Simultaneously complete but not partial taste and smell losses were associated with SARS-CoV-2 infection

Abstract

Objectives: The aim of this study was to investigate the association between taste and smell losses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, and to elucidate whether taste preference influences such taste loss.

Methods: A matched case-control study was conducted in 366 Thai participants, including 122 who were confirmed SARS-CoV-2-positive by RT-PCR (case group) and 244 who were SARS-CoV-2-negative (control group). Taste, smell, and appetite changes were assessed by self-reported visual analog scale. Preference for sweet, salty, umami, sour, bitter, and spicy were judged using the validated TASTE-26 questionnaire.

Results: Partial taste and smell losses were observed in both groups, while complete losses (ageusia and anosmia) were detected only in the case group. Moreover, only ageusia and anosmia were associated with SARS-CoV-2 positivity (P < 0.001, odds ratio of 14.5 and 27.5, respectively). Taste, smell, and appetite scores were more severely reduced in the case group (P < 0.0001). Multivariate analysis showed that anosmia and ageusia were the best predictors of SARS-CoV-2 positivity, followed by appetite loss and fever. Simultaneous losses of taste and smell but not taste preferences were associated with SARS-CoV-2 positivity (P < 0.01, odds ratio 2.28).

Conclusions: Complete, but not partial, losses of taste and smell were the best predictors of SARS-CoV-2 infection. During the current COVID-19 pandemic, healthy persons with sudden simultaneous complete loss of taste and smell should be screened for COVID-19.

Keywords: Appetite; COVID-19; Case–control study; Smell; Taste; Thai.

Figure 1

Taste and smell alterations and COVID-19. Image ‘a’: the stacked bars represent the percentage of total participants in the case and control groups who had respiratory symptoms (white) or did not have symptoms but had contact with infected persons (black). P-values derived from Fisher’s exact test; *P < 0.05. OR = odd ratio. Images ‘b’ and ‘d’: the stacked bars represent the percentage of total participants in the case and control groups who had no change (white), a partial change (grey), or a complete loss (black) of taste (b) or smell (d). P-values derived from the Chi-square test; * P < 0.05, **P < 0.01. Images ‘c’ and ‘e’: the horizontal bar graphs represents the mean ± standard deviation of the change in self-reported taste (c) and smell scores (e) after COVID-19 was suspected. Negative numbers indicate the magnitude of the reduction in taste or smell perception. P-values derived from the Mann–Whitney test; **P < 0.01, ****P < 0.0001.

Figure 2

Coincidence of taste and smell loss and appetite change. Image ‘a’: The stacked bars represent the percentage of total participants in the case and control groups who had no change (white), on-and-off (light grey), distorted (dark grey), reduced (light black), or complete losses (black) of taste. P-values derived from the Chi-square test; ****P < 0.0001. Image ‘b’: The stacked bars represent the percentage of participants with taste or smell loss in the case and control groups who had taste loss before smell loss (white), smell loss before taste loss (grey), or simultaneous taste and smell loss (black). P-values derived from the Chi-square test; *P < 0.05. Image ‘c’: The stacked bars represent the percentage of participants with taste or smell loss in the case and control groups who had simultaneous (black) or not simultaneous (white) loss of taste and smell. P-values derived from Fisher’s exact test; **P < 0.01. OR = odd ratio. Image ‘d’: The stacked bars represent the percentage of participants with appetite change in the case and control groups who had moderate (grey) or severe (black) loss of appetite. P-values derived from Fisher’s exact test; **P < 0.01. OR = odd ratio.

Figure 3

Taste preference and COVID-19. Images ‘a’ to ‘f’: the stacked bars represent the percentage of the total participants in the case and control groups who had a mild (white), moderate (grey), or strong (black) preference for each taste/factor as specified in the figures (a–f). P-values derived from the Chi-square test.