A man wearing a face mask walks in the rain in London, Britain, on Feb. 3, 2021. The coronavirus variant first detected in Britain has been undergoing a mutation of concern that could help the virus evade the immune system, local media reported. (Xinhua/Han Yan)

A man walks in central London, Britain, on Feb. 3, 2021. The coronavirus variant first detected in Britain has been undergoing a mutation of concern that could help the virus evade the immune system, local media reported. (Xinhua/Han Yan)

A woman wearing a face mask walks in the rain in London, Britain, on Feb. 3, 2021. The coronavirus variant first detected in Britain has been undergoing a mutation of concern that could help the virus evade the immune system, local media reported. (Xinhua/Han Yan)

A woman wearing a face mask walks past a theatre poster in London, Britain, on Feb. 3, 2021. The coronavirus variant first detected in Britain has been undergoing a mutation of concern that could help the virus evade the immune system, local media reported. (Xinhua/Han Yan)

An ambulance drives in central London, Britain, on Feb. 3, 2021. The coronavirus variant first detected in Britain has been undergoing a mutation of concern that could help the virus evade the immune system, local media reported. (Xinhua/Han Yan)

A woman walks in the rain in London, Britain, on Feb. 3, 2021. The coronavirus variant first detected in Britain has been undergoing a mutation of concern that could help the virus evade the immune system, local media reported. (Xinhua/Han Yan)

A woman wearing a face mask walks in central London, Britain, on Feb. 3, 2021. The coronavirus variant first detected in Britain has been undergoing a mutation of concern that could help the virus evade the immune system, local media reported. (Xinhua/Han Yan)

People wearing face masks walk in the rain in London, Britain, on Feb. 3, 2021. The coronavirus variant first detected in Britain has been undergoing a mutation of concern that could help the virus evade the immune system, local media reported. (Xinhua/Han Yan)