A man carries his empty oxygen tank to be filled after arriving at the head of the line, in the Villa El Salvador neighborhood of Lima, early Thursday morning, Feb. 18, 2021. A crisis over the supply of medical oxygen for coronavirus patients has struck in Africa and Latin America, where warnings went unheeded at the start of the pandemic and doctors say the shortage has led to unnecessary deaths. (AP Photo/Martin Mejia)

Maricar Tajo, 46, who is from the Philippines but moved to Nigeria in 2007 for work, receives oxygen from a private medical service at her house as she recovers from COVID-19 in Lagos, Nigeria Saturday, Feb. 6, 2021. She was resuscitated after falling unconscious in a hospital intensive care unit when her oxygen saturation levels dropped. (AP Photo/Sunday Alamba)

People sleep framed by their empty oxygen cylinders waiting for a shop to open to refill their tanks, in the Villa El Salvador neighborhood of Lima, early Thursday morning, Feb. 18, 2021. A crisis over the supply of medical oxygen for coronavirus patients has struck nations in Africa and Latin America, where warnings went unheeded at the start of the pandemic and doctors say the shortage has led to unnecessary deaths. (AP Photo/Martin Mejia)

Maricar Tajo, 46, who is from the Philippines but moved to Nigeria in 2007 for work, receives oxygen from a private medical service at her house as she recovers from COVID-19 in Lagos, Nigeria Saturday, Feb. 6, 2021. She was resuscitated after falling unconscious in a hospital intensive care unit when her oxygen saturation levels dropped. (AP Photo/Sunday Alamba)

A man sleeps on top of empty oxygen cylinders, waiting for a shop to open to refill his tank, in the Villa El Salvador neighborhood of Lima, Peru, early Thursday morning, Feb. 18, 2021. A crisis over the supply of medical oxygen for coronavirus patients has struck nations in Africa and Latin America, where warnings went unheeded at the start of the pandemic and doctors say the shortage has led to unnecessary deaths. (AP Photo/Martin Mejia)

A worker from a private medical service brings oxygen bottles to aid the recovery of a COVID-19 patient, at her home in Lagos, Nigeria on Saturday, Feb. 6, 2021. A crisis over the supply of medical oxygen for coronavirus patients has struck in Africa and Latin America, where warnings went unheeded at the start of the pandemic and doctors say the shortage has led to unnecessary deaths. (AP Photo/Sunday Alamba)

A doctor tends to a patient on oxygen suffering from COVID-19 in a ward for coronavirus patients at the Martini hospital in Mogadishu, Somalia on Wednesday, Feb. 24, 2021. A crisis over the supply of medical oxygen for coronavirus patients has struck in Africa and Latin America, where warnings went unheeded at the start of the pandemic and doctors say the shortage has led to unnecessary deaths. (AP Photo/Farah Abdi Warsameh)

People lay next to their empty oxygen tanks as many wait for the refill shop to open in Callao, Peru, Monday, Jan. 25, 2021, amid the COVID-19 pandemic. A crisis over the supply of medical oxygen for coronavirus patients has struck nations in Africa and Latin America, where warnings went unheeded at the start of the pandemic and doctors say the shortage has led to unnecessary deaths. (AP Photo/Martin Mejia)

A worker from a private medical service brings oxygen bottles to aid the recovery of a COVID-19 patient, at her home in Lagos, Nigeria on Saturday, Feb. 6, 2021. A crisis over the supply of medical oxygen for coronavirus patients has struck nations in Africa and Latin America, where warnings went unheeded at the start of the pandemic and doctors say the shortage has led to unnecessary deaths. (AP Photo/Sunday Alamba)

A youth rests on his empty oxygen cylinder waiting for a refill shop to open in the San Juan de Lurigancho neighborhood of Lima, Peru, Monday, Feb. 22, 2021. A crisis over the supply of medical oxygen for coronavirus patients has struck in Africa and Latin America, where warnings went unheeded at the start of the pandemic and doctors say the shortage has led to unnecessary deaths. (AP Photo/Martin Mejia)

FILE - In this Feb. 22, 2021, file photo, people sit by their empty oxygen cylinders waiting for a refill shop to open in the San Juan de Lurigancho neighborhood of Lima, Peru. A crisis over the supply of medical oxygen for coronavirus patients has struck in Africa and Latin America, where warnings went unheeded at the start of the pandemic and doctors say the shortage has led to unnecessary deaths. (AP Photo/Martin Mejia, File)

A truck transports bottles of oxygen along a street in Lagos, Nigeria Saturday, Feb. 6, 2021. A crisis over the supply of medical oxygen for coronavirus patients has struck in Africa and Latin America, where warnings went unheeded at the start of the pandemic and doctors say the shortage has led to unnecessary deaths. Doctors in Nigeria anxiously monitor traffic as oxygen deliveries move through gridlocked streets of Lagos. (AP Photo/Lekan Oyekanmi)

Doctors tend to a patient suffering from COVID-19 and receiving oxygen, in a ward for coronavirus patients at the Martini hospital in Mogadishu, Somalia on Wednesday, Feb. 24, 2021. A crisis over the supply of medical oxygen for coronavirus patients has struck in Africa and Latin America, where warnings went unheeded at the start of the pandemic and doctors say the shortage has led to unnecessary deaths. (AP Photo/Farah Abdi Warsameh)