Study Reveals 6 Types of Covid-19 Symptom Clusters to Understand Disease Severity

At the start of the COVID-19 pandemic, only three basic symptoms of the infection were noted: fever, dry cough and shortness of breath. But, over the months, more symptoms have been included to this list as more research on the disease was conducted by scientists around the globe. Apart from the classical symptoms, loss of smell (anosmia), headaches, muscle pains, fatigue, diarrhoea, confusion and loss of appetite have also been reported by patients of COVID-19.

New study to determine the severity of COVID-19

However, determining which of these symptoms can lead to the most severe forms of the disease – and require hospitalisation and ventilator support – has posed more of a question for doctors and healthcare professionals around the world. A new study conducted by researchers at the King’s College London, UK, throws better light into how these symptoms can be categorized to determine the need for respiratory support for COVID-19 patients during hospitalisation.

The study, available in its pre-print version on medRxiv, used data provided by the COVID Symptom Study Smartphone application in the UK and US. The researchers shortlisted 1,600 COVID-19 patients from both countries and observed their symptoms over March-April 2020. The analysis of the data revealed six different types or clusters of symptoms and an algorithm was created based on it. The algorithm was then tested on a second set of 1,000 COVID-19 patients logging their symptoms in May 2020.

Six clusters or types of COVID-19

The researchers narrowed down to the following six clusters of symptoms and classified them according to the possible severity and need for respiratory support during hospitalisation.

1. “Flu-like” symptoms with no fever: Apart from having no fever, these COVID-positive patients experienced headache, loss of smell, muscle pains, cough, sore throat and chest pain. The study showed that only 1.5% of these patients go on to require oxygen support at a later date.

2. “Flu-like” symptoms with fever: These patients have fever as a symptom apart from the ones mentioned in Cluster 1. And yet, the study found that only 1.4% of the patients required ventilators later.

3. Gastrointestinal symptoms: The patients in this cluster had diarrhoea as an additional symptom apart from the ones mentioned in Cluster 1, and 3.3% required oxygen support.

4. Severe level one, fatigue: Fever, loss of smell, headache, cough, hoarse voice, chest pain and fatigue – a whopping 8.6% of COVID-19 patients with these symptoms required ventilator support as the disease progressed.

5. Severe level two, confusion: Brain fog or confusion, apart from the Cluster 4 symptoms showed up in many patients. 9.9% of these patients went on to require additional oxygen support through ventilators.

6. Severe level three, abdominal and respiratory: The patients who had symptoms of fever, headache, loss of smell, loss of appetite, cough, sore throat, hoarse voice, fatigue, confusion, muscle pain, shortness of breath, chest pain, diarrhoea and abdominal pain were put in the severest of all categories. 19% of these patients required oxygen support.

While this study is still in pre-print stage, if it does get peer-reviewed and published, it’ll have major implications for the clinical management of COVID-19, especially in case of a second wave of coronavirus infections.

For more information, read our article on Mild versus severe symptoms of COVID-19.

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