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Hydroxychloroquine has been shown not to provide benefit for COVID-19 patients in multiple randomized controlled trials, despite continuous misinformation asserting its alleged effectiveness.

(© Sherry Young/Adobe)

In the early days of a pandemic caused by a virus with no existing treatments, many different compounds are often considered and tried in an attempt to help patients.

It all relates back to a profound question: How do we know what we know?

Many of these treatments fall by the wayside as evidence accumulates regarding actual efficacy. At that point, other treatments become standard of care once their benefit is proven in rigorously designed trials.

However, about seven months into the pandemic, we're still seeing political resurrection of a treatment that has been systematically studied and demonstrated in well-designed randomized controlled trials to not have benefit.

The hydroxychloroquine (and by extension chloroquine) story is a complicated one that was difficult to follow even before it became infused with politics. It is a simple fact that these drugs, long approved by the Food and Drug Administration (FDA), work in Petri dishes against various viruses including coronaviruses. This set of facts provided biological plausibility to support formally studying their use in the clinical treatment and prevention of COVID-19. As evidence from these studies accumulates, it is a cognitive requirement to integrate that knowledge and not to evade it. This also means evaluating the rigor of the studies.

In recent days we have seen groups yet again promoting the use of hydroxychloroquine in, what is to me, a baffling disregard of the multiple recent studies that have shown no benefit. Indeed, though FDA-approved for other indications like autoimmune conditions and preventing malaria, the emergency use authorization for COVID-19 has been rescinded (which means the government cannot stockpile it). Still, however, many patients continue to ask for the drug, compelled by political commentary, viral videos, and anecdotal data. Yet most doctors (like myself) are refusing to write the prescriptions outside of a clinical trial – a position endorsed by professional medical organizations such as the American College of Physicians and the Infectious Diseases Society of America. Why this disconnect?

It all relates back to a profound question: How do we know what we know? In science, we use the scientific method – the process of observing reality, coming up with a hypothesis about what might be true, and testing that hypothesis as thoroughly as possible until we discover the objective truth.

The confusion we're seeing now stems from an inability to distinguish between anecdotes reported by physicians (observational data) and an actual evidence base. This is understandable among the general public but when done by a healthcare professional, it reveals a disdain for reason, logic, and the scientific method.

The Difference Between Observational Data and Randomized Controlled Trials

The power of informal observation is crucial. It is part of the scientific method but primarily as a basis for generating hypotheses that we can test. How do we conduct medical tests? The gold standard is the double-blind, randomized, placebo-controlled trial. This means that neither the researchers nor the volunteers know who is getting a drug and who is getting a sugar pill. Then both groups of the trial, called arms, can be compared to determine whether the people who got the drug fared better. This study design prevents biases and the placebo effect from confounding the data and undermining the veracity of the results.

For example, a seemingly beneficial effect might be seen in an observational study with no blinding and no control group. In such a case, all patients are openly given the drug and their doctors observe how they do. A prime example is the 36-patient single-arm study from France that generated a tremendous amount of interest after President Trump tweeted about it. But this kind of a study by its nature cannot answer the critical question: Was the positive effect because of hydroxychloroquine or just the natural course of the illness? In other words, would someone have recovered in a similar fashion regardless of the drug? What is the role of the placebo effect?

These are reasons why it is crucial to give a placebo to a control group that is as similar in every respect as possible to those receiving the intervention. Then we attempt to find out by comparing the two groups: What is the side effect profile of the drug? Are the groups large enough to detect a relatively rare safety concern? How long were the patients followed for? Was something else responsible for making the patients get better, such as the use of steroids (as likely was the case in the Henry Ford study)?

Looking at the two major hydroxychloroquine trials, it is apparent that, when studied using the best tools of clinical trials, no benefit is likely to occur.

All of these considerations amount to just a fraction of the questions that can be answered more definitively in a well-designed large randomized controlled trial than in observational studies. Indeed, an observational study from New York failed to show any benefit in hospitalized patients, showing how unclear and disparate the results can be with these types of studies. A New York retrospective study (which examined patient outcomes after they were already treated) had similar results and included the use of azithromycin.

