How many times a day do we hear that coronavirus is "the great leveller", infecting world leaders and bus drivers alike? Should we be finding it reassuring that a deadly virus is the thread that unites our shared humanity across increasingly unequal societies?

This common refrain does not hold up well to scrutiny. While lawyers and bankers work from the safety of their homes, low paid professionals like care home staff, hospital cleaners and delivery drivers continue to work in environments where they are more at risk of contracting the disease.

Self-isolation is not an option for vulnerable communities, such as refugees or the homeless. And some communities are clearly more vulnerable to the disease: In the United States state of Louisiana, for example, 70 percent of the COVID-19 deaths are African Americans, yet the African American community makes up just 33 percent of the population.

As the pandemic takes hold in the southern hemisphere, the supposed equality in the face of COVID-19 will be exposed for the lie it always was.

Intensive care units have buckled under pressure in China, Europe and the US. However, large swaths of the world face a different scenario. Gaza has approximately 20 mechanical ventilators for two million people; the Central African Republic has three ventilators for a country of five million; and Burkina Faso has a grand total of 12 critical care beds for its 20 million citizens.

We can hope that a younger demographic in most of these countries will help mitigate the effect of COVID-19. But many already suffer from tuberculosis, HIV/AIDS, various non-communicable diseases, and infections such as cholera, measles, or malaria. Catching COVID-19 on top of these may prove to be a deadly combination.

For now, the working assumption is that the pattern of severe infection will at least match that seen in Asia and Europe: 80 percent may not require hospitalisation, but some 20 percent will. Most of the latter will need oxygen therapy, and a full quarter of them - mechanical ventilation. For those without such care, death by asphyxiation is all but inevitable.

Oxygen and ventilators will be the dividing line between the north and south, just as access to antiretrovirals drugs (ARVs) were at the beginning of the HIV/AIDS pandemic in the 1990s. For years, Doctors Without Borders (Medecins Sans Frontieres, or MSF) scaled-up ARV treatment projects in South Africa to demonstrate that this divide was neither necessary nor acceptable.

We, and others, refused to accept denying the severity of the crisis, and the fatal indifference towards people who could not afford quality care.

We must refuse to accept the oxygen divide now, too.

COVID-19 moves fast. The virus is highly transmissible and the time between infection and a fatal end is often less than a month. This time we have weeks, not years, to scale up if we want to make a difference.

The unprecedented challenge of COVID-19 for wealthy countries can seem insurmountable in resource-poor settings. Under-resourced health ministries will inevitably bear the brunt.

First, the gulf between the care available and the potential demand is massive. In high-income countries, medical oxygen is taken for granted. It is built into the walls of each hospital room via sophisticated piping systems.

In the hospitals where we work, this is just not the case. Oxygen concentrators demand stable electricity supplies. Or we must source bottled oxygen, which is not a practical solution for a disease where patients require it for days or weeks. In many places, there are simply no supplies of medical-grade oxygen.

Second, very few humanitarian organisations have the knowledge or logistical capacity required to provide high-end medical services, at the best of times. Now we are faced with a new virus that requires highly specialised skills and intubation at scale over several weeks for each patient. Though MSF specialises in medical emergencies and epidemic response, we rarely provide intubation for more than a few hours or days to trauma patients in our warzone hospitals.

Still, MSF plans to provide essential care of critical cases with oxygen therapy, and in a few settings, push our limits to deliver intensive care with mechanical ventilators. We need to challenge this divide, this "socioeconomic triage" where minorities, vulnerable groups, slum dwellers, and in some cases entire populations, will have no access to care and oxygen.

But none of this will be possible unless current obstacles are surmounted. Freedom of movement across borders for medical and humanitarian staff should be facilitated. Bans on exporting medical supplies to particularly vulnerable countries should be lifted. Newly produced medical equipment, drugs and personal protective equipment for front-line workers must be made available beyond national borders.

We must reject policies that abandon half of the world's patients to face the pandemic without access to the oxygen and intensive care available in the North. We need you, reading this text, wherever you are in the world, to denounce policies that expect the south to settle for soap and leaflets telling them to wash their hands. We must all refuse to accept that thousands of those who contract COVID-19 should die - for lack of oxygen.

The views expressed in this article are the author's own and do not necessarily reflect Al Jazeera's editorial stance.