Pandemics do not arrive politely.
They do not wait for healthcare systems to prepare, for politicians to agree, or for science to catch up.
They expose weaknesses.
They expose assumptions.
And, perhaps most importantly, they expose the difference between what medicine believes it knows and what it can actually prove.
The HIV/AIDS pandemic and the COVID-19 pandemic emerged around forty years apart.
Both began with uncertainty.
Both caused fear.
Both killed millions.
Both generated stigma, misinformation and political argument.
Yet medically they occurred in completely different worlds.
When AIDS emerged in 1981, clinicians had very little to offer beyond treatment of the infections and malignancies appearing as patients’ immune systems collapsed.
When COVID-19 appeared at the end of 2019, the virus was identified and sequenced rapidly, diagnostic tests followed, large clinical trials were organised within months and vaccines were being administered within roughly a year.
That raises an uncomfortable but fascinating question:
Would we have responded to COVID-19 anywhere near as quickly had HIV/AIDS never happened?
We can never prove the answer.
But there is a compelling argument that the scientific response would have been considerably slower.
COVID did not arrive in a scientific vacuum.
It arrived after forty years in which HIV/AIDS had forced medicine to learn how to fight a previously untreatable viral disease.
In many respects, COVID was not answered in twelve months.
It was answered with forty years of accumulated pandemic science.
For me, this is also more than an academic comparison.
I survived severe COVID-19 requiring intensive care, complicated by COVID-associated encephalitis.
I was not diabetic when I entered hospital.
During treatment with dexamethasone my blood glucose rose to approximately 32 mmol/L and I was treated with metformin.
I was subsequently sent for an MRI.
When asked whether I was diabetic, I answered no.
That was not a lie.
I had never previously been diabetic.
Contrast was administered.
I subsequently developed an acute kidney injury and remained in hospital for roughly another two weeks.
That experience taught me something very simple:
critical illness is rarely one disease, one treatment and one outcome.
Treatment changes the patient.
The disease changes the patient.
The complications change the patient.
And sometimes the patient’s clinical state changes faster than the labels attached to them.
AIDS: When Medicine Could Treat the Consequences but Not the Cause
When AIDS was first recognised, clinicians began seeing young people with diseases that simply should not have been occurring with such frequency.
Pneumocystis pneumonia.
Kaposi sarcoma.
Tuberculosis.
Fungal infections.
Other opportunistic infections.
The common thread was profound immune failure.
Initially doctors could treat those individual conditions.
They could treat the pneumonia.
They could treat the fungal infection.
They could sometimes treat the malignancy.
But they could not stop the underlying destruction of the immune system.
The first major antiviral breakthrough came with zidovudine — AZT — approved in 1987.
It proved that HIV replication could be attacked pharmacologically.
But early treatment had limitations.
Toxicity was significant.
Resistance developed.
One drug was simply not enough.
The major transformation came during the mid-1990s with combination antiretroviral therapy.
By attacking HIV at several points in its replication cycle, treatment could suppress the virus much more effectively.
By around 1996, HIV medicine had fundamentally changed.
A diagnosis that had often meant progressive immune destruction and death could increasingly become a chronic condition.
Today many people receiving effective treatment can achieve an undetectable viral load.
And when HIV remains undetectable, sexual transmission effectively stops.
Hence one of the most important messages in modern HIV medicine:
U = U
Undetectable = Untransmittable.
That is an extraordinary progression.
Medicine moved from treating the consequences of AIDS to suppressing the virus so effectively that treatment itself became a means of preventing transmission.
Yet HIV has not disappeared.
It remains a major global health problem.
The pandemic became controllable.
It did not become irrelevant.
COVID Arrived in the Same Position — but Not the Same Scientific World
At the beginning of 2020, COVID treatment looked remarkably familiar.
There was no established therapy.
Clinicians supported patients while trying to understand what the disease was doing.
Oxygen.
Fluid management.
Respiratory support.
Treatment of organ failure.
Treatment of secondary complications.
Once again medicine was initially treating the consequences rather than the cause.
But the speed of development was entirely different.
Within months, researchers had established large randomised trials.
The RECOVERY trial demonstrated that dexamethasone reduced mortality in patients requiring oxygen or mechanical ventilation.
Antivirals followed.
