Table 1.

Articles that raised the possibility of predicting the development of COVID-19.

Study (Author)	Search engine	Territory	Terms of interest	Time lag
Li et al [12]	Google Trends, Baidu Index, and Sina Weibo Index	China	“Coronavirus” and “Pneumonia”	6-8 days
Husnayain et al [13]	Google Trends	Taiwan	“Handwashing” and “Mask Related Information”	1-3 days
Effenberger et al [14]	Google Trends	China, Republic of Korea, Japan, Iran, Italy, Austria, Germany, United Kingdom, United States, Egypt, Australia, and Brazil	“Coronavirus (Virus)”	11.5 days
Pekoz et al [15]	Google Trends	United States	“Sore Throat,” “Fever,” and Cough	1-2 weeks
Yuan et al [16]	Google Trends	United States	“COVID Pneumonia” and “COVID Heart”	Approximately 12 days
Higgins et al [17]	Google Trends and Baidu Index	China, worldwide data, Italy and Spain, and the US states of New York and Washington	“Shortness of Breath,” “Anosmia,” “Dysgeusia,” “Ageusia,” “Headache,” “Chest Pain,” “Sneezing,” “Diarrhea,” “Fever,” “Cough,” “Nasal Obstruction,” and “Rhinorrhea”	12 days
Lu and Reis [18]	Google Trends	32 countries	“Coronavirus Symptoms,” “Coronavirus Test,” “Fever,” “Cough,” “Coronavirus,” “Runny Nose,” “Dry Cough,” “Sore Throat,” “Chills,” and “Shortness of Breath”	18-22 days