Pfizer Inc said on Friday the COVID-19 pandemic could extend through next year and announced plans to develop a three-dose vaccine regimen for children ages 2 to 16, a move that could delay its authorization.

The U.S. pharmaceutical company made its comments as European countries geared up for further travel and social restrictions and a study warned that the rapidly spreading Omicron coronavirus variant was five times more likely to reinfect people than its predecessor, Delta.

Pfizer executives said the company believed that by 2024, the disease should be endemic around the globe, meaning it would no longer be a pandemic. The company projected that “COVID will transition to an endemic state potentially by 2024.”

Prior to the Omicron variant, top U.S. disease doctor Anthony Fauci forecast the pandemic would end in 2022 in the United States.

Announcing plans to develop a three-dose regimen for ages 2 to 16, Chief Scientific Officer Mikael Dolsten told a conference call that results of three doses among people older than 16 showed that approach offered greater protection.

“Therefore, we have decided to modify each of the pediatric studies to incorporate a third dose to the series and seek licensure for a three-dose series rather than a two-dose series as originally anticipated,” the company said.

Pfizer developed its COVID-19 vaccine with Germany`s BioNTech SE. The companies have been developing a version of their vaccine tailored to combat the Omicron variant, but have not decided whether it will be needed. They expect to start a clinical trial for the updated vaccine in January, the Pfizer executives said.

The risk of reinfection with the Omicron variant is 5.4 times higher and it shows no sign of being milder than the Delta variant, a study by Imperial College London found, as cases soar across Europe and threaten year-end festivities.

Past infection may offer as little as 19% protection against reinfection by the new variant, Imperial College said, noting that the study of hundreds of thousands of cases, including 1,846 confirmed as Omicron, had not been peer reviewed.

MOVES TOWARDS MORE RESTRICTIONS

The new findings may add urgency to countries` efforts to speed up vaccination booster campaigns to try to diminish the burden on hospitals and health systems. So far, a spike in infections in Britain and elsewhere in Europe has not led to a big jump in hospitalizations or deaths.

Uncertainty about the impact Omicron`s quickfire spread will have on a global economic recovery was reflected in diverging paths taken by major central banks this week.

The Bank of Japan maintained its ultra-loose monetary policy on Friday, although it dialed-back emergency pandemic funding.

Germany, Ireland, Switzerland and Denmark were all moving toward further travel restrictions, following the footsteps of France, which closed its borders this week to most non-resident Britons.

Switzerland will from Monday until Jan. 24 expand the requirement to show proof of vaccination or recovery from the coronavirus in order to access indoor venues like restaurants, while discos and bars will require a negative test result.

With the new variant accounting for a fifth of daily cases, the Danish government proposed closing theatres, cinemas, entertainment parks and conference centres, as well as limiting large crowds in stores and shops just seven days before Christmas Eve.

“In record time, the rules of the game have again been changed,” Prime Minister Mette Frederiksen told reporters. “This is not a complete closure of the society, as we saw last winter. Our aim is still to keep as much of society open as possible.”

Denmark logged almost 3,000 Omicron infections in the 24 hours to Thursday evening – doubling the previous day`s count – while overall daily infections broke another record. Denmark`s parliament must approve the proposed restrictions before they can be implemented.

Ireland`s Deputy Prime Minister Leo Varadkar said that in the face of a “cruel virus,” his government had no choice but to consider unpopular measures including early closing times for bars and restaurants.

Under rules that could be announced later on Friday, travellers to Germany from Britain would be required to quarantine for two weeks, a German Health Ministry spokesperson said.

RISING COVID-19 DEATH TOLL

Since the coronavirus emerged in Wuhan, China almost two years ago, more than 5 million people have died of COVID-19 globally and more than 272 million cases have been reported.

More than 8.5 billion doses of COVID-19 vaccines have been administered worldwide – an effort now complicated by Omicron`s emergence.

The variant has driven infections in Britain close to peak levels seen in early 2021, although hospitalisations and deaths remain much lower. European countries and the United States have also seen infections spike in December.

European Union governments have agreed to order over 180 million doses of the adapted version of the vaccine being developed by BioNTech and Pfizer, the head of the EU executive body, the European Commission, said.