Is loss of smell an early predictor of COVID-19 severity: a systematic review and meta-analysis

Comparative Analysis of the Clinical Presentation of Individuals Who Test Positive or Negative for SARS-CoV-2: Results from a Test Street Study

The common cold, the flu, and the 2019 coronavirus disease (COVID-19) have many symptoms in common. As such, without testing for severe-acute-respiratory-syndrome-related coronavirus 2 (SARS-CoV-2), it is difficult to conclude whether or not one is infected with SARS-CoV-2. The aim of the current study was to compare the presence and severity of COVID-19-related symptoms among those who tested positive or negative for the beta variant of SARS-CoV-2 (B.1.351) and identify the clinical presentation with the greatest likelihood of testing positive for SARS-CoV-2. n = 925 individuals that were tested for SARS-CoV-2 at Dutch mass testing sites (i.e., test streets) were invited to complete a short online survey. The presence and severity of 17 COVID-19-related symptoms were assessed. In addition, mood, health correlates, and quality of life were assessed for the week before the test. Of the sample, n = 88 tested positive and n = 837 tested negative for SARS-CoV-2. Individuals who tested positive for SARS-CoV-2 reported experiencing a significantly greater number, as well as greater overall symptom severity, compared to individuals who tested negative for SARS-CoV-2. A binary logistic regression analysis revealed that increased severity levels of congestion, coughing, shivering, or loss of smell were associated with an increase in the odds of testing positive for SARS-CoV-2, whereas an increase in the severity levels of runny nose, sore throat, or fatigue were associated with an increase in the odds of testing negative for SARS-CoV-2. No significant differences in mood or health correlates were found between those who tested positive or negative for SARS-CoV-2, except for a significantly higher stress score among those who tested negative for SARS-CoV-2. In conclusion, individuals that tested positive for SARS-CoV-2 experienced a significantly greater number and more severe COVID-19-related symptoms compared to those who tested negative for SARS-CoV-2. Experiencing shivering and loss of smell may be the best indicators for increased likelihood of testing positive for SARS-CoV-2.

Analysis and comparative evaluation of expedited programs for gene therapy products: insights from the United States, the European Union, Japan, and South Korea

Gene therapy products (GTPs) used for incurable diseases can be expedited for early commercialization to fulfill unmet needs. This study analyzed the expedited programs available for GTPs in the US, EU, Japan, and South Korea using their regulatory authorities' websites, related regulations, and documents. In total, there were five expedited programs available for GTPs in the US, four in the EU, and three in both Japan and South Korea, of which four are tailored for GTPs. These programs, sharing similar objectives, can be categorized as those expediting drug development, review, and approval. However, variations are observed in eligibility criteria, specific benefits, and post-marketing study conditions across regulatory authorities. Additionally, the criteria for orphan drug designation for a rare disease differs in prevalence thresholds, incentive offered, and marketing exclusivity period. Overall, 19 GTPs were approved-13 in the US, 14 in the EU, eight in Japan, and three in South Korea-with majority obtaining regulatory approval through at least one expedited program. Therefore, future studies can analyze whether acquiring multiple expedited programs accelerates the drug development and commercialization of GTPs compared with when only one expedited program is processed. Additionally, inter-authority scientific discussion is encouraged for harmonization of expedited program requirements.

Characterizing Risk Factors for Hospitalization and Clinical Characteristics in a Cohort of COVID-19 Patients Enrolled in the GENCOV Study

The GENCOV study aims to identify patient factors which affect COVID-19 severity and outcomes. Here, we aimed to evaluate patient characteristics, acute symptoms and their persistence, and associations with hospitalization. Participants were recruited at hospital sites across the Greater Toronto Area in Ontario, Canada. Patient-reported demographics, medical history, and COVID-19 symptoms and complications were collected through an intake survey. Regression analyses were performed to identify associations with outcomes including hospitalization and COVID-19 symptoms. In total, 966 responses were obtained from 1106 eligible participants (87% response rate) between November 2020 and May 2022. Increasing continuous age (aOR: 1.05 [95%CI: 1.01-1.08]) and BMI (aOR: 1.17 [95%CI: 1.10-1.24]), non-White/European ethnicity (aOR: 2.72 [95%CI: 1.22-6.05]), hypertension (aOR: 2.78 [95%CI: 1.22-6.34]), and infection by viral variants (aOR: 5.43 [95%CI: 1.45-20.34]) were identified as risk factors for hospitalization. Several symptoms including shortness of breath and fever were found to be more common among inpatients and tended to persist for longer durations following acute illness. Sex, age, ethnicity, BMI, vaccination status, viral strain, and underlying health conditions were associated with developing and having persistent symptoms. By improving our understanding of risk factors for severe COVID-19, our findings may guide COVID-19 patient management strategies by enabling more efficient clinical decision making.

