Study design
SARS, primary tastes, taste sensations, loss of taste sensation, COVID-19 infection, gustatory dysfunction, loss of taste or smell
SYSTEMIC DISEASE, COVID-19 INFECTION
The study was a prospective, randomized (1:1), blinded clinical trial. The randomization ensures that an equal number of participants are assigned to each group using a random block design with blocks of sizes 2, 4, and 6 within each group. Patients were not aware of the type of treatment they were receiving. After recovery from COVID-19, 36 patients in the study complained of persistent loss of taste sensation. The selection of patients was determined by inclusion and exclusion criteria. The inclusion criteria include Adults (> 18 years old) with a positive test for SARS CoV- 2 via reverse transcription polymerase chain reaction (RT-PCR). After recovering from the COVID-19 infection, patients continued to experience a persistent loss of 4 basic taste sensations for at least four weeks after COVID-19 recovery. Patients with pre-existing olfactory or gustatory dysfunction without a laboratory-confirmed COVID-19 infection diagnosis, pregnant women, patients with any systemic disease, patients who received any treatment to accelerate gustatory function recovery, or taking any medications that cause loss of taste or smell were excluded from the study.The patients were randomly assigned (1:1) to one of the two groups according to the treatment they received: Group I (laser treatment), where each patient received a diode laser treatment, and Group II (light treatment), where each patient was received placebo by the same operator (Fig. 
Consort statement flow chartDemographic data were recorded for all the patients: age, gender, previous clinical history, and swab positivity. COVID-19 signs and symptoms were detected in patients’ clinical records. The patients were interviewed to obtain a detailed timeline of loss of taste sensation regarding the onset and severity. A standardized and validated test was performed preoperatively to evaluate the gustatory function. The test investigates the ability to perceive four primary tastes (sweet, salty, sour, and bitter). The primary predictor variable was the treatment method used. The patients and assessors were blinded throughout the period of the study.