Immunomodulatory drugs followed.
Anticoagulation strategies evolved.
Respiratory management improved.
The treatment of COVID changed almost in real time.
What had taken years during HIV/AIDS was, in some respects, happening over months.
So Why Was COVID Science So Much Faster?
The obvious answer is technological progress.
And that is certainly part of it.
Genomic sequencing was vastly faster.
Molecular diagnostics were vastly better.
Computing power had changed beyond recognition.
Vaccine technology had advanced.
Clinical research had become international on a scale that would have been difficult to imagine in 1981.
But where did much of that infrastructure come from?
Partly from HIV/AIDS.
HIV forced scientists to understand viral replication in extraordinary detail.
It drove the development of entire classes of antiviral drugs.
It expanded molecular virology.
It transformed immunology.
It developed international clinical-trial networks.
It created large prevention studies.
It pushed pharmaceutical development.
It forced governments, universities, charities, communities and pharmaceutical companies to work together in ways that had rarely happened before.
It also changed the culture of medical research.
HIV activists challenged the painfully slow pace of traditional drug approval.
Patients demanded a voice in research.
Communities demanded access to experimental treatment.
Clinical trials became larger, faster and more internationally connected.
By the time SARS-CoV-2 appeared, much of that machinery was already sitting there.
It did not need to be invented.
It needed to be redirected.
That does not mean HIV research alone gave us COVID vaccines.
Of course it did not.
Coronavirus research, influenza research, immunology, molecular biology and vaccine-platform development were all essential.
But remove forty years of HIV-driven antiviral and infectious-disease research from the equation and it becomes difficult to believe that COVID would have been tackled at the same speed.
There is an uncomfortable historical irony here.
Millions died while medicine learned how to fight HIV.
Some of the knowledge and infrastructure created because of that tragedy helped save lives during the next major pandemic.
COVID Treatment Was Effective — but It Was Never Simple
One of the mistakes made when looking back at COVID is to imagine that once effective drugs were identified the problem was largely solved.
That is not how critical illness works.
Dexamethasone is a good example.
It reduces harmful inflammation in severe COVID.
But corticosteroids also raise blood glucose.
COVID itself can disturb glucose metabolism.
The result can be profound hyperglycaemia even in somebody without a previous diagnosis of diabetes.
That happened to me.
A blood glucose of approximately 32 mmol/L required active treatment.
Suddenly the problem was no longer simply:
COVID → dexamethasone → recovery.
It had become:
COVID → inflammatory disease → dexamethasone → severe hyperglycaemia → further treatment and monitoring.
Meanwhile respiratory function, neurological function, renal function and the original disease still had to be managed.
This is the reality of intensive care.
One intervention can create another clinical problem.
That complication may require another medicine.
That medicine requires further monitoring.
And all of this occurs in a patient whose physiology is already under extreme stress.
When the Patient Changes Faster Than the Medical Label
Before hospital I was not diabetic.
So when asked:
“Are you diabetic?”
my answer was:
No.
That was accurate according to my medical history.
But it was no longer an adequate description of my current clinical condition.
During the admission I had developed profound hyperglycaemia and had been started on treatment.
The more useful questions would therefore have been:
What is the patient’s blood glucose now?
What medication is the patient receiving now?
What is the renal function now?
What has changed since admission?
Critical illness teaches an important lesson:
the patient in front of you matters more than the historical label attached to them.
Metformin, Contrast and Acute Kidney Injury
This area requires care.
Metformin itself does not directly cause contrast-associated acute kidney injury.
MRI contrast is usually gadolinium-based rather than the iodinated contrast commonly used for CT and angiography.
It would therefore be simplistic and medically inaccurate to say:
metformin + MRI contrast = AKI.
My own experience establishes what happened in sequence.
I had severe COVID.
I developed profound hyperglycaemia.
I received metformin.
I underwent contrast-enhanced MRI.
I subsequently developed acute kidney injury.
My hospital stay was extended by approximately two weeks.
That chronology does not establish a single cause.
Critical COVID itself can involve:
hypoxia,
dehydration,
inflammation,
haemodynamic instability,
renal hypoperfusion,
sepsis,
drug exposure,
metabolic disturbance,
and thrombotic disease.
Several of those factors may interact.
That is exactly why the episode matters.
