Can online searches help health authorities identify new symptoms of COVID-19? 

With increased internet penetration, can online search data contribute to the identification of new symptoms for COVID-19? Google Trends data shows that newly recognized symptoms were already prevalent in online searches.

Since the release of the first protocol for the clinical management of COVID-19 by India’s Ministry of Health in March, there has been an addition of new symptoms observed in COVID-19 patients. The most recent version of the protocol, released in July identifies eleven symptoms, an increase from three – fever, cough, and shortness of breath that were previously identified as the most common symptoms of the disease. In April, the Centers for Disease Control and Prevention (CDC) similarly added six new symptoms to its initial list of COVID-19 symptoms.

Fever, most prevalent symptom among patients but cough and headache most googled symptoms of COVID-19

Fever continues to be the most prevalent symptom in clinical observations of patients across the globe.

In the World Health Organization’s first publication of the clinical features of COVID-19 patients in China, 87.9% of the 55,924 laboratory-confirmed cases reported a fever. A report published by the International Severe Acute Respiratory and Emerging Infections Consortium’s in May, covering 25,849 hospitalized patients similarly found fever, shortness of breath, cough, fatigue, and confusion to be the five most common symptoms. In India, the Integrated Disease Surveillance Programme’s case investigation of 15,336 patients also reported fever as the most prevalent symptom of COVID-19.

The most googled symptom of COVID-19, however, is cough. Globally, Google recorded a higher relative search index for a cough than other common symptoms – fever, shortness of breath, and fatigue.

Popular searches related to cough were “dry cough”, “tickly/itchy cough”, “wet cough”, “no cough and coronavirus”, “phlegm cough” and “persistent cough and coronavirus”.

Headache, which is currently listed as a less common symptom by the WHO, was more searched than more common symptoms such as fever and fatigue. Although the headache was observed in earlier studies, it was only reported by a minority of patients. In the study of 55924 confirmed cases in China, only 13.6% reported having a headache, a much lower percentage compared to the prevalence of cough, fatigue, and even sputum production. Headache has been identified as a primary symptom in some studies, however, these are based on small sample sizes.

Searches related to fever were interestingly about the possibility of having coronavirus without symptoms of fever. “No fever coronavirus”, “Chills and no fever”, “Low/Mild fever” and “Cough/sore throat without fever coronavirus” were some of the most popular searches on Google Search.

Can aggregated searches signal to new symptoms?   

Google Trends data shows that the newly recognized symptoms of COVID-19 were predominant in earlier searches related to COVID-19. Loss of smell and taste, for example, was recognized by the CDC in late April, but they have been dominating online searches since March. Searches related to these symptoms peaked in the last week of March, nearly a month before they were officially recognized as symptoms. Similarly, “chills and coronavirus” was searched for as early as January, pointing to the possible utility of aggregated search data in signaling to potential new symptoms.