- MIT researcher Dr. Arnold Barnett said the risk of infection on aircraft is likely higher now than it was in the pandemic.
- The infectivity and immunity evasion of the BA.5 variant poses even more risk when travelling.
- While there is no longer a federal mask mandate on airplanes, experts say wearing a mask can provide protection.
In January 2021, passengers on a full 2-hour flight had a one in 1,000 chance of contracting COVID-19, a study published July 2 in Health Care Management Science suggests.
Researchers at MIT used COVID-19 infection rates from June 2020 to February 2021, along with data on the spread of the virus in the air, to model the risk of contracting COVID-19 at different passenger capacities during the study period. The study suggests that from around December 2020 to January 2021, passengers were most at risk of contracting COVID-19 while flying.
Co-author of the study, Dr. Arnold Barnett, an MIT professor who specializes in aviation safety, told Insider that the infection risk on U.S. planes is likely “significantly higher” now, due to a lack of mask mandates on planes and fuller flights.
Proximity to seats matters, studies show
The Omicron subvariant BA.5 is the dominant COVID strain in the US, and many new cases are reinfections, Insider’s Hilary Brueck and Natalie Musumeci previously reported.
People are more likely to contract COVID-19 in enclosed indoor spaces, according to the Centers for Disease Control and Prevention (CDC), especially without proper air filtration or masks. But commercial aircraft, such as the Boeing 737 or Airbus 320 used in this study, are equipped with High Efficiency Particle Air (HEPA) filters, which reduce the risk of transmission, according to a 2020 report from the Harvard School of Public Health. .
A small study, published in November 2020 in Emerging Infectious Diseases, followed 217 passengers on a 10-hour commercial flight, while the mask mandate was still in effect, and found 16 people who tested positive in the days following their arrival. The study suggested that proximity to seats was a large indicator of transmission risk.
The risk of infection is now most likely higher, according to an MIT researcher
MIT researchers found that while the risk of infection dropped to 1 in 6,000 on half-full flights in the summer of 2020, that number rose to 1 in 1,000 by December 2020 and January 2021 on full planes.
Barnett told Insider that because of the contagiousness of the BA.5 variant, the lack of mask mandates on public transportation, and much busier planes than in 2020, he expects the infection risk is now higher than what was found in the study.
The risk is probably even greater on flights longer than two hours, or for passengers on multiple connecting flights, he said.
Barnett said he regularly travels by plane wearing an N95 mask and tries to keep his distance from other travelers when he can.
Experts say you should still wear masks when flying
As of April 2022, the Transportation Security Administration will no longer enforce a federal mask requirement for people traveling on airplanes.
However, both the CDC and other public health experts still recommend wearing a mask on airplanes. Aircraft HEPA filters don’t always work while boarding or alighting and don’t always protect you from exposure, Gigi Gronvall, an epidemiologist and Senior Scholar at the Johns Hopkins Center for Health Security, previously told Insider.