3 lessons from our immune systems on how to tackle COVID-19

To provide physicians with actionable insights which can inform treatment decisions, the medical world is leveraging a very sensitive and accurate natural detection system: the human immune system.

This intricate network of cells, signals, organs and lymph nodes works in pursuit of one goal: the protection of the body from disease through the identification and killing of invading pathogens. The key to our immune system’s success is its ability to differentiate between cells that belong in the body and those that don’t, in order to prompt an immune response and the production of antibodies to eliminate the invaders. Incredibly complex yet efficient, the human immune system grows stronger after each infection. Memory cells allow us to prepare for repeat attacks from pathogens by developing immunity to what came before, enabling a swift response.

However, it isn’t perfect. While the immune system deals with threats every day of our lives, cancers, bacterial infections and viruses such as COVID-19 are realities that challenge both the body’s defences and our own healthcare networks.

Information about how to manage COVID-19 patients is at a premium. More than nine months into the pandemic, the bewildering variety of COVID-19 patient experiences still presents a clinical conundrum. While there is evidence of a hyper-inflammatory immune response in critically ill patients, which can lead to acute respiratory distress syndrome (ARDS) and multiple organ failure, the virus is still surrounded by questions. Why do some people become extremely ill, but not others? Why do symptoms vary so drastically among patients? Why is the virus so weakly immunogenic? Will vaccination work for everyone, or only for some?

As well as endeavouring to answer these questions, we believe that following and decoding the signals emitted by our immune systems in response to an infection could be key to enabling improved COVID-19 patient management in the following three ways:

1. Predicting disease severity and progression: Which COVID-19 patients should physicians admit to the hospital, and which patients can safely wait it out at home in isolation? Knowing the answer can be the difference between life and death. As well as minimizing loss of life and severe illness, it’s critical that we also keep infection rates low and hospital beds free in order to prevent overload of the healthcare system. By monitoring predictive biomarkers we could help to identify early those patients who will go on to have severe reactions to COVID-19 and accurately predict the disease's progression, which could ease the giant logistical burden presented by the virus.

2. Monitoring response to treatment: In the majority of COVID-19 patients, the host mounts a localized immune response which is sufficient to clear the virus from the upper airways and lungs. However, in some patients, hyper-inflammation can be triggered, which has been implicated in acute lung injury, organ failure and mortality. As not everyone is liable to exhibit this immune dysregulation, the issue for physicians becomes one of treatment personalization. The absence of a way to continuously measure COVID-19-induced hyper-inflammation means that physicians can miss the right time to treat with corticosteroids, or to take other measures to prevent a patient worsening. Host immune response-based monitoring may provide a quick way to stay in touch with the status of a patient to avoid underdosing and overdosing in these kinds of critical scenarios.

3. Driving improved antibiotic stewardship: The problem of antibiotic overuse isn’t new, but the threat it poses to global public health is accelerating amid the pandemic. We’re simply treating too many COVID-19 patients with antibiotics, in too many instances, when they are not needed. This overuse is cultivating further antibiotic resistance, which means that the drugs won’t work for those who do need them.

When a patient presents with what appears to be an acute infection, physicians across the world face a seemingly simple question: should antibiotic treatment be prescribed or not? The answer is not always simple, as bacterial and viral infections can present very similar symptoms and are often clinically indistinguishable. Host immune response-based solutions can help physicians to quickly rule out if their patients are infected with a bacterial pathogen, preventing unwarranted administration of antibiotics and focusing next steps in the patient’s work-up during a COVID-19 infection. This is also critical in cases of co-infection, where a COVID-19 patient has an additional bacterial infection that does require antibiotic treatment.

By design, the human immune system detects and fights infections, and this is true also for SARS-CoV-2 – the virus which causes COVID-19 – despite the unique myriad of responses it triggers. With new technology, we can harness the signalling power of the human immune system, and work in step with it to find a path forward to defeating the virus. If we ask the right questions, follow the data, and treat in the right ways, then answers to the perplexing questions that COVID-19 has presented us with may soon be within our reach.