Neurological manifestations in SARS-CoV-2 infection: A single-center cross-sectional study in Malaysia

Background

Neurological involvement associated with SARS-CoV-2 infection has been reported from different regions of the world. However, data from South East Asia are scarce. We described the neurological manifestations and their associated factors among the hospitalized COVID-19 patients from an academic tertiary hospital in Malaysia.

Methods

A cross-sectional observational study of hospitalized COVID-19 patients was conducted. The neurological manifestations were divided into the self-reported central nervous system (CNS) symptoms, stroke associated symptoms, symptoms of encephalitis or encephalopathy and specific neurological complications. Multiple logistic regression was performed using demographic and clinical variables to determine the factors associated with outcome.

Results

Of 156 hospitalized COVID-19 patients with mean age of 55.88 ± 6.11 (SD) years, 23.7% developed neurological complications, which included stroke, encephalitis and encephalopathy. Patients with neurological complications were more likely to have diabetes mellitus (p = 0.033), symptoms of stroke [limb weakness (p < 0.001), slurred speech (p < 0.001)]; and encephalitis or encephalopathy [confusion (p < 0.001), forgetfulness (p = 0.006) and seizure (p = 0.019)]. Unvaccinated patients had a 4.25-fold increased risk of having neurological complications (adjusted OR = 4.25; 95% CI: 1.02, 17.71, p = 0.047). Anosmia and dysgeusia were less associated with neurological complications (adjusted OR = 0.22; 95% CI: 0.05, 0.96, p = 0.044). The odds of neurological complications were increased by 18% in patients with leukocytosis (adjusted OR = 1.18, 95% CI: 1.003, p = 0.0460).

Conclusions

Stroke, encephalitis and encephalopathy were the common neurological complications from our study. Diabetes mellitus, presence of symptoms of stroke, symptoms of encephalitis or encephalopathy, leukocytosis, and being unvaccinated against COVID-19 were the associated risk factors of developing neurological complications.

Frequency and burden of neurological manifestations upon hospital presentation in COVID-19 patients: Findings from a large Brazilian cohort

BACKGROUND

Scientific data regarding the prevalence of COVID-19 neurological manifestations and prognosis in Latin America countries is still lacking. Therefore, the study aims to understand neurological manifestations of SARS-CoV 2 infection and outcomes in the Brazilian population.

METHODS

This study is part of the Brazilian COVID-19 Registry, a multicentric cohort, including data from 37 hospitals. For the present analysis, patients were grouped according to the presence of reported symptoms (i.e., headache; anosmia and ageusia; syncope and dizziness) vs. clinically-diagnosed neurological manifestations (clinically-defined neurological syndrome: neurological signs or diagnoses captured by clinical evaluation) and matched with patients without neurological manifestations by age, sex, number of comorbidities, hospital of admission, and whether or not patients had underlying neurological disease.

RESULTS

From 6,635 hospitalized patients with COVID-19, 30.8% presented reported neurological manifestations, 10.3% were diagnosed with a neurological syndrome and 60.1% did not show any neurological manifestations. In patients with reported symptoms, the most common ones were headache (20.7%), ageusia (11.1%) and anosmia (8.0%). In patients with neurological syndromes, acute encephalopathy was the most common diagnosis (9.7%). In the matched analysis, patients with neurological syndromes presented more cases of septic shock (17.0 vs. 13.0%, p = 0.045), intensive care unit admission (45.3 vs. 38.9%, p = 0.023), and mortality (38.7 vs. 32.6%, p = 0.026; and 39.2 vs. 30.3%, p < 0.001) when compared to controls.

CONCLUSION

COVID-19 in-hospital patients with clinically defined neurological syndromes presented a higher incidence of septic shock, ICU admission and death when compared to controls.

