTREAL/WASHINGTON:A global aviation manual now under review by a UN body suggests global guidelines calling for the use of highly reliable tests when screening passengers to detect the novel coronavirus ahead of flights, three sources familiar with the matter said.

Carriers and airports are pushing for uniform global testing guidelines to waive strict quarantine requirements that are decimating travel, with airline trade group IATA forecasting a 66% decline in 2020 air traffic because of the pandemic.

Travel restrictions and the use of testing now vary globally. Certain airlines require passengers to obtain a negative test, even as some countries allow visitors in without quarantine, while others bar all non-essential foreigners.

The International Civil Aviation Organization (ICAO) Manual on Testing and Cross Border Risk Management Measures, expected in November, would offer voluntary technical guidance but not oblige countries to remove quarantines.

The manual is not expected to suggest specific tests, such as antigen or polymerase chain reaction (PCR), the sources said. Instead, it would recommend passengers be screened using a test with a sensitivity and specificity of 95% so there would be few false positives and negatives, the sources added.

Some rapid tests are less sensitive and therefore more likely to miss positive cases than PCR alternatives, although the accuracy gap has narrowed.

One of the sources said a range of tests, with reliability as low as around 80% to close to 100%, had initially been considered.

Another proposal is that passengers be tested up to 48 hours ahead of travel but not necessarily at the airport, the sources said. The sources declined to be identified as the discussions are confidential.

U.S. Federal Aviation Administration (FAA) Deputy Administrator Dan Elwell told Reuters on Wednesday that the manual would not be "heavy handed" or provide a prescription for testing. He did not confirm specific details about the manual.

"It's like 'look, if you are going to do pre-departure testing or arrival testing or quarantine, here’s how we think you should do it,'" said Elwell, who heads an ICAO working group on issues like testing and quarantines.

ICAO said in an emailed statement the manual provides countries with a risk management framework for evaluating testing options and factors to consider, should a country elect to implement testing.

While the United States "would like to get to a point where quarantine is not necessary," Elwell said, it would be difficult to create global guidelines for removing travel restrictions through testing since countries have individual concerns," he said.

"There are a lot of mixed feelings about quarantines."