SpaceX launched people to space for the first time in May 2020, a few months after the Covid pandemic began to spread across the United States, and Elon Musk’s company added quarantine precautions to protect NASA’s astronauts in the weeks before launch, according to research recently published in an academic journal.

NASA has had its Flight Crew Health Stabilization program in place for decades, which was initially created during the 1960s Gemini missions and matured during the Apollo missions.

SpaceX’s Demo-2 launch, carrying astronauts Bob Behnken and Doug Hurley, was the first time a private company adapted NASA’s program for a mission. Former NASA administrator Jim Bridenstine explained to CNBC in April 2020 some of the measures the agency and company were taking to protect the astronauts. SpaceX launched the pair to the International Space Station on May 30, 2020, and returned them safely on Aug. 2, 2020.

“The commercial implementation of the NASA Health Stabilization Program by SpaceX with adjustments required during the COVID-19 pandemic was a success, with protocols allowing identification and removal of potentially infectious persons from the program,” the report said.

The report was published in the July edition of the journal of Aerospace Medicine and Human Performance. Authors of the report featured engineers at SpaceX – including Musk himself – as well as representatives at NASA’s Johnson Space Center, Massachusetts General Hospital, and the schools of medicine at Dartmouth, Stanford, the University of Arizona and more.

NASA’s existing program includes a flight crew quarantine beginning 14 days before launch, to limit interaction with others to only those who are known as “primary contacts.” The report said 91 SpaceX employees were entered as primary contacts into the company’s adaptation of NASA’s health stabilization program,

Forty-five days before launch, SpaceX began distributing health screening questionnaires to potential primary contacts. Twenty-eight days before launch, SpaceX began a daily morning survey, with 25 questions to check for symptoms of Covid. The SpaceX flight surgeon received the results of the survey for review each night and followed up with anyone who reported new symptoms. The report said the survey had a 93.4% average daily response rate.

The report noted that 2,720 surveys were completed pre-launch, with 198, or 7.3%, returning with potential symptoms of Covid – with the most common being joint pain, cough, sneezing, abdominal pain, or headache. During the surveying period, 22 employees were contacted by the SpaceX flight surgeon, and five of those employees were reexamined.

“All exams were unremarkable and additional COVID-19 RT-PCR testing was performed on two of the five individuals, who tested negative and returned to duty,” the report said, referring to a reverse transcription polymerase chain reaction test.

Two others were removed from the program “for potential infectious disease,” the report noted, but “both had chronic medical conditions which were difficult to distinguish from infectious disease.”

SpaceX created a “closed-loop system” for interactions with the NASA crew, including flying only by agency or private aircraft, sterilized vehicles, a private entrance to the SpaceX training center, and required face masks and temperature checks. Any SpaceX personnel who would come in “close contact” with the astronauts also completed PCR testing 48 hours before.

The report concluded that SpaceX’s precautions were successful, but noted it could be improved through better “monitoring of areas that were accessible to personnel not under [health stabilization program] protocol.” NASA’s launchpad 39A “was accessed by certain personnel who were not participating” in the program, which created “a potential point of transmission.”

“In addition, further research is needed to adapt [Health Stabilization Program] protocols for pandemic environments when the prevalence of disease in the community is high,” the report noted.