Olfactory dysfunction in COVID-19, new insights from a cohort of 353 patients: The ANOSVID study

Olfactory disorders (OD) pathogenesis, underlying conditions, and prognostic in coronavirus disease 2019 (COVID-19) remain partially described. ANOSVID is a retrospective study in Nord Franche-Comté Hospital (France) that included COVID-19 patients from March 1 2020 to May 31 2020. The aim was to compare COVID-19 patients with OD (OD group) and patients without OD (no-OD group). A second analysis compared patients with anosmia (high OD group) and patients with hyposmia or no OD (low or no-OD group). The OD group presented less cardiovascular and other respiratory diseases compared to the no-OD group (odds ratio [OR] = 0.536 [0.293-0.981], p = 0.041 and OR = 0.222 [0.056-0.874], p = 0.037 respectively). Moreover, history of malignancy was less present in the high OD group compared with the low or no-OD group (OR = 0.170 [0.064-0.455], p < 0.001). The main associated symptoms (OR > 5) with OD were loss of taste (OR = 24.059 [13.474-42.959], p = 0.000) and cacosmia (OR = 5.821 [2.246-15.085], p < 0.001). Most of all ORs decreased in the second analysis, especially for general, digestive, and ENT symptoms. Only two ORs increased: headache (OR = 2.697 [1.746-4.167], p < 0.001) and facial pain (OR = 2.901 [1.441-5.842], p = 0.002). The high OD group had a higher creatinine clearance CKD than the low or no-OD group (89.0 ± 21.1 vs. 81.0 ± 20.5, p = 0.040). No significant difference was found concerning the virological, radiological, and severity criteria. OD patients seem to have less comorbidity, especially better cardiovascular and renal function. Associated symptoms with OD were mostly neurological symptoms. We did not find a significant relationship between OD and less severity in COVID-19 possibly due to methodological bias.

Phantosmia May Predict Long-Term Measurable Olfactory Dysfunction After COVID-19

Objectives

Persistent olfactory dysfunction (OD) after 6 months caused by SARS‐CoV‐2 infection has been reported with a variable prevalence worldwide. This study aimed to determine the prevalence of long‐term OD and identify predisposing factors.

Methods

A prospective cohort study was conducted on 100 adults with COVID‐19. Olfactory function was assessed with the University of Pennsylvania Smell Identification Test and a symptom survey at the onset of disease and 30 days later. Patients with persistent quantitative OD at the second assessment were reevaluated after 1 year. Demographic variables, symptoms, and the degree of smell loss were analyzed.

Results

Participants included 100 patients. The mean age was 42.2 ± 15.6 years, 55 (55%) were female, and 56 (56%) were outpatients. Baseline smell loss was identified in 75/100 (75%) patients, decreasing to 39/95 (40%) after 1 month, and persisting in 29 patients after 1 year. Phantosmia at baseline was the only risk factor identified for persistent OD after 1 year (relative risk 2.51; 95% confidence interval 1.53–4.12; p < 0.001). Regardless of the outcome in smell function, a significant decline in olfaction was associated with the presence of phantosmia at 1 month (β = −12.39; 95% CI −19.82 to −4.95; p < 0.01).

Conclusions

SARS‐CoV‐2 (2019–2020 variants) produced a highly frequent OD that persisted in 29% of the patients after 1 year. The presence of phantosmia at baseline and 1 month was associated with a worse evolution, but phantosmia may interfere with the performance in an identification smell test. A longer follow‐up is required in these patients.

Level of Evidence

2 Laryngoscope, 2022

Efficacy, Immunogenicity, and Safety of COVID-19 Vaccines in Randomized Control Trials in the Pre-Delta Era: A Systematic Review and Network Meta-Analysis

The most effective method of limiting the coronavirus disease pandemic of 2019 (COVID-19) is vaccination. For the determination of the comparative efficacy and safety of COVID-19 vaccines and their platforms during the pre-Delta era, a systematic review and network meta-analysis was conducted. The MEDLINE, Embase, and MedRxiv databases were searched, and the gray literature was manually searched up to 8 July 2021. The review includes the phase II and III randomized controlled trials (RCTs) that assessed the efficacy, immunogenicity, and safety of the COVID-19 vaccines. The network meta-analysis used a Bayesian model and used the surface under the cumulative ranking to rank the comparisons between the vaccines. All included studies were quality appraised according to their design, and the heterogeneity of the analyses was assessed using I2. In terms of vaccine efficacy, the mRNA-1273 vaccine ranked the highest, and the CoronaVac vaccine ranked the lowest. The mRNA-1273 ranked the highest for neutralizing antibody responses to live SARS-CoV-2. The WIV04 vaccine was associated with the lowest incidence of both local and systemic adverse reactions. All studies except one had a low to moderate risk of bias. The mRNA platform vaccines showed higher efficacy and more adverse reactions than the other vaccines.