When evaluating a study, it is also important to note whether conflicts of interest exist, as well as the quality of the peer review and the data itself. In the case of the French study, for example, the paper was published in a journal in which one of the authors was editor-in-chief, and it was accepted for publication after 24 hours. Patients who fared poorly on hydroxychloroquine were also left out of the study altogether, skewing the results.

What Randomized Controlled Trials Have Shown

Looking at the two major hydroxychloroquine trials, it is apparent that, when studied using the best tools of clinical trials, no benefit is likely to occur. The most important of these studies to announce results was part of the Recovery trial, which was designed to test multiple interventions in the treatment of COVID-19. This trial, which has yet to be formally published, was a randomized controlled trial that involved over 1500 hospitalized patients being administered hydroxychloroquine compared to over 3000 who did not receive the medication. Clinical testing requires large numbers of patients to have the power to demonstrate statistical significance -- the threshold at which any apparent benefit is more than you would expect by random chance alone.

In this study, hydroxychloroquine provided no mortality benefit or even a benefit in hospital length of stay. In fact, the opposite occurred. Hydroxychloroquine patients were more likely to stay in the hospital longer and were more likely to require mechanical ventilation. Additionally, smaller randomized trials conducted in China have not shown benefit either.

Another major study involved the use of hydroxychloroquine to prevent illness in people who were exposed to COVID-19. These results, published in The New England Journal of Medicine, included over 800 patients who were studied in a randomized double-blind controlled trial and also failed to show any benefit.

But what about adding the antibiotic azithromycin in conjunction with hydroxychloroquine? A three-arm randomized controlled study involving over 500 patients hospitalized with mild to moderate COVID-19 was conducted. Its results, also published in The New England Journal of Medicine, failed to show any benefit – with or without azithromycin – and demonstrated evidence of harm. Those who received these treatments had elevations of their liver function tests and heart rhythm abnormalities. These findings hold despite the retraction of an observational study showing similar results.

Additionally, when used in combination with remdesivir – an experimental antiviral – hydroxychloroquine has been shown to be associated with worse outcomes and more side effects.

But what about in mildly ill patients not requiring hospitalization? There was no benefit found in a randomized double-blind placebo-controlled trial of 400 patients, the majority of whom were given the drug within one day of symptoms.

Some randomized controlled studies have yet to report their findings on hydroxychloroquine in non-hospitalized patients, with the use of zinc (which has some evidence in the treatment of the common cold, another ailment that can be caused by coronaviruses). And studies have yet to come out regarding whether hydroxychloroquine can prevent people from getting sick before they are even exposed. But the preponderance of the evidence from studies designed specifically to find benefit for treating COVID-19 does not support its use outside of a research setting.

Today – even with some studies (including those with zinc) still ongoing – if a patient asked me to prescribe them hydroxychloroquine for any severity or stage of illness, with or without zinc, with or without azithromycin, I would refrain. I would explain that, based on the evidence from clinical trials that has been amassed, there is no reason to believe that it will alter the course of illness for the better.

Failing to recognize the reality of the situation runs the risk of crowding out other more promising treatments and creating animosity where none should exist.

What has been occurring is a continual shifting of goalposts with each negative hydroxychloroquine study. Those in favor of the drug protest that a trial did not include azithromycin or zinc or wasn't given at the right time to the right patients. While there may be biological plausibility to treating illness early or combining treatments with zinc, it can only be definitively shown in a randomized, controlled prospective study.

The bottom line: A study that only looks at past outcomes in one group of patients – even when well conducted – is at most hypothesis generating and cannot be used as the sole basis for a new treatment paradigm.

Some may argue that there is no time to wait for definitive studies, but no treatment is benign. The risk/benefit ratio is not the same for every possible use of the drug. For example, hydroxychloroquine has a long record of use in rheumatoid arthritis and systemic lupus (whose patients are facing shortages because of COVID-19 related demand). But the risk of side effects for many of these patients is worth taking because of the substantial benefit the drug provides in treating those conditions.

In COVID-19, however, the disease apparently causes cardiac abnormalities in a great deal of many mild cases, a situation that should prompt caution when using any drugs that have known effects on the cardiac system -- drugs like hydroxychloroquine and azithromycin.

