What do we Know about smell and taste dysfunction by SARS-CoV-2.Predictive value of the Venezuelan Olfactory test and RT-PCR analysis in viral infection diagnosis

BackgroundSmell and taste disorders are reported very frequently and at an early stage in the evolution of the infectious disease caused by the SARS-CoV-2. These symptoms could be sensitive and specific to establish the condition of the infection, and may suggest the flow of decisions as to further therapy. We asked whether smell and taste impairment are earlier and more sensitive symptoms than the RT-PCR molecular assays for SARS-CoV-2 detection. MethodologySubjects (N=275) with a probable COVID19 diagnosis were classified as follows: Symptomatic with chemosensory dysfunction, symptomatic without chemosensory dysfunction, and asymptomatic. Subjects received a general clinical and otorhinolaryngology examination. Evaluation of the chemosensory dysfunction was performed by means of the Venezuelan Olfactory Test and taste test. Nasal swabs and blood samples were analyzed by real-time polymerase chain reaction analysis (RT-PCR) and a rapid diagnostic test to detect the SARS-CoV-2 virus and antiviral antibodies, respectively. Patients had access to molecular tests and smell and taste evaluations every 3 to 5 days until they recovered. ResultsOut of 44 patients that were positive for RT-PCR SARS-CoV-2: 45.83% had smell and taste disorders and COVID19 symptoms, 23.61% did not have smell or taste disorders, but had COVID19 symptoms, and 30.55% were asymptomatic. Mild hyposmia and hypogeusia account for the most frequent chemosensory disorders accompanying common SARS-CoV-2 symptoms. Time to recover from the chemosensory dysfunction ranges from 3 to 14 days, up to a maximum of 5 weeks, while RT-PCR becomes negative after 21 days and up to 35 days in some cases. The Venezuelan Olfactory Test and taste test has a 61.68% positive predictive value, 45.83% sensitivity, and 68.7% specificity for SARS-CoV-2 infection. ConclusionsSmell and taste disorders are frequent symptoms of SARS-CoV-2 infection, but not a significant predictor of the disease, as compared to the molecular RT-PCR test.