How Covid-19 affects those with rare immune disorders and what it means for the rest of us

  • Covid-19 patients with rare immune disorders may provide insight into what immune characteristics could lead to severe infection
  • These disorders were found not to be a high-risk factor for severe Covid-19
  • Patients’ mortality rate was the same as among the general population

There has been little study on how Covid-19 affects immuno-compromised individuals and how many of them actually survive the disease.

According to a new report to be published in the Journal of Allergy and Clinical Immunology, the reaction of these people to SARS-CoV-2 might just provide some valuable insights into fighting infection and severe Covid-19.

READ | Why does Covid-19 differ so much from patient to patient? T cells may hold the answer

Retrospective study

The researchers made a call to the global medical and scientific community for case studies on Covid-19 patients with rare inborn errors of immunity (IEI). Their call was answered with data from 94 IEI patients who battled the disease.

Contrary to expectation, the patients weren't old. Their average age was between 25 and 34 years (including children), and just more than half suffered from primary antibody deficiency. Other disorders included immune dysregulation syndromes, phagocyte defects, auto-inflammatory disorders and bone marrow failure.

Before infection, all the patients were classified as stable on their normal treatment programmes, with two already on ACE-inhibitor medication. 

Patient outcomes

Of the 94 subjects, 10 were asymptomatic; 25 were treated as outpatients; 28 required hospital admission without intensive care or ventilation; 13 required non-invasive ventilation or oxygen administration; and 18 were admitted to ICU. 

From those in intensive care, 12 required invasive ventilation and three were administered extracorporeal membrane oxygenation.

The most common symptoms were fever, cough, runny nose/sneezing and shortness of breath. Some patients also suffered from gastrointestinal issues, muscle pain, fatigue, sore throat, loss of smell and taste, and anaemia.

READ MORE | Covid infection: Scientists think blood type plays a role, and have identified which one is least at risk

Comorbidities still main factor

More than 30% of the patients only suffered from mild Covid-19, but the risk factors and mortality rate for those with severe infection were found to be similar to the rest of the population without immune disorders. 

Some of these risk factors included comorbidities like hypertension, obesity, diabetes, lung and heart disease, age and sex. This means that having an IEI isn’t necessarily a predominant risk factor for Covid-19.

From the cohort, nine of the patients died, including two children. However, it’s unclear how much Covid-19 contributed to their deaths rather than their IEIs, and the adults who passed away had other existing comorbidities like chronic heart, lung and kidney diseases, hypertension and diabetes. During the course of the disease, many of these patients suffered from hypotension and kidney failure.

“The association between outcome (alive/dead) and the onset of respiratory insufficiency, the presence of comorbidities or the sex of the patient was not significantly different between patients who survived or patients who succumbed to SARS-CoV-2,” write the researchers. 

“Moreover, no correlation could be found between outcome and respiratory insufficiency, age groups or [primary immunodeficiency] type."

READ | More evidence shows why Covid mortality rate is higher in men

Treatment

The treatment strategies for the full cohort included antibiotics, immunoglobulin replacement, hydroxychloroquine/chloroquine, steroids, antivirals, monoclonal antibodies and an anticoagulant. Five patients received convalescent plasma therapy alongside other treatments – and only one of them died.

Through their study, the researchers also discovered specific characteristics of the immune system that potentially led to asymptomatic/mild and severe cases. 

Those with a defect in the adaptive immune system all recovered and didn’t suffer from severe Covid-19. 

“Thus, certain components of adaptive immunity do not appear to be essential for controlling SARS-CoV-2 infection. Rather, these adaptive immune deficiencies may even contribute to a milder course by reducing the immune-mediated sequelae. 

“This is consistent with findings that patients with IEIs that specifically affect B and T cell development or function do not exhibit increased susceptibility to severe disease caused by influenza infection.”

READ | Cape Town hospitals prove oxygen therapy can improve Covid-19 patients' survival rate

Other findings

They infer from their data that the genes IL-6/STAT3 also contributed to disease severity – previous studies have already shown how certain genes could contribute to severe infection by the coronavirus.

“Since auto-immunity is a frequent manifestation of [common variable immunodeficiency (CVID)], it can be hypothesised that the presence or absence of anti-type [one interferon] autoantibodies predisposed CVID patients to either life-threatening or mild disease following SARS-CoV-2 infection.”

Alongside these antibody findings, more research on IEI patients in the pandemic would not only be beneficial for their treatment but also for the general population.

READ MORE | Covid-19 virus and antibodies can coexist in children, new study finds

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