My Own Experience

It is not the case that every physician was biased against this drug from the start. Indeed, most of us wanted it to be shown to be beneficial, as it was a generic drug that was widely available and very familiar. In fact, early in the pandemic I prescribed it to hospitalized patients on two occasions per a hospital protocol. However, it is impossible for me as a sole clinician to know whether it worked, was neutral, or was harmful. In recent days, however, I have found the hydroxychloroquine talk to have polluted the atmosphere. One recent patient was initially refusing remdesivir, a drug proven in large randomized trials to have effectiveness, because he had confused it with hydroxychloroquine.

Moving On to Other COVID Treatments: What a Treatment Should Do

The story of hydroxychloroquine illustrates a fruitless search for what we are actually looking for in a COVID-19 treatment. In short, we are looking for a medication that can decrease symptoms, decrease complications, hasten recovery, decrease hospitalizations, decrease contagiousness, decrease deaths, and prevent infection. While it is unlikely to find a single antiviral that can accomplish all of these, fulfilling even just one is important.

For example, remdesivir hastens recovery and dexamethasone decreases mortality. Definitive results of the use of convalescent plasma and immunomodulating drugs such as siltuxamab, baricitinib, and anakinra (for use in the cytokine storms characteristic of severe disease) are still pending, as are the trials with monoclonal antibodies.

While it was crucial that the medical and scientific community definitively answer the questions surrounding the use of chloroquine and hydroxychloroquine in the treatment of COVID-19, it is time to face the facts and accept that its use for the treatment of this disease is not likely to be beneficial. Failing to recognize the reality of the situation runs the risk of crowding out other more promising treatments and creating animosity where none should exist.

Amesh A. Adalja
Dr. Adalja is a Senior Scholar at the Johns Hopkins University Center for Health Security. His work is focused on emerging infectious disease, pandemic preparedness, and biosecurity. He has served on US government panels tasked with developing guidelines for the treatment of plague, botulism, and anthrax in mass casualty settings and the system of care for infectious disease emergencies, and as an external advisor to the New York City Health and Hospital Emergency Management Highly Infectious Disease training program, as well as on a FEMA working group on nuclear disaster recovery. Dr. Adalja is an Associate Editor of the journal Health Security. He was a coeditor of the volume Global Catastrophic Biological Risks, a contributing author for the Handbook of Bioterrorism and Disaster Medicine, the Emergency Medicine CorePendium, Clinical Microbiology Made Ridiculously Simple, UpToDate’s section on biological terrorism, and a NATO volume on bioterrorism. He has also published in such journals as the New England Journal of Medicine, the Journal of Infectious Diseases, Clinical Infectious Diseases, Emerging Infectious Diseases, and the Annals of Emergency Medicine. He is a board-certified physician in internal medicine, emergency medicine, infectious diseases, and critical care medicine.

A lab tech handling a sample of the novel coronavirus.

(© JHDT Productions/Adobe)


One of the main factors that will influence the ultimate trajectory of the novel coronavirus pandemic will be the availability of a vaccine.

Vaccine development has traditionally been a process measured in years and even decades.

Vaccines are incontrovertibly the best means to control infectious diseases and there are no human vaccines against any of the (now) 7 known human coronaviruses. As soon as the gravity of this outbreak was recognized, several companies, along with governmental and non-governmental partners, have embarked on a rapid development program to develop a vaccine targeted at this virus.

Vaccine development has traditionally been a process measured in years and even decades as scientists tinker with a pathogen trying to weaken or dissemble it to render it capable of creating an effective immune response with acceptable levels of side effects. However, in 2020, powerful new vaccine technologies are available to augment traditional vaccine development and are responsible for the rapid delivery of a vaccine candidate for the start of clinical trials.

Vaccine Platforms: A Game-Changing Technology

The new technologies that are being harnessed are what are known as vaccine platform technologies. Vaccine platforms, as my colleagues and I wrote in a report assessing their promise, offer a means to use the same building blocks to make more than one vaccine. To slightly oversimply, a vaccine platform confers the ability to switch out the pathogen being targeted very rapidly, akin to changing a video game cartridge. Indeed, the recently FDA-licensed Ebola vaccine uses another virus as a platform with the requisite Ebola protein inserted.

