Omicron "a major, imminent threat to public health"

Markets fell on Friday.

The S&P 500 fell 1.0 percent, the STOXX Europe 600 fell 0.6 percent and the Nikkei 225 plunged 1.8 percent.

Worries over the Omicron variant continued to weigh on markets.

A study by Imperial College London showed that the risk of reinfection with the Omicron variant is more than five times higher and it has shown no sign of being milder than Delta.

The study also showed that the effectiveness of vaccines is reduced against the Omicron variant compared to Delta, suggesting that the "level of immune evasion means that Omicron poses a major, imminent threat to public health".