The lesson is not that one specific drug or investigation was necessarily responsible.
The lesson is that critical illness creates interconnected risk.
The Treatment Cascade
COVID could produce a chain reaction.
COVID
↓
severe inflammatory disease
↓
corticosteroid treatment
↓
hyperglycaemia
↓
glucose monitoring and further medication
At the same time:
COVID
↓
respiratory failure
↓
oxygen / CPAP / ventilation
And potentially:
COVID
↓
abnormal thrombosis
↓
anticoagulation / imaging / further treatment
Every individual intervention may be clinically justified.
But together they create an enormous physiological and therapeutic burden.
This becomes particularly important when deciding whether to escalate treatment in patients with very limited physiological reserve.
Treatment Limitation Was Not Always Rationing
This distinction became badly confused during the pandemic.
Not every patient was suitable for invasive intensive-care treatment.
Mechanical ventilation is not simply a more powerful form of oxygen.
Critical care can involve:
invasive ventilation,
deep sedation,
neuromuscular blockade,
prone positioning,
vasopressors,
renal replacement therapy,
anticoagulation,
corticosteroids,
immunomodulating drugs,
and treatment of secondary infection.
For a relatively fit patient, the body may tolerate that enormous physiological insult long enough to recover.
For someone with profound frailty, irreversible multiorgan disease or terminal illness, the same intervention may merely prolong dying.
Deciding that treatment is unlikely to benefit an individual patient is therefore not necessarily rationing.
It may simply be appropriate medicine.
But genuine rationing is different.
Rationing occurs when treatment could potentially benefit a patient but the healthcare system does not have sufficient capacity to provide it.
COVID brought that possibility frighteningly close.
A Ventilator Is Not an Intensive-Care Bed
One of the great simplifications of the pandemic was the obsession with ventilator numbers.
A ventilator is a machine.
Intensive care is a system.
A functional intensive-care bed requires:
trained nurses,
critical-care doctors,
operating department practitioners,
physiotherapists,
pharmacists,
laboratory services,
radiology,
oxygen infrastructure,
monitoring,
and logistical support.
You can manufacture another ventilator.
You cannot manufacture an experienced intensive-care team overnight.
That difference matters.
A health system can possess equipment and still lack capacity.
Once the number of seriously ill patients exceeds that capacity, medicine faces a very different ethical problem.
Normally the question is:
Can this treatment help this patient?
During severe resource shortage the question becomes:
If several patients could benefit and there is only capacity to treat one, who receives it?
That is genuine rationing.
And no healthcare system wants to be forced into that position.
Frailty and the Danger of Turning Clinical Judgement Into an Algorithm
Frailty became a particularly controversial issue during COVID.
The Clinical Frailty Scale can help clinicians assess physiological reserve in appropriate patients.
But it cannot replace judgement.
A person with a lifelong physical disability is not automatically physiologically frail.
An older person is not automatically unsuitable for intensive care.
A score should assist a clinical decision.
It should never become the clinical decision.
COVID reminded us that algorithms are useful servants and potentially dangerous masters.
What Did People Actually Die From?
Mortality is perhaps the most contentious part of any comparison between AIDS and COVID.
The problem begins with three very different phrases:
died from COVID
died with COVID
died because COVID worsened another disease
These are not the same thing.
A patient develops COVID pneumonia, progresses to respiratory failure and dies.
COVID clearly initiated the fatal process.
Another patient has severe COPD, contracts COVID and rapidly deteriorates.
COVID may still reasonably be considered the precipitating event.
Now consider someone with terminal metastatic cancer who happens to test positive for SARS-CoV-2 but dies because the cancer progresses.
That is different.
Likewise, someone who tests positive and subsequently dies in a road collision has not died because of COVID.
HIV presents exactly the same problem.
A person might die from Pneumocystis pneumonia.
But if HIV caused the immunodeficiency that allowed that infection to become lethal, HIV belongs in the causal chain.
Conversely, someone with well-controlled HIV who dies from an unrelated condition decades later has not necessarily died from HIV/AIDS.
Four Different Types of Pandemic Death
Perhaps the simplest way to understand this is to divide deaths into four groups.
Directly attributable deaths
The infection starts the fatal disease process.
Contributory deaths
The infection significantly worsens another disease and helps precipitate death.