Because of this rapid availability to utilize platforms for a variety of different targets, the initial development process can be significantly shortened. This is especially true for vaccines utilizing the genetic material of the target alone. These DNA and RNA vaccines basically can be "printed" once the genetic sequence of the target is known.

An RNA vaccine is the approach being used by the Cambridge-based biotech company Moderna – which took just 42 days to produce an experimental vaccine candidate. Clinical testing is expected to begin next month on 45 healthy volunteers.

Another biotech, the Pennsylvania-based Inovio, is using a DNA approach. In essence, such vaccines involve the genetic material being injected and translated into a viral protein by human cells, which then prompt the immune system to make antibodies.

There are other approaches as well. One company, the Maryland-based Novavax, will use nanoparticles, while another is attempting to adapt an orally administered avian coronavirus vaccine and Johnson & Johnson is using different virus platforms to deliver coronavirus proteins (similar to their experimental Ebola vaccine).

At this stage, it is important for all approaches to be on the table in the hope that at least one makes it through clinical trials. There also may be a need for different types of vaccines for different populations.

Vaccines Will Still Take Time

Despite the quick development time made possible by the use of vaccine platforms, clinical testing for safety, efficacy, and dosing schedules will still take months to complete. After this process, the vaccine will need to be mass produced in large quantities to vaccinate, basically, the world. So, for all intents and purposes, we cannot expect to see an approved vaccine for at least a year or maybe longer if everything does not go perfectly well in clinical trials.

Vaccine platform technologies offer a bright ray of hope in the bleak shadow of the pandemic.

Once a vaccine is available, it will likely appear in batches to be distributed to those at highest risk for severe disease, such as the elderly and those with underlying conditions, as well as healthcare workers, first. At this time, it appears children are less likely to experience severe illness and they may not be the first targets for the vaccine but, if this virus is with us (as is predicted), coronavirus vaccination could become part of routine childhood vaccinations.

Changing Pandemic Trajectory

Vaccination will not come fast enough to impact the initial wave of the novel virus which may continue until summer approaches in temperate climates. However, it will be a crucial tool to blunt the impact of a future appearance in the following respiratory virus season. This reappearance is all but assured as this virus has adeptly established itself in human populations and is behaving like the community-acquired coronavirus that it is.

A Glimmer of Hope

When looking at the trajectory of the virus, it can appear, thus far, that no public health effort has made a substantial impact on the spread of the virus. However, that trajectory will change with the advent of an efficacious vaccine. Such a vaccine, especially if conferring protection against other human coronaviruses, may result in coronaviruses being taken off the table of biological threats altogether in the future.

Vaccine platform technologies offer a bright ray of hope in the bleak shadow of the pandemic and, if successful, will change the way the world approaches future pandemic threats with more rapid deployment of platform-based vaccines.

Amesh A. Adalja
Dr. Adalja is a Senior Scholar at the Johns Hopkins University Center for Health Security. His work is focused on emerging infectious disease, pandemic preparedness, and biosecurity. He has served on US government panels tasked with developing guidelines for the treatment of plague, botulism, and anthrax in mass casualty settings and the system of care for infectious disease emergencies, and as an external advisor to the New York City Health and Hospital Emergency Management Highly Infectious Disease training program, as well as on a FEMA working group on nuclear disaster recovery. Dr. Adalja is an Associate Editor of the journal Health Security. He was a coeditor of the volume Global Catastrophic Biological Risks, a contributing author for the Handbook of Bioterrorism and Disaster Medicine, the Emergency Medicine CorePendium, Clinical Microbiology Made Ridiculously Simple, UpToDate’s section on biological terrorism, and a NATO volume on bioterrorism. He has also published in such journals as the New England Journal of Medicine, the Journal of Infectious Diseases, Clinical Infectious Diseases, Emerging Infectious Diseases, and the Annals of Emergency Medicine. He is a board-certified physician in internal medicine, emergency medicine, infectious diseases, and critical care medicine.