(CNN)While some Americans wait several days or longer for Covid-19 test results, the American Medical Association and other groups want new federal guidelines to help fast-track those who need testing and results urgently.
That would be good news for those suffering symptoms or who were definitely exposed to someone with the coronavirus.
But it could mean longer delays for those seeking test results before going back to work, returning to school, or visiting friends or family.
"As the country continues to struggle to provide laboratories with a consistent supply of reagents, viral transport media, plastics (such as a pipette tips), and other items essential to providing both COVID-19 and non-COVID-19 testing, we recommend that the Administration consider updating testing prioritization guidelines to ensure that the limited testing resources available are directed at those with a medically-indicated need for tests and those identified by well-defined public health surveillance efforts."
The Trump administration's testing czar has said results ideally should be delivered within 24 hours of a coronavirus test. The Department of Health and Human Services did not respond Wednesday to CNN's request for comment on the letter.
Who would get priority testing, and who wouldn't?
The medical groups suggested "those with COVID19 symptoms, those with known exposures to COVID-19, and those in need of pre-procedure testing" should have access to prompt testing and test results.
"As significant surges in new COVID-19 cases create significant demand for new tests, we are also seeing an increase in demand for testing of asymptomatic individuals with no medically indicated need for testing services," the letter said.
"These include tests for employees going back to work, students returning to colleges and universities, and individuals wishing to engage in non-essential travel."
And without improvement in available supplies, "we simply do not have the resources to meet the huge demand for testing by asymptomatic individuals without exposure to COVID-19," the groups wrote.
"We remain hopeful that the United States will soon be able to bolster manufacturing to meet the needs of everyone desiring a COVID-19 test. However, until manufacturing can meet our unprecedented demand for testing services, it is critical that we prioritize our testing resources where they are needed most."
How major delays make some tests 'borderline useless'
"They call that the pre-symptomatic period. So people tend to have more virus at that point seemingly in their nose, in their mouth. This is even before they get sick. And they can be shedding that virus into the environment."
In June, after crowds of young adults were seen reveling without face masks, the White House coronavirus task force coordinator urged all millennials to get tested.
"Thanks to the millennials who have been heeding our guidance, they have been coming forward and getting testing," Dr. Deborah Birx said.
"Whereas before we told them to stay home, now we are telling them to be tested. And this is a great change for us because it allows us now to find the asymptomatic and the mild diseases that we couldn't find before."
But since then, testing capabilities haven't kept up with demand.
In late July, the Trump administration's testing czar said while testing capabilities have improved, "we are not going to stop our efforts until testing is exactly where we want it to be with rapid turnaround times."
At that point, testing becomes "borderline useless," said Dr. Ashish Jha, director of the Harvard Global Health Institute.
If faster testing were universally available, he said in late July, "we could drive this epidemic down, and we could bury it and get very low number of cases."