Clinical presentation and pulmonary function tests in post-acute COVID-19 patients

AIMS

The study analysed post-acute COVID-19 symptoms and the pulmonary function test (PFT) results in patients surviving the native strain of the virus.

METHODS

The study was prospective; the inclusion criteria were positive PCR test for SARS-CoV-2 and age 18-100. Exclusion criteria were active respiratory infection, known or suspicious pre-existing pulmonary disease, cardiac failure, recent or acute pulmonary embolism, anaemia, and neuromuscular diseases. The recruitment period was 1^st March 2020 - 25^th December 2020. The initial examination was performed 4-12 weeks after the disease onset. All subjects underwent physical examination, anamnesis, chest x-ray and PFT.

RESULTS

The study involved 785 subjects (345 male) mean age 53.8 (SD 14.6). The disease severity groups were: mild (G1), moderate (G2) and severe/critical (G3). Anosmia was present in the acute disease phase in 45.2% of G1 patients, but only in 4.5% of G3 patients. Dyspnoea occurred frequently in more severe groups (40%, 51.8% and 63.7% for G1, G2 and G3 respectively), while cough and fatigue showed no relationship to disease severity. Females were more likely to experience persistent symptoms. PFT results were significantly decreased in more severe groups compared to the mild COVID-19 patients, diffusing capacity was 86.3%, 79% and 68% of predicted values in G1, G2 and G3 respectively.

CONCLUSION

Anosmia during the acute phase was associated with mild disease, persisting dyspnoea was more frequent after more severe COVID-19. Females tended to have persisting symptoms in post-acute phase more frequently. PFT results showed decrease with disease severity.

A Systematic Review on Neurological Aspects of COVID-19: Exploring the Relationship Between COVID-19-Related Olfactory Dysfunction and Neuroinvasion

Objectives

To identify neurological aspects of Coronavirus disease 2019 (COVID-19) and to investigate COVID-19 infected patients with and without olfactory dysfunction in relation to polymerase chain reaction (PCR) assay results for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) in the cerebrospinal fluid (CSF).

Methods

PubMed and EMBASE databases were searched until March 26, 2021, for observational studies with COVID-19 patients that had performed CSF PCR assay due to the neurologic symptom and reported anosmia status.

Results

Initially, 2,387 studies were identified;167 studies performed SARS-CoV-2 CSF PCR assay, of which our review comprised 45 observational studies that conducted CSF PCR assay for SARS-CoV-2 in 101 patients and reported anosmia status in 55 of 101 patients. Central and peripheral neurological manifestations observed in COVID-19 patients were diverse. The most common neurological diagnoses were Guillain-Barré syndrome (GBS) and its variants (24%), followed by encephalopathy (21%). The SARS-CoV-2 PCR assay was positive in only four CSF samples, of which two patients had olfactory dysfunction while the others did not.

Conclusions

The neurological spectrum of COVID-19 is diverse, and direct neuroinvasion of SARS-CoV-2 is rare. The neuroprotection against SARS-CoV-2 in COVID-19 patients with anosmia is controversial, as an equal number of patients with and without olfactory dysfunction had positive CSF PCR results for SARS-CoV-2 in our study, and further studies are required to provide more insight into this topic.

The Prevalence and Implications of Olfactory/Gustatory Dysfunctions among Adult COVID-19 Patients: A Retrospective Cohort Multiethnic Populations Study

(1) Background: Olfactory and gustatory dysfunctions (OGDs) was found in COVID-19 patients. Only a few studies looked into the prevalence of OGDs in the United Arab Emirates (UAE). The purpose of this study was to estimate the prevalence OGDs among multiethnic COVID-19 patients in the UAE, and its association to patients’ characteristics and disease outcomes; (2) Methods: There were 1785 COVID-19 patients included in our cohort; (3) Results: Males made up most of the study participants (86.3%). A total of 11.7% of the participants reported OGDs. Female gender and ethnicity had significantly higher symptom prevalence (p < 0.001). COVID-19 severity had a strong inverse association with OGDs (p = 0.007). Other illness outcomes, such as ICU admission, pneumonia development, and mortality, showed no correlation. Males, Asians, and patients with comorbidities all had statistically significantly lower prevalence odds. On the other hand, Emirati, Arab, and Iranian patients had a higher prevalence. COVID-19 patients with OGDs had a considerably shorter time until viral clearance than those without the symptom; (4) Conclusions: in nonsevere COVID-19, olfactory/gustatory dysfunction is common. As a result, it could be applied as a predictive sign for early disease diagnosis and prognosis.

