Air travellers to the United States will face tougher COVID-19 testing rules, while more countries tightened their borders amid uncertainty around the virulence of the Omicron variant and its ability to evade vaccine protection.
Japan and Hong Kong said they would expand travel curbs, Malaysia temporarily banned travellers from countries deemed at risk, while Australia braced for more cases of the coronavirus variant after at least two people visited several locations in its biggest city while likely infectious.
In an attempt to stave off hasty border curbs, the World Health Organization (WHO) urged countries to apply "an evidence-informed and risk-based approach" to travel measures, saying "blanket travel bans will not prevent the international spread, and they place a heavy burden on lives and livelihoods".
Investors remained on edge on Wednesday, even as financial markets came off lows plumbed a day earlier following remarks by the CEO of Moderna that raised questions about the efficacy of COVID-19 vaccines against Omicron.
Global health officials have since offered reassurances and reiterated calls for people to get vaccinated.
"Our best form of defence still remains our vaccines," British Health Secretary Sajid Javid told Sky News.
"It's possible of course, it's possible that it might be less effective. We just don't know for sure yet. But it's also very likely that it will remain effective against serious disease," he said.
Javid said he expected to know more about the variant within two weeks, echoing remarks by other health experts.
European Medicines Agency Executive Director Emer Cooke earlier said that laboratory analyses should indicate over the next couple of weeks whether the blood of vaccinated people has sufficient antibodies to neutralise the new variant.
BioNTech's CEO said the vaccine it makes in a partnership with Pfizer would likely offer strong protection against severe disease from Omicron.
Britain and the United States have both pushed their booster programmes in response to the new variant.
First reported in southern Africa a week ago, Omicron has triggered global alarm, roiled markets, led to travel bans, and highlighted the disparity between massive vaccination pushes in rich nations and sparse inoculation in the developing world.
It has spread to more than a dozen countries, with Nigeria among the latest to report cases of the variant.
Some 56 countries were reportedly implementing travel measures to guard against Omicron as of Nov. 28, the WHO said.
WHO head Tedros Adhanom Ghebreyesus said he's concerned that several member states were "introducing blunt, blanket measures", which "will only worsen inequities".
BORDER CONTROLS
The United States is moving to require that all air travellers entering the country show a negative COVID-19 test performed within one day of departure, the Centers for Disease Control and Prevention (CDC) said late on Tuesday.
Currently, vaccinated international travellers can present a negative result obtained within three days from their point of departure. The new one-day testing requirement would apply to U.S. citizens as well as foreign nationals.
The administration is also considering whether to require travellers to get another test within three to five days after arrival, officials said.
The CDC lists about 80 foreign destinations as having "Level Four", its highest level of COVID-19 transmission, and discourages Americans from travelling to those destinations.
In Asia, Japan, which had already shut its borders to all newly entering foreigners, said it would expand the ban to foreigners with resident status from 10 African countries.
The border closing affecting residents will be in effect from midnight on Wednesday for at least a month.
"We will maintain a sense of urgency and keep track of the situation in various countries to be able to respond quickly and flexibly," chief cabinet secretary Hirokazu Matsuno said.
Hong Kong will expand its entry ban for non-residents to three more countries, Japan, Portugal and Sweden, from Friday.
South Korean Interior and Safety Minister Jeon Hae-cheol called for tighter virus prevention measures to head off Omicron, after suspected cases entered from Nigeria.
The country, which reported a daily record of over 5,000 COVID-19 cases, has not detected any confirmed cases of the Omicron variant so far.
Malaysia has temporarily banned travellers from countries that have reported Omicron cases, and said it will also delay plans to set up vaccinated travel lanes with affected countries.
Global airlines are preparing for fresh volatility, analysts said. Japanese airlines ANA and JAL said they were suspending new reservations for international flights to the country until the end of December.
"It feels a little bit like we are back to where we were a year ago and that's not a great prospect for the industry and beyond," Deidre Fulton, a partner at consultancy MIDAS Aviation, said at an industry webinar.