Incidental infection
The infection is present but is not responsible for the fatal event.
Unrecognised infection-related deaths
The infection causes or contributes to death but is never diagnosed or recorded.
Both HIV and COVID contain examples of all four.
Why Post-Mortem Examination Matters
During the emergence of a new disease, clinical diagnosis alone is not enough.
Post-mortem examination can reveal what actually happened.
A presumed COVID respiratory death might demonstrate:
pulmonary embolism,
bacterial pneumonia,
myocardial infarction,
or another pathological process.
Conversely, somebody thought to have died primarily from cardiovascular disease may show extensive pulmonary or vascular damage associated with COVID.
The same occurred during the early AIDS epidemic.
Post-mortem examination revealed opportunistic infections and malignancies that had not always been recognised during life.
Better investigation can therefore move mortality numbers in either direction.
It can identify deaths that were missed.
It can also reveal that a presumed pandemic death had another primary cause.
And Then There Are the Deaths Nobody Recorded
The opposite problem is equally important.
COVID deaths were undoubtedly missed.
In countries with advanced healthcare systems, a patient might have:
a diagnostic test,
hospital assessment,
medical certification,
and formal death registration.
In poorer countries or remote communities, none of that may have happened.
Testing might have been unavailable.
Hospitals might have been inaccessible.
Medical staff might have been absent.
People may have died at home.
Some deaths may never have been medically investigated at all.
This makes international mortality comparisons extraordinarily difficult.
A country reporting fewer COVID deaths may genuinely have experienced less mortality.
Or it may simply have been less capable of identifying it.
This is why excess mortality is so important.
Instead of asking whether COVID appeared on a death certificate, researchers ask:
How many more people died than would normally have been expected?
WHO estimated approximately 14.9 million excess deaths globally during 2020 and 2021.
That figure is substantially higher than officially confirmed COVID deaths over the same period.
But excess mortality should not simply be interpreted as hidden COVID deaths.
It also includes indirect effects:
delayed cancer diagnosis,
disrupted emergency care,
reduced access to routine medicine,
and the wider consequences of overwhelmed healthcare systems.
Both Sides of the Argument Can Be True
This is where debates about COVID mortality often become unnecessarily polarised.
Some people unquestionably died with COVID rather than because of COVID.
At the same time, large numbers of deaths caused or contributed to by COVID were probably never officially recorded as such.
Both things can be true.
The same is true of HIV/AIDS.
Some people living with HIV died from entirely unrelated illnesses.
Yet particularly early in the epidemic, other people almost certainly died from AIDS-related disease without HIV ever being formally identified.
Mortality data therefore need interpretation.
A number in a spreadsheet is not the same thing as a complete clinical history.
HIV and COVID Had Completely Different Mortality Patterns
HIV created a prolonged catastrophe.
Infection accumulated over years.
Untreated patients gradually developed immune failure.
Deaths rose as the epidemic matured.
Then effective antiretroviral therapy fundamentally changed the trajectory.
COVID was different.
Its pressure arrived in waves.
Hospitals could move from manageable workloads to crisis conditions in weeks.
Then mortality declined as:
vaccination increased,
population immunity developed,
treatment improved,
clinical understanding advanced,
and viral variants changed.
Neither disease was simply eliminated.
Both became increasingly manageable.
But they became manageable by entirely different routes.
The Vaccine Difference
Perhaps the most striking contrast is vaccination.
More than forty years after HIV emerged, there is still no routinely effective HIV vaccine.
COVID vaccines were being administered within around a year of SARS-CoV-2 being identified.
Part of that difference lies in biology.
HIV is an extraordinarily difficult vaccine target.
It mutates rapidly.
It integrates into host cells.
It has sophisticated mechanisms for evading immunity.
SARS-CoV-2 presented a far more accessible target.
But the speed of COVID vaccine development also reflected the scientific world inherited from decades of previous research.
Again, HIV was part of that story.
Scientists did not suddenly learn how viruses and immune systems worked in January 2020.
They had spent decades building that knowledge.
Control Follows Biology
The two pandemics also demonstrate why public-health measures must reflect how a disease actually spreads.
HIV control relies upon:
screened blood,
condoms,
sterile injecting equipment,
testing,
antiretroviral treatment,
post-exposure prophylaxis,
and pre-exposure prophylaxis.
