United Airlines announced Thursday that it will offer free coronavirus testing to travelers on select flights between Newark Liberty International in New Jersey and London’s Heathrow Airport beginning next month — part of an effort to boost passenger confidence in air travel at a time when passenger numbers have plummeted.

The four-week pilot program will run Nov. 16 through Dec. 11. All passengers over the age of 2 on select flights between Newark and London will be given free rapid tests. Those who do not wish to be tested will be rebooked on other flights. The goal, United officials said, is to ensure everyone on board has tested negative for the virus.

However, unlike a program that United unveiled earlier this month that allowed certain Hawaii-bound travelers who tested negative for the virus to bypass quarantine requirements, that won’t be the case for those headed to London. Even with proof of a negative coronavirus test, travelers will still be required to follow local quarantine requirements. U.S. citizens can travel to the United Kingdom but must quarantine for 14 days.

Increasingly, the aviation industry sees testing as a key strategy for restarting travel — particularly international travel, which has been hardest hit as countries have closed borders and imposed strict quarantines. According to the most recent update from trade group Airlines for America, international travel was down 77 percent compared with a year ago.

But to do that, the airlines need to convince countries that proof of a negative coronavirus test is a viable alternative to lengthy quarantines. That task is probably more difficult now that the number of infections is growing worldwide.

Still, United officials say such programs are worth trying.

“We believe the ability to provide fast, same-day COVID-19 testing will play a vital role in safely reopening travel around the world and navigating quarantines and travel restrictions, particularly to key international destinations like London,” said Toby Enqvist, chief customer officer for United. “Through this pilot program, we’ll guarantee that essentially everyone on board has tested negative for COVID-19, adding another element to our layered approach to safety. United will continue to lead on testing, while at the same time exploring new solutions that contribute to the safest travel experience possible.”

Passengers will be given the Abbott ID NOW COVID-19, a rapid molecular test that can provide results in about 15 minutes, officials said. The tests will be given on the day of departure and passengers must make appointments in advance. The testing site is located at the Newark United Club near Gate C93. Premise Health will be responsible for administering the test.

The airline already has seen benefits from the testing program it launched for passengers traveling to Hawaii from San Francisco.

Josh Earnest, United’s chief communications officer, said bookings the week the program launched were nearly double that of the previous two weeks.

“What that should tell you and what it tells us, is that there’s a very favorable reaction from our customers to that kind of testing,” Earnest said.

Under United’s agreement with the state of Hawaii, travelers who test negative don’t have to quarantine for 14 days once they arrive in the islands. However, in this instance, travelers — not United — are responsible for paying the cost of the test, which ranges between $80 and $250 depending on the type of test.