Analysis of GMP for marketing authorization of ATMPs: comparison in the US, the EU, Japan and South Korea

Aim: This study compared regulatory systems of competent authorities related to GMP for marketing authorization of advanced therapy medicinal products (ATMPs). Methods: Dossiers for GMP and regulations and guidelines for facilities and equipment were analyzed using gap analysis. The risk-based approach (RBA) and GMP inspection were evaluated with regulations and guidelines. Results: The dossier was similar for the competent authorities. However, whereas a site master file is required in the EU, Japan and South Korea, the US requires only a biologics license application. The regulations and guidelines of facilities and equipment emphasized preventing contamination. There are differences among the competent authorities in GMP inspection and RBAs. Conclusion: Differences among the competent authorities in the marketing authorization process related to GMP for ATMPs should be considered.

Trends in Ambulatory Analgesic Usage after Myocardial Infarction: A Nationwide Cross-Sectional Study of Real-World Data

Although current guidelines for myocardial infarction (MI) recommend caution in using non-steroidal anti-inflammatory drugs (NSAIDs), real-world studies of ambulatory settings are rare. This study aimed to explore the patterns and trends of analgesic prescriptions (especially NSAIDs) among patients with a history of MI in ambulatory care settings in Korea. We analyzed real-world data from the Korea National Health Insurance Service database. Patients aged 20 years or older hospitalized with incident MI were identified between January 2007 and December 2015. Ambulatory analgesics were administered after discharge from incident hospitalization for MI, and annual trends in the prescriptions of individual analgesics were evaluated. Among the 93,597 patients with incident MI, 75,131 (80.3%) received a total of 2,081,705 ambulatory analgesic prescriptions. Prescriptions were mainly issued at primary care clinics (80.3%). Analgesics were most frequently prescribed for musculoskeletal diseases (often NSAIDs, 70.7%); aceclofenac (13.7%) and diclofenac injection (9.4%) were the frequently used NSAIDs. Additionally, significant changes were observed in the trends for some analgesics, such as loxoprofen. This study suggested that NSAIDs are commonly prescribed to patients with a history of MI. Future real-world studies are needed to elucidate the drug–disease interactions of NSAIDs prescribed after MI, especially for patients with musculoskeletal diseases.

Neurological consequences of COVID-19 and brain related pathogenic mechanisms: A new challenge for neuroscience

Due to the infection by the SARS-CoV-2 virus (COVID-19) there were also reported neurological symptoms, being the most frequent and best cited those that affect the cerebrovascular, sensorial, cognitive and motor functions, together with the neurological diffuse symptoms as for examples headache or dizziness. Besides, some of them behave high risk of mortality. Consequently, it is crucial to elucidate the mechanisms of action in brain of SARS-CoV-2 virus in order to create new therapeutic targets to fight against this new disease. Since now the mechanisms of arrival to the brain seems to be related with the following processes: blood brain barrier (BBB) disruption together with nervous or axonal transport of the virus by the trigeminal nerve, the vagus nerve, or the brain-gut-axis. Being two the mechanisms of brain affectation most cited: a direct affectation of the virus in the brain through neuroinvasion and an indirect mechanism of action due to the effects of the systemic infection. Both processes include the triggering of inflammation, hypoxia and the increased likelihood of secondary infections. This topic supposes a major novel challenge for neuroscience. Therefore, the aim of this review is to provide summarized information about the neurological symptomatology and the brain pathogenic mechanisms involved and reported in COVID-19.

Chemosensory deficits are best predictor of serologic response among individuals infected with SARS-CoV-2

OBJECTIVE

Smell and taste alteration are closely linked to infection with SARS-CoV-2 and may be associated with a more indolent disease course. Serologic response rates among individuals with mild disease remains limited. We sought to identify whether chemosensory changes associated with COVID-19 were predictive of a serologic response.

STUDY DESIGN

Cross-sectional study.

