As Americans have steadily resumed traveling — and could even ramp up ridership during the holiday season — the novel coronavirus won’t take a back seat.

Rider entries to the D.C. Metro rose by 14 percent from early July to the end of August, while the estimated ridership of New York subways so far in October is more than double what it was for the same time in July. Lyft said rides in August were up by 7.3 percent versus July. For Uber, it isn’t clear if the ride-share app has seen the same resurgence in traffic since the summer that public transit systems have. Uber bookings declined in the second quarter of 2020, according to an earnings call, but the company said its third-quarter report does not come out until next week.

If transit is further spreading the coronavirus, it has not been detected by contact-tracing efforts. Few studies have evaluated public transportation; those that did in Paris, Austria and Tokyo found no evidence that the virus transmitted from traveler to traveler. But across the world, workers and riders continue to test positive. Nearly one-quarter of approximately 3,000 New York City transit employees surveyed had a history of covid-19 infections, according to a New York University pilot study published Oct. 20. Uber and Lyft did not answer questions about how many drivers have tested positive.

Whether you are planning on commuting on the Metro or bus or calling for a car, people who end up riding near each other, possibly for prolonged periods, could still risk transmitting the virus. So what is the best option for getting from Point A to Point B? The Washington Post spoke with an infectious-disease researcher, environmental microbiologist and epidemiologist about which are the safest options and how to reduce the threat of spreading the virus.

All three public-health experts agreed the soundest choice is whatever involves the least contact with others, which would probably be a solo car ride or one where the only other person in the vehicle is the driver. But that does not exclude other considerations: Is there enough ventilation? How much space is there to distance? Are those around you masking up?

Should you wear a mask?

The Centers for Disease Control and Prevention strongly recommended last week that passengers and workers on planes, trains, buses and other public transportation wear face coverings to prevent transmission of the virus — advice that public-health experts have pushed for months, even in public spaces that aren’t necessarily travel-related.

“That’s old information, I hope, to people,” said Krutika Kuppalli, an assistant professor in infectious diseases at the Medical University of South Carolina. “You should be using masks everywhere.”

Ride-share apps Uber and Lyft have required drivers and users to wear masks since May.

While masking guidance — and other recommendations — aren’t necessarily new, compliance is not yet universal. In September, Uber reported more than 1,250 riders in the United States and Canada have lost access to the app for repeated violations of the mask policy.

For public transit systems, rules may vary depending on the city. Metro Transit Authority in New York City said more than 95 percent of travelers are following the statewide mask mandate. The transit agency said Monday that it has distributed nearly 15 million face coverings to workers and travelers. In D.C., Metro told The Post that “anecdotally” the agency has found that “the majority of customers” are obeying the city’s requirement to wear facial coverings in public.

Does disinfecting surfaces matter?

As the coronavirus is most often transmitted via tiny droplets and particles that float in the air, it’s less important to factor in how frequently surfaces are cleaned than how well social distancing and masking is maintained.

Still, public transit systems and ride-share companies have heightened disinfecting protocols during the pandemic. MTA said it disinfects its train cars and buses at least daily and its stations at least two times per day, while Metro said it cleans trains, buses and stations daily. Both Uber and Lyft have distributed cleaning supplies to drivers, the companies said.

No matter if you are on a train or in a car, a rule of thumb after making contact with surfaces: don’t then touch your face, said Erica Marie Hartmann, an environmental microbiologist at Northwestern University. Touching your face might allow the virus to travel into your eyes, mouth and nose.

“You don’t get coronavirus just because it’s on your hands,” Hartmann said. “I wouldn’t be concerned about sitting on seats, I wouldn’t be concerned about touching handrails. The thing you want to be careful about is that after you’ve touched the handrail, don’t rub your eyes.”

Before and after traveling, clean your hands, experts said. Be sure to use water and soap, and scrub for at least 20 seconds.

“Then,” Hartmann said, “you can rub your eyes with abandon.”

What is the difference in air flow?

Depending on the type of public transit — buses or trains — it may be easier to spread out, but cars offer the least amount of space, making cracking a window key to improving ventilation, according to experts.

The HVAC system, as well as the opening and closing doors on New York’s subways, makes Robyn Gershon, a clinical professor of epidemiology at New York University, feel safe about traveling on the subway. Gershon said she has also taken ride-share trips during the pandemic, but she ensures windows are rolled down. Uber and Lyft recommend opening windows if possible.

But that may be more difficult to do so in the winter months, Gershon pointed out.

“At least in New York City, it gets pretty cold,” she said. “That could be a problem.”

Does contact tracing work for transit?

If you do test positive after using public transit or a ride-share app, it’s best to let those you have had contact with know about the infection.

Uber and Lyft offer riders a portal to enter information. The companies said they comply with public-health agencies with their contact-racing efforts and can suspend accounts.

But experts said it may be impossible to ever find out if someone caught the virus on a bus or train that thousands use daily. Gershon said New York City’s contact tracing continues to be “problematic.”

The survey of about 3,000 New York City transit workers, which Gershon led, found no connection between those who tested positive and outbreaks in their Zip codes, implying that the workers may have become infected elsewhere, such as on the job, she said.

“That’s a difficult thing to ever tease out because the virus was so influent in the community here in New York City during the shutdown months,” Gershon said of determining the source of the workers’ infections, “but given their very intense level of contact with the general public, especially early on and with certain jobs, it’s certainly plausible they picked it up from work.”