Onset, duration and unresolved symptoms, including smell and taste changes, in mild COVID-19 infection: a cohort study in Israeli patients

Abstract

Objectives: To characterize longitudinal symptoms of mild coronavirus disease 2019 (COVID-19) patients for a period of 6 months, to potentially aid in disease management.

Methods: Phone interviews were conducted with 103 patients with mild COVID-19 in Israel over a 6-month period (April 2020 to October 2020). Patients were recruited via social media and word to mouth and were interviewed up to 4 times, depending on reports of their unresolved symptoms. Inclusion criteria required participants to be residents of Israel aged 18 years or older, with positive COVID-19 real-time PCR results and nonsevere symptoms. The onset, duration, severity and resolution of symptoms were analysed.

Results: A total of 44% (45/103), 41% (42/103), 39% (40/103) and 38% (39/103) of patients experienced headache, fever, muscle ache and dry cough as the first symptom respectively. Smell and taste changes were experienced at 3.9 ± 5.4 and 4.6 ± 5.7 days (mean ± standard deviation (SD)) after disease onset respectively. Among prevalent symptoms, fever had the shortest duration (5.8 ± 8.6 days), and taste and smell changes were the longest-lasting symptoms (17.2 ± 17.6 and 18.9 ± 19.7 days; durations censored at 60 days). Longer recovery of the sense of smell correlated with the extent of smell change. At the 6-month follow-up, 46% (47/103) of the patients had at least one unresolved symptom, most commonly fatigue (22%, 23/103), smell and taste changes (15%, 15/103 and 8%, 8/103 respectively) and breathing difficulties (8%, 8/103).

Conclusions: Long-lasting effects of mild COVID-19 manifested in almost half of the participants reporting at least one unresolved symptom after 6 months.

Keywords: COVID-19; Disease course; Recovery; Smell change; Symptoms duration; Taste change; Unresolved symptoms.

Graphical abstract

Fig. 1

Study design. Each of 4 interviews (initial interview, then 3-week, 6-week and 6-month follow-ups) is presented, with number of participants and start and end dates.

Fig. 2

Symptoms' order of appearance. List of symptoms is on y-axis; number of days after disease onset, x-axis. Mean ± standard deviation (SD) number of days after disease onset is presented for each symptom. Colour bar represents prevalence, with darkest colour indicating most prevalent symptoms.

Fig. 3

Symptoms' durations. (A) List of symptoms is on y-axis; censored duration (days), x-axis. Standard deviation (SD) is presented as dashed line; 95% confidence interval, solid line. Censored mean ± SD duration is presented for each symptom. Censoring was done at 60 days for each duration. Colour bar represents prevalence, with darkest colour indicating most prevalent symptoms. (B) Duration of smell and taste changes are presented in bar charts and marked according to symptom's resolution, with pink representing resolved symptoms and red unresolved symptoms. Percentage of patients is shown on y-axis and duration of symptoms (days) on x-axis.

Fig. 4

Unresolved symptoms. Euler diagram of main unresolved symptoms collected at 6 months' follow-up. Number of patients experiencing unresolved symptom is indicated for each circle.