Centers for Disease Control and Prevention (CDC) Director Rochelle Walensky said the agency had halved its recommended quarantine time based on what the public would “tolerate.” It had also been under pressure from airlines.

Released on Monday, the new guidelines recommend that people testing positive for Covid-19 isolate for five days instead of the 10 previously suggested. Once a person’s symptoms are resolving, they are not asked to test negative to leave isolation, but should wear a mask for another five days.

The new guidelines “really had a lot to do with what we thought people would be able to tolerate,” Walensky told CNN on Wednesday.

“We have seen relatively low rates of isolation for all of this pandemic,” she explained, adding that “some science has demonstrated less than a third of people are isolating when they need to,” so the new advice had to be something “that people were willing to adhere to.”

Amid the spread of the highly transmissible Omicron variant of the coronavirus, cases of Covid-19 have exploded in the US, with a record 431,000 new cases having been recorded on Wednesday, according to CDC data. However, many of these cases are mild or asymptomatic, and Walensky told CNN that those with mild or no symptoms “would not necessarily tolerate being home, and they may not comply with being home.”

A week before the CDC announced its new guidelines, Delta Air Lines wrote to Walensky to ask for the recommended quarantine time to be reduced to five days. Arguing that Omicron was a more benign strain of the coronavirus, and adding that 90% of its workforce was fully vaccinated, Delta said that a continuation of the 10-day isolation guidelines would “exacerbate shortages and create significant disruptions,” as staff who might be well enough to work would be obliged to stay home.

Staffing shortages ended up causing thousands of delays and cancelations over the holiday weekend and into this week, with multiple US and international airlines having been affected. In the days after Delta’s approach to Walensky, other airlines joined in the call for a five-day isolation period, echoing the concerns about shortages and disruptions.

Though the CDC insisted the changes came about due to scientific research having shown that people with Covid-19 were most likely to spread it in the first few days after showing symptoms, the agency was still accused of having caved into pressure from the airline industry.

“We said we wanted to hear from medical professionals on the best guidance for quarantine, not from corporate America advocating for a shortened period due to staffing shortages,” read a statement from the Association of Flight Attendants-CWA on Tuesday.