METHODS

The sample consisted of 306 adults (≥18 years old) volunteering for convalescent plasma donation following perceived COVID-19 illness from April-June 2020. Documentation of COVID-19 PCR status, clinical symptoms at time of illness, and treatment course occurred at the time of serologic analysis, where we assessed chemosensory function using patient-perceived deficits. We implemented previously validated ELISA screening to determine serologic status regarding anti-Spike immunoglobulins. Statistical analysis using stepwise logistic models were employed to identify predictive factors of serologic response.

RESULTS

Of 306 patients undergoing serologic and chemosensory evaluation, 196 (64.1%) and 195 (63.7%) reported subjective olfactory and taste dysfunction, respectively, during the first two weeks of COVID-19 infection. In unadjusted models, the odds of developing suprathreshold IgG antibody titers were 1.98 times higher among those who reported altered smell (95% CI 1.14-3.42, p = 0.014) and 2.02 times higher among those with altered taste (95% CI 1.17-3.48, p = 0.011) compared to those with normal smell and taste. Multivariable logistic models adjusting for sex, age, race/ethnicity, symptom duration, smoking status and comorbidities index demonstrated that altered smell and taste remained significant predictors of positive anti-spike IgG response (smell OR = 1.90, 95% CI 1.05-3.44, p = 0.033; taste OR = 2.01, 95% CI = 1.12-3.61, p = 0.019).

CONCLUSION

Subjective chemosensory dysfunction, as self-reported smell or taste deficiency, is highly predictive of serologic response following SARS-CoV-2 infection. This information may be useful for patient counseling. Additional longitudinal research should be performed to better understand the onset and duration of the serologic response in these patients.

The D614G Virus Mutation Enhances Anosmia in COVID-19 Patients: Evidence from a Systematic Review and Meta-analysis of Studies from South Asia

The prevalence of chemosensory dysfunction in patients with COVID-19 varies greatly between populations. It is unclear whether such differences are due to factors at the level of the human host, or at the level of the coronavirus, or both. At the host level, the entry proteins which allow virus binding and entry have variants with distinct properties, and the frequency of such variants differs between ethnicities. At the level of the virus, the D614G mutation enhances virus entry to the host cell. Since the two virus strains (D614 and G614) coexisted in the first six months of the pandemic in most populations, it has been difficult to distinguish between contributions of the virus and contributions of the host for anosmia. To answer this question, we conducted a systematic review and meta-analysis of studies in South Asian populations when either the D614 or the G614 virus was dominant. We show that populations infected predominantly with the G614 virus had a much higher prevalence of anosmia (pooled prevalence of 31.8%) compared with the same ethnic populations infected mostly with the D614 virus strain (pooled anosmia prevalence of 5.3%). We conclude that the D614G mutation is a major contributing factor that increases the prevalence of anosmia in COVID-19, and that this enhanced effect on olfaction constitutes a previously unrecognized phenotype of the D614G mutation. The new virus strains that have additional mutations on the background of the D614G mutation can be expected to cause a similarly increased prevalence of chemosensory dysfunctions.

Impairments in odour detection and hedonic ratings of unpleasant smells in asymptomatic university students as SARS-Cov-2 emerged locally

Sudden olfactory loss in the absence of concurrent nasal congestion is now a well-recognized symptom of COVID-19. We examined olfaction using standardized objective tests of odour detection, identification and hedonics collected from asymptomatic university students before and as SARS-CoV-2 emerged locally. Olfactory performance of students who were tested when the virus is known to be endemic (n = 22) was compared to students tested in the month prior to viral circulation (n = 25), a normative sample assessed during the previous 4 years (n = 272) and those tested in prior years during the same time period. Analyses showed significantly reduced odour detection for the virus exposed cohort compared to students tested before (t = 2.60; P = .01; d = 0.77; CI 0.17, 1.36) and to the normative sample (D = 0.38; P = .005). Odour identification scores were similar, but the exposed cohort rated odours as less unpleasant (P < .001, CLES = 0.77). Hyposmia increased 4.4-fold for students tested 2 weeks before school closure (N = 22) and increased 13.6-fold for students tested in the final week (N = 11). While the unavailability of COVID-19 testing is a limitation, this naturalistic study demonstrates week-by-week increase in hyposmia in asymptomatic students as a virus was circulating on campus, consistent with increasing airborne viral loads. The specific hedonic deficit in unpleasantness appraisal suggests a deficit in the TAAR olfactory receptor class, which conveys the social salience of odours. Assessment of odour detection and hedonic ratings may aid in early detection of SARS-CoV-2 exposure in asymptomatic and pre-symptomatic persons.