President Trump and first lady Melania Trump have tested positive for the coronavirus after a busy week on the campaign trail, although it currently remains unknown how the two contracted the virus.

What is known, however, is that President Trump, in the last week of September, crisscrossed the country for campaign rallies (like Wednesday's rally at Duluth International Airport in Minnesota) on Air Force One.

And with the coronavirus pandemic still afflicting the nation, and the demand for air travel very slowly increasing, the public should remember to remain aware and vigilant when flying. But what exactly are the risks of transmission on airplanes?

The CDC confirms that flying can increase the risk of being infected with COVID-19, given close proximity to others in cabin quarters.

The CDC confirms that flying can increase the risk of being infected with COVID-19, given close proximity to others in cabin quarters. (iStock)

The Centers for Disease Control and Prevention (CDC) confirms that flying can increase the risk of being infected with COVID-19, given close proximity to others in cabin quarters.

“Most viruses and other germs do not spread easily on flights because of how air circulates and is filtered on airplane,” the CDC reports on a travel FAQ page. “However, social distancing is difficult on crowded flights, and you may have to sit near others (within 6 feet), sometimes for hours. This may increase your risk for exposure to the virus that causes COVID-19.”

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For the general public traveling via commercial airlines, flying also requires spending time in airports and in security lines, which can also bring one into contact with others and high touch-surfaces.

Still, German researchers suggested in a recent study that the odds of catching the viral disease on a plane with infected passengers aboard appear to be relatively small, though still possible.

Dr. Aaron Glatt, chief of Infectious Diseases of Mount Sinai in New York, told Fox News the report from the Institute for Medical Virology at Goethe University in Frankfurt is consistent with other research findings.

For the general public traveling via commercial airlines, flying also requires spending time in airports and in security lines before boarding.

For the general public traveling via commercial airlines, flying also requires spending time in airports and in security lines before boarding. (iStock)

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“Airplane trips, especially if they are of a longer duration, have the potential to transmit infection from an infected person to the people sitting in their immediate vicinity," Glatt said.

“The good news, however, is that even with no attempts to prevent spread, [the] spread was limited to only those in close proximity. Plus, nowadays with a better understanding of viral transmission, and recognizing the importance of masking and social distancing as possible, the likelihood of transmitting COVID-19 to someone on an airplane is very low," the epidemiologist added.

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If one must travel, the CDC recommends wearing a mask that covers one’s mouth and nose, staying at least 6 feet away from others and washing hands often, or using a hand sanitizer with at least 60% alcohol. Travelers should also avoid touching their eyes, nose and mouth and stay away from anyone who is sick.

It remains unclear where the Trumps may have caught the coronavirus.

The president confirmed early on Friday morning that he and the first lady have tested positive for COVID-19 and will be quarantining at the White House until they recover.

Fox News' Amy McGorry and Brie Stimson contributed to this report.