People queue outside of a Costco store in Watford, as the spread of the coronavirus disease (COVID-19) continues, Britain, March 19, 2020. Long queues formed outside a wholesale warehouse in Watford on Thursday as people tried to stock up before measures to tackle the coronavirus threat are possibly tightened further. REUTERS/Paul Childs

People queue outside of a Costco store in Watford, as the spread of the coronavirus disease (COVID-19) continues, Britain, March 19, 2020. Despite the British government and supermarkets saying that there will be sufficient supplies for everyone, many hundreds of people stood in line outside the warehouse close to the north-west of London to buy food and other items. REUTERS/Paul Childs

People queue outside of a Costco store in Watford, as the spread of the coronavirus disease (COVID-19) continues, Britain, March 19, 2020. Long queues formed outside a wholesale warehouse in Watford on Thursday as people tried to stock up before measures to tackle the coronavirus threat are possibly tightened further. REUTERS/Paul Childs

People with their shopping outside of a Costco store in Watford, as the spread of the coronavirus disease (COVID-19) continues, Britain, March 19, 2020. Despite the British government and supermarkets saying that there will be sufficient supplies for everyone, many hundreds of people stood in line outside the warehouse close to the north-west of London to buy food and other items. REUTERS/Paul Childs

People queue outside of a Costco store in Watford, as the spread of the coronavirus disease (COVID-19) continues, Britain, March 19, 2020. Long queues formed outside a wholesale warehouse in Watford on Thursday as people tried to stock up before measures to tackle the coronavirus threat are possibly tightened further. REUTERS/Paul Childs

People queue outside of a Costco store in Watford, as the spread of the coronavirus disease (COVID-19) continues, Britain, March 19, 2020. Despite the British government and supermarkets saying that there will be sufficient supplies for everyone, many hundreds of people stood in line outside the warehouse close to the north-west of London to buy food and other items. REUTERS/Paul Childs