Global markets swooned Monday as a new coronavirus strain in the United Kingdom sparked renewed travel restrictions in Europe and uncertainty among investors.

Recent days had offered a parade of good news for traders, with the rapid-fire approval and rollout of Pfizer and BioNTech and Moderna’s coronavirus vaccines and the long-awaited deal on Congress’ $900 billion economic relief package. But a fast-spreading variant of the coronavirus in England has thrown another wrench into hopes that normalcy is just around the corner. Fears of the mutation prompted travel bans to the region by European countries and Canada over the weekend, as well as severe lockdown restrictions on millions in London and across southern England.

"The precautions required to assess the potential harm of the new Covid-19 strain will undoubtedly introduce additional risk to markets, which expected a smooth return to normal life following the vaccine’s rollout,” James McDonald, chief executive and chief investment officer of Hercules Investments, said Monday in comments emailed to The Post.

European markets plummeted on the news. The benchmark Stoxx 600 index declined 2.7 percent in midday trading, while France’s CAC 40 and Germany’s DAX both slumped nearly 3 percent. The U.K.’s FTSE 100 index declined 2.5 percent.

Major U.S. indices declined 1 percent or more at the opening bell Monday before recovering some losses. The Dow Jones industrial average ended the day barely positive at 30,215. The S&P 500 index had declined .4 percent to 3,694, while the tech-heavy Nasdaq ticked .1 percent lower to 12,742.

U.K. health officials have said the variant first identified there was spreading 70 percent faster than other strains. The variant has now been found in Australia, Denmark, the Netherlands, Italy and South Africa. But U.S. public health experts and federal officials say that while this strain is fast-spreading, it might not be any more dangerous than others already detected.

There is no evidence yet that the mutation could require changes to coronavirus vaccines, experts say, but investors still are thrown by the prospect of another major setback on the road to recovery. Despite the catastrophic impacts of the pandemic’s first wave, stock markets have hovered near or at record highs for weeks even as U.S. coronavirus deaths have soared past 317,000 and the economy shows signs of slowing.

“We should keep in mind how far we’ve come,” Chris Larkin, managing director of trading at E-Trade, said in comments emailed to The Post. “If the year had ended Friday, [the S&P’s] annual return would have been 14.8% — placing it comfortably in the top half of yearly gains since 1960. Not bad, considering the SPX was down 32% on the year in March.”

The prevailing unease was reflect in oil markets Monday, where the revival of European travel restrictions sparked fears of another broader lockdown. Brent crude, the global oil benchmark sank, 4.1 percent to trade at $50.10 per barrel. West Texas Intermediate crude, the U.S. benchmark, fell 4.2 percent to trade at $47.04 per barrel.

“Crude prices plummeted as a fast-spreading variant of the coronavirus emerging from the UK would cripple all travel across Europe and the US,” Ed Moya, senior market analyst at OANDA, said Monday in comments emailed to The Post. “The short-term crude demand outlook just got dealt a massive blow that will provide added uncertainty over the next couple of months. ”