Amid the spread of the Omicron coronavirus variant, the Biden administration intends to toughen testing requirements for international travelers coming to the US, including both vaccinated and unvaccinated people.

The Centers for Disease Control and Prevention (CDC) announced in a statement on Tuesday that officials are working on a plan that would require international travelers to be tested for Covid-19 within a day before their flight to the US. Currently, fully vaccinated travelers can test for Covid-19 up to three days before their trip.

“CDC is working to modify the current Global Testing Order for travel as we learn more about the Omicron variant; a revised order would shorten the timeline for required testing for all international air travelers to one day before departure to the United States,” said the agency.

Details for the updated testing requirement are still in the works. The new testing protocols will be finalized before Thursday, when Joe Biden will give a speech about the US’s plan to control the Covid-19 spread during the winter months, according to a senior official who added that current details could still change.

The official, who spoke on condition of anonymity because of the shifting scenario, said additional options that were being considered included testing post-travel and even a possible self-quarantine requirement.

The CDC director, Rochelle Walensky, had said on Tuesday: “CDC is evaluating how to make international travel as safe as possible, including pre-departure testing closer to the time of flight and considerations around additional post-arrival testing and self-quarantines.”

Currently, the CDC recommends post-arrival testing three to five days after landing in the US from overseas and for unvaccinated travelers to self-quarantine, but both actions are voluntary with participation believed to be low.

The changes in international travel requirements come just weeks after the US reopened its borders to more international travelers on non-essential journeys, on 8 November, notably for neighbors Canada and Mexico.

With Omicron cases now confirmed in North America, the US president has been working to temper concern, saying in his Thursday remarks: “I’ll be putting forward a detailed strategy outlining how we’re going to fight Covid this winter – not with shutdowns or lockdowns but with more widespread vaccinations, boosters, testing and more.”

When reporters asked if he would consult with other world leaders before making changes in travel requirements, which his predecessor had not done, Biden said: “Unlike Trump I don’t shock our allies.”