Carnival Cruise Line said booking activity nearly doubled pre-pandemic levels on Monday after it announced an ease in COVID-19 testing requirements for passengers, sending its shares more than 3% higher.

The company's parent, Carnival Corp, said on Friday it would drop mandatory testing for guests vaccinated against COVID-19 and allow unvaccinated passengers to travel without an exemption in some cases, after a similar move by rival Norwegian Cruise Line Holdings Ltd.

"Mid-August is typically not a busy month for cruise bookings, but it's clear that pent-up demand for Carnival has not been satisfied and guests are responding very favorably to our updated protocols," Cristine Duffy, president of Carnival Cruise Line, said in a statement on Tuesday.

The cruise industry has bounced back in recent months from an over one-year-long sailing pause caused by COVID-19, but rising inflation and labor shortages pose risks to its outlook.