Observed every December 1, World AIDS Day is a grim reminder that while we’re trying to constrain COVID-19, humanity is still in the midst of multiple pandemics—and one of them has already killed about 33 million people over four decades.

In 2019, according to UNAIDS, an estimated 38 million people were living with HIV globally and “around 690,000 people died from AIDS-related illnesses worldwide.” The encouraging news—as encouraging as such lethal news can be—is that 2019’s mortality marked a 60 percent reduction since 2004, the peak year of AIDS deaths.

But the decline we’ve seen for 15-years may be interrupted, sadly, for the HIV and novel coronavirus (SARS-CoV-2) pandemics are crashing into each other.

I first became concerned about COVID-19’s effect on AIDS when I was in Greece last February doing field research. As COVID began shutting down nearby Italy, my colleagues who did HIV prevention in Athens were trying to figure out how they’d keep testing and treating people if they had to go into lockdown. In the coming months, as Apoorva Mandavilli reported in the New York Times in August, COVID would go on to put an enormous strain on supply chains and needed resources to care for people affected by HIV, tuberculosis and malaria around the world.

Here in the U.S., keeping people susceptible to or living with HIV getting the support they need has become an enormous challenge for colleagues in Illinois, New York and West Virginia. And as Zachary Siegel reported in the New Republic, hard-earned gains addressing the opioid crisis, overdosing and HIV have been lost.

So, do hopeful press releases (not peer-reviewed studies) about potential coronavirus vaccines coming to market soon —some supposedly shipping around the country for potential use in just a matter of days—signal an end to at least one of these pandemics and succor to those it has harmed the most?

Unfortunately, AIDS history suggests not.

There have been effective antiretroviral medications for HIV for almost 25 years now. And yet, a majority of people AIDS has so far killed had yet to die when those drugs first arrived; annual AIDS deaths would continue to go up for another decade, and the better part of a million (mostly nonwhite) people are still dying every year.

Why is this? And what does it tell us about the effect we can expect a vaccine to have on SARS-CoV-2, a virus transmitted far more casually than HIV; which is already in much faster circulation than HIV ever achieved; and which has already killed about a million and a half people worldwide? (For comparison, HIV didn’t kill that many people in any given year until it had been around for almost two decades.)

It’s important to note there is no vaccine for HIV as such. However, the antiretroviral therapy (ART) taken by people who are living with HIV and the drugs that people who are HIV-negative can take as a form of pre-exposure prophylaxis (PrEP) do share a significant property with vaccines: they curb onward transmission. When someone living with HIV is able to access and adhere to ART, it not only saves their life; it makes their viral load undetectable and untransmittable to other people. Similarly, in stopping HIV from taking hold in their bodies, PrEP stops internal and onward transmission. This drives viral rates down within social networks, creating something akin to herd immunity. When HIV keeps encountering ARTs within communities, it has nowhere to go and cycles itself out of existence.

Similarly, a vaccination for measles or influenza (or potentially for COVID-19) not only keeps the vaccinated person safe from infection, but keeps them from transmitting the pathogen, creating group protection within their social spheres. And when a virus has nowhere to go, herd immunity is achieved.

Unfortunately, the inverse is also true. When a viral rate goes down within a pharmacologically protected population, then absent an antiracist, anticapitalist medical intervention, we can expect existing disparities of race and class to get worse and for viral rates to go up within populations that don’t get new drugs. As I discuss in my forthcoming book, the racial disparities of AIDS were not equalized with the advent of ARTS; they have worsened.

Similarly, absent an anticapitalist, antiracist rollout of any potential coronavirus vaccine, we should expect coronavirus rates to pool within already marginalized populations—as HIV has already concentrated amongst Black people in the U.S.

While HIV and SARS-CoV-2 are very different viruses with distinctive modes of transmission and progression, they both disparately impact a similar population that I call the viral underclass. AIDS and COVID-19 impact similar populations that share certain social determinants of their health, particularly in regards to being unhoused. For instances, Black Americans (who are only about 13 percent of the population) are somewhere between half and two thirds of people who are forced to be unhoused in the U.S. Being without a home criminalizes them and makes them more susceptible to poverty, incarceration, sexual abuse, lack of health care access, being locked out the formal economy and various co-morbidities that increase their risk for HIV and AIDS. Being unhoused also makes accessing or adhering ARTs difficult if not impossible.

Similarly, in “Pandemic Housing Policy: Examining the Relationship Among Eviction, Housing Instability, Health Inequity, and COVID-19 Transmission, (Journal of Urban Health, forthcoming) author Emily Benfer and her co-authors David Vlahov, Marissa Long, Evan Walker-Wells, J.L. Pottenger, Gregg Gonsalves and Danya Keene explain how our vile eviction crisis is fueling COVID transmission and death. In “2016, the last available year of nationwide eviction data, 3.7 million evictions were filed nationally,” they write, which disproportionately affected “Black and Hispanic renters.”

And given the loss of millions of units of affordable housing over the past decade, things have only gotten more dangerous for how that will affect COVID transmission. As Benfer, et al., write, “Eviction immediately leads to overcrowding, doubling up, homelessness, and housing instability.” This doesn’t always lead to living on the street but to “‘couch surfing,’ residing in shelters, sleeping in cars or outdoors,and doubling up with friends and family who may themselves be at risk for COVID-19. Given that the people they bunk up with “often work in occupations with higher risk of exposure,” everyone’s likelihood of exposure increases. (The legal record created by eviction makes accessing housing and employment more precarious in the future, too.)

“Eviction may also lead to lower access to COVID-19 testing and medical attention by driving families to poorer, under resourced neighborhoods and medically underserved geographic areas with fewer medical facilities and providers, in addition to decreased care affordability,” they also write. This is going to be particularly disastrous if a coronavirus vaccination requires multiple doses spread over weeks. (For people living with HIV, steady housing is a similar requirement for pharmacological adherence.) How will people in a home one week but in a shelter, car, friend’s living room or on the street the next, get the necessary dosage?  

The numbers Benfer and her coauthors present are damning: “Lifting moratoriums” on evictions, their literature review found, “translated to a total of 433,700 excess cases” of COVID-19 and “10,700 excess deaths between March 1 and September 3, 2020.”

On World AIDS Day, we would do well to take stock of the ongoing pandemic of AIDS, and to learn from its ongoing and unnecessary horrors that if we created a world without AIDS, we’d also create a world where the COVID-19 pandemic could end as well.