COVID required:
testing,
isolation,
ventilation,
respiratory protection,
reducing high-risk exposure,
vaccination,
and protection of vulnerable people.
Different pathogens require different strategies.
Public health fails when ideology is allowed to override biology.
Stigma Failed in Both Pandemics
AIDS demonstrated how damaging disease-related stigma can become.
HIV became associated with homosexuality, injecting drug use and sexual behaviour.
Fear became entangled with morality.
People avoided testing.
Patients experienced discrimination.
Public-health messaging became harder.
COVID produced different divisions.
Vaccinated and unvaccinated.
Mask users and non-mask users.
Those favouring restrictions and those opposing them.
Again, public-health discussions became moralised.
Viruses do not care whether somebody is considered socially responsible or irresponsible.
Disease control works through cooperation, evidence and trust.
Once trust disappears, public-health interventions become considerably harder.
Inequality Determined Who Benefited From Science
HIV also taught us that discovering a treatment does not mean everyone gets it.
Antiretroviral treatment transformed survival in wealthy countries long before comparable access existed globally.
COVID repeated the lesson.
Access differed enormously for:
vaccines,
oxygen,
testing,
antivirals,
intensive-care beds,
and trained clinicians.
Science may create a solution.
Healthcare systems determine whether that solution reaches the patient.
Survival Is Not the Same as Recovery
Perhaps one of the greatest weaknesses in pandemic statistics is the word recovered.
It sounds final.
It often isn’t.
A person may survive COVID while experiencing:
encephalitis,
acute kidney injury,
muscle wasting,
metabolic disturbance,
neurological symptoms,
persistent respiratory problems,
and prolonged rehabilitation.
A mortality figure tells us whether somebody survived.
It tells us almost nothing about what survival cost them.
That matters when evaluating the true burden of a pandemic.
What Did We Actually Learn?
Comparing AIDS with COVID produces several enduring lessons.
Identify the pathogen quickly.
Build research systems before the next crisis arrives.
Test treatments properly rather than relying on theory or enthusiasm.
Understand that effective treatments can create secondary complications.
Treat the patient according to their current physiology, not merely their historical diagnosis.
Do not confuse clinically appropriate treatment limitation with resource rationing.
Do not confuse infection status with cause of death.
Do not assume another underlying disease makes an infection irrelevant.
Maintain strong mortality-registration systems.
Use post-mortem examination to challenge clinical assumptions.
Remember that healthcare capacity is itself a determinant of mortality.
Avoid stigma.
And perhaps most importantly:
remember that surviving a pandemic illness is not necessarily the same thing as returning unchanged to the life you had before it.
Conclusion
HIV/AIDS and COVID-19 were very different pandemics.
But viewed together, they form one continuous story of medical learning.
AIDS appeared in 1981 when medicine initially had very little capable of changing the underlying viral disease.
Patients died while clinicians learned.
Researchers learned how to attack viral replication.
They learned how to combine antivirals.
They built trial networks.
They transformed molecular virology.
They transformed immunology.
They changed drug development.
They changed the relationship between researchers and patients.
Forty years later, COVID arrived.
This time the scientific world was ready in a way it had not been in 1981.
Not perfectly ready.
But incomparably better prepared.
That preparation mattered.
Without HIV/AIDS, it is reasonable to suggest that the response to COVID would probably have taken considerably longer.
The tragedy of AIDS helped build the scientific infrastructure that confronted COVID.
That may be one of the least appreciated legacies of the HIV pandemic.
But COVID also reminded us that science alone is never enough.
A drug can exist but remain unavailable.
A ventilator can exist without the staff required to use it.
A treatment can save a life while creating another clinical problem.
A patient’s physiology can change faster than their medical record.
A death certificate can simplify a complicated causal chain into a single diagnosis.
And a person recorded as “recovered” can leave hospital carrying consequences that remain long after the infection itself has gone.
Perhaps the greatest lesson is therefore not that humanity defeated either pandemic.
We didn’t.
We learned how to manage them.
And each time we do that, the knowledge gained becomes part of the defence against whatever comes next.
HIV/AIDS taught medicine how to confront a modern viral pandemic.
COVID showed us how much we had learned.
The next pandemic will show whether we remembered it.
