Stocks fell and headed for their largest weekly drop in nearly two months on Friday, while safe haven assets such as bonds and the yen rallied as a new virus variant added to swirling concerns about future growth and higher US interest rates.

The variant, detected by scientists in South Africa, may be able to evade immune responses and has prompted Britain to hurriedly introduce travel restrictions on South Africa.

South Africa’s rand fell 1% in early trade, as did US crude futures.

S&P 500 futures fell 0.4%,while the risk-sensitive Australian and New Zealand dollars dropped to three-month lows.

“The trigger was news of this COVID variant… and the uncertainty as to what this means,” said Ray Attrill, head of FX strategy at National Australia Bank in Sydney.

“You shoot first and ask questions later when this sort of news erupts.” Japan’s Nikkei was down 1.7% in early trade and Australian shares fell 0.6%.

MSCI’s broadest index of Asia-Pacific shares outside Japan was down 0.2% for a weekly fall of 1% and world stocks, while still near record highs, headed for a weekly fall of 0.7%, the largest since early October.

Little is known about the new variant.

However scientists told reporters it has “very unusual constellation” of mutations, concerning because they could help it evade the body’s immune response and make it more transmissible.

British authorities think it is the most significant variant to date and worry it could resist vaccines.

Moves in Treasuries were sharp at the open in Tokyo -following the Thanksgiving holiday – as yields quickly pulled back some of the week’s gains.

Benchmark 10-year yields fell 5 basis points to 1.5927%.

The yen jumped about 0.4% to 114.91 per dollar and gold rose 0.2% to $1,792 per ounce.

The moves come against a backdrop of concern about COVID-19 outbreaks driving restrictions on movement and activity in Europe and as markets aggressively price rate rises next year in the United States.