tl;dr: I have found plenty of references to unusually long lines, and a complete absence of "social distancing" in these lines. O'Hare Intl. Airport's Twitter account and The Washington Post explicitly claim that the medical screening is to blame for the wait times, while others imply it. Until there's a retraction or update to those stories, that makes the claim likely to be true.
O'Hare Intl. Airport on Twitter:
Attention travelers: customs processing is taking longer than usual inside the Federal Inspection Services (FIS) facility owing to enhanced #COVID19 screening for passengers arriving from Europe. Twitter
CNN about airports in Dallas, Chicago and New York:
As Americans are being urged to keep their distance from one another,
travelers returning on flights from Europe say they are being made to
wait for hours in close quarters at US airports to get screened for
coronavirus. When they arrived at airports in Dallas, Chicago and New
York, they faced long lines and confusion, several travelers told CNN.
Karen Rogers, a passenger returning from Paris by way of London,
had been waiting in line for at least five hours to be screened at
Chicago's O'Hare International Airport and was told she would have at
least another hour to go, she said Saturday night. [...]
first wait in line to have their passports checked and to turn in a
declaration form and medical forms for those returning from Europe,
South Korea, Iran and China, Schmidt said.
Then they are taken to a separate line to undergo a screening and
temperature check. [...] - CNN March 15 2020
Washington Post about O’Hare and "other U.S. airports":
Scores of anxious passengers said they encountered jam-packed
terminals, long lines and hours of delays as they waited to be
questioned by health authorities at some of the busiest travel hubs in
the United States.
The administration announced the “enhanced entry screenings” Friday as
part of a suite of travel restrictions and other strategies aimed at
slowing the spread of the coronavirus. Passengers on flights from more
than two dozen countries in Europe are being routed through 13 U.S.
airports, where workers are checking their medical histories,
examining them for symptoms and instructing them to self-quarantine.
But shortly after taking effect, the measures designed to prevent new
infections in the United States created the exact conditions that
facilitate the spread of the highly contagious virus, with throngs of
people standing shoulder to shoulder in bottlenecks. - Washington
Post March 15 2020
CBS about O'Hare:
As weary travelers returned to the U.S. amid coronavirus-related
travel restrictions, they were greeted with packed, hourslong waits
for required medical screenings at airports.
Posts on social media indicated passengers at Chicago's O'Hare
International Airport waited upward of four hours in winding lines - CBS March 15 2020
New York Post about JFK, Newark:
Americans returning from Europe found themselves in a crowded hell of
delays and long lines Saturday night at the 13 airports selected to
handle their incoming flights under new rules enacted by the Trump
administration to combat the spread of the coronavirus. - New York
Post March 15 2020
Bloomberg about O'Hare:
Chicago’s O’Hare International Airport was among those overwhelmed
Saturday with passengers, including many returning from Europe, who
faced new screening measures hastily announced earlier last week.
The crowds of anxious travelers were a stark contrast to the
increasingly loud calls for people to practice “social distancing” as
a way to get ahead of the spread of the coronavirus and buy fragile
health care systems time. - Bloomberg March 15 2020
USA Today about "major airports":
U.S. travelers flying back from Europe were greeted with snaking lines
and hours-long waits at major airports as expanded coronavirus
screenings required by the government's new European travel
restrictions took effect. - USA Today March 15 2020