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SCENTinel 1.2 is a rapid smell test developed in the US to detect smell loss in population surveillance (Parma et al., 2021). It is composed of four subtests: odor detection, intensity, identification and hedonic range (Hunter et al., in preparation). Odor identification and hedonic evaluation of the oodors are strongly dependent on the familiarity with such odors, and as a result cultural differences are known to impact the measurement of olfactory abilities. Here, we test the accuracy of 9 versions of the rapid smell test SCENTinel 2.2 in a population of healthy adults and a group of participants with anosmia in Benin City, Nigeria. We compare their results with a group of adults from the US to identify culture-specific differences in the test response patterns. Our main aims with this preregistration are: 1. We will compare the outcome of the odor detection SCENTinel subtest separately between people with normosmia and anosmia in Nigeria. 2. We will compare the outcome of the odor intensity SCENTinel subtest separately between people with normosmia and anosmia in Nigeria. 3. We will compare the outcome of the odor identification SCENTinel subtest separately between people with normosmia and anosmia in Nigeria. 4. We will compare the outcome of the odor hedonic range SCENTinel subtest separately between people with normosmia and anosmia in Nigeria. 5. We will compare the outcome of the overall SCENTinel test separately between people with normosmia and anosmia in Nigeria. 6. We will compare the test-retest reliability to the overall SCENTinel test in people with normosmia in Nigeria. 7. We will compare the outcome of the odor detection SCENTinel subtest between people with normosmia in Nigeria and in the US. 8. We will compare the outcome of the odor intensity SCENTinel subtest between people with normosmia in Nigeria and in the US. 9. We will compare the outcome of the odor identification SCENTinel subtest between people with normosmia in Nigeria and in the US. 10. We will compare the outcome of the overall SCENTinel test between people with normosmia in Nigeria and in the US. 11. We will compare the outcome of the overall SCENTinel test between people with anosmia in Nigeria and in the US.

The purpose of this project is to validate the Social Odor Scale (SOS, Dal Bò et al., 2021) in several languages to promote its use across different countries, languages, and cultures. The SOS takes the form of a self-administered questionnaire where participants indicate their level of agreement with 12 propositions to assess one’s awareness of the social odor surroundings. Its short format makes it easy to implement in research protocols, for basic or clinical assays. It is already available in Italian and in German (Dal Bò et al., 2021, Plos One). Broadening the availability of the SOS across languages will help standardize the research procedures on body odor collection and perception across research laboratories, ultimately supporting the creation of directly comparable research results. The SOS score can help to phenotype both social odor donors and recipients based on their ability to be tuned in to body odors, and it can thus serve as correlate to the behavioral, psychophysiological, neural, and clinical data. Body odor research has been of great interest in several countries, including most prominently Italy, Germany, France, the Netherlands, Sweden, and the United States of America. Therefore, in this first standardization study, we include representatives of research groups from these countries to drive this set of translations of the SOS. The present study thus aims to validate translations of the SOS in: French, Dutch, Swedish and English, additionally to the Italian and German translation that has already been published (Dal Bò et al., 2021). In this study, we aim to determine whether the factor structure of each translation remains similar to the validated Italian version (Dal Bò et al., 2021): one higher-order factor representing social odor awareness in general and three lower-order factors representing Familiar, Partner, and Stranger social odors. In addition to evaluating the persistence of the three-factor structure of each translation, we will determine the convergent and divergent validity of the SOS. Several odor scales are already available in the literature. To test the convergent validity, we chose 1) the Body Odor Sniffing Questionnaire (BOSQ, Li et al., 2022), a 17-item questionnaire focusing on how much one smells self-private (e.g. Do you ever sniff/smell your own hands?), others’ (e.g., Do you ever sniff/smell your friends?) and self-common body odors (e.g., Do you ever smell the pillows/quilts you have- slept on?) ; and 2) the Odor Awareness Scale (Smeets et al., 2008), a 32-item questionnaire on one’s awareness of odors in general in the environment (e.g., Do you sniff at a new book?). To test the divergent validity, we chose to use the visual subscale (v) of the Sensory Sensitivity Scales (SeSS, Aykan et al., 2020) which includes among others a 10-item questionnaire addressing visual sensitivity independent of social dimensions (e.g., I feel the need to squint my eyes in bright sunlight).

The five senses are traditionally valued differently by individuals. As early as in ancient Greek society, Plato described vision and hearing as higher in the hierarchy of the senses than the so-called “bodily senses” of smell, taste, and touch (Korsmeyer, 2002; Reinarz, 2014). In modern times, the value placed on taste and smell as compared to vision and hearing does not seem to have changed. The American Medical Association Guides to Permanent Impairment (Rondinelli et al., 2008) evaluate “loss of smell” as equal to 1–5% of a person’s earnings, while loss of vision is given 85% of an individual’s worth. In some cases, taste loss is not even considered an impairment (Méntabel, Beskæftigelsesministeriet, 2017). Since the beginning of the COVID-19 pandemic, many, if not most, have been affected by sensory alterations, most prominently in taste and smell (Parma et al., 2020). This high prevalence of sensory loss in the general population, whether experienced directly or indirectly through others, may have altered the perceived value of taste and smell. (Herz & Bajec, 2022) investigated the perceived value of smell relative to hearing and vision both by asking which sense participants would rather lose and by asking whether participants would rather lose a range of commodities or one of the senses. Despite the media attention and health coverage given to the sense of smell during the initial phases of the pandemic when the survey was first deployed, the sense of smell remained undervalued as compared to hearing and vision, as well as to a series of commodities (e.g., cellphone). Yet, individual differences pertaining to gender and life stage mediate the importance of the senses and the value of the commodities tested, with women and younger adults being especially likely to give up their sense of smell in order to keep their hair or their cell phone. The present study is a conceptual replication of the survey proposed by Herz and Bajec (Herz & Bajec, 2022), characterized by three main differences: Data collection is performed in Dec 2022, much later in the COVID-19 pandemic as compared to the original survey, when a larger portion of the population has experienced chemosensory dysfunction as a result of COVID or other disorders This survey aims to explore the psychological value of the sense of taste, along with the psychological value of the sense of smell, which was unexplored in Herz and Bajec. This survey's recruitment was done all over the world and in six languages (English, French, Spanish, Arabic, Chinese, and Italian) instead of just in English and in the Boston area, as Herz and Bajec did. This was done to improve the external validity of the results.

Preparing for the pre-registration and ensuing analysis

Loss or impaired sense of smell is a symptom of viral illnesses, including the common cold (Pellegrino et al., 2017) and SARS-CoV-2 (Gerkin et al., 2020; Pellegrino et al., 2020), sinonasal disease (Dalton, 2004), traumatic brain injury (Collet et al., 2009), drugs or toxins (Schiffman, 2018; Upadhyay & Holbrook, 2004), neurodegenerative diseases (Ponsen et al., 2009; Solomon, 1994), surgery (Deems et al., 1991), and chemotherapy (Amézaga et al., 2018), among others (Nordin & Brämerson, 2008). Prior to 2020, over 200,000 people sought treatment for olfactory impairment annually (Pellegrion et al., 2020), primarily caused by viral illnesses (Dalton, 2004). COVID-19 has increased the known prevalence for post-viral smell loss by ~30% (Hummel et al., 2016), and ~20% for all forms of smell loss (Hannum et al., 2020; Liu et al., 2016; Mullol et al., 2012). However, subjective measurements may underestimate the true prevalence of smell loss by about 26% (Hannum et al., 2020) in part due to general lack of awareness of chemosensory changes in the general population. Objective measurements can more accurately identify changes in smell function, but are not always feasible due to scaling, time or budget constraints (Parma et al., 2021). Yet they represent the best way to track recovery from smell loss. A quick recovery would minimize the negative effects associated with smell loss, such as a reduced quality of life (Boesveldt et al., 2017), depression (Rochet et al., 2018), malnutrition (Gopinath et al., 2016) and exposure to toxins such as smoke and natural gas (Pence et al., 2014). However, the time to recovery is variable: 85% of people recover from post-COVID smell loss within 3 weeks (Cecchetto et al., 2021; Chiesa-Estomba et al., 2020; Reiter et al., 2020; Vaira et al., 2020), while 15% of people do not recover and their smell loss persists long after the rest of their COVID-19 symptoms subside (Borsetto et al., 2020; Cecchetto et al., 2021; Chiesa-Estomba et al., 2020; Vaira et al., 2020). Others with post-viral smell loss have reportedly taken years to recover (Lee et al., 2014). Other etiologies of smell loss may also have longer or more permanent effects on smell loss, such as traumatic brain injury (Reden et al., 2006) or neurodegenerative diseases (Hummel et al., 2016; Whitcroft et al., 2017). Recovery may also differ depending on age and sex of the person (Amer et al., 2020; Lee et al., 2014; Mullol et al., 2012). There is currently no cure for smell loss, however some interventions have been effective in improving smell recovery, such as olfactory training (Sorokowska et al., 2017) and pharmacological interventions (Hummel et al., 2016; Yan et al., 2019). Due to the rapid influx of studies assessing smell loss from COVID-19, the time is mature for a metanalytic analysis to synthesize the factors influencing recovery from post-viral smell loss, and compare it recovery following smell loss due to other etiologies (e.g. post-traumatic, neurodegenerative, sinonasal, toxins, surgery, and chemotherapy). A comprehensive analysis of recovery from smell loss due to COVID-19 and how it compares to other etiologies of smell loss does not currently exist. The aim of the study is to determine the recovery prevalence and recovery time from smell loss based on the available literature. Etiology of smell loss, time since etiological event (for prevalence), type of test (subjective vs objective), presence/absence of an intervention, type of intervention, age, and sex will be used as moderators. With this literature search and analysis, we will answer the following experimental questions if data from 4 or more articles per condition can be included: 1. What is the prevalence (percent) of smell loss recovery overall (all etiologies with minimal intervention combined)? 2. What is the prevalence (percent) of smell loss recovery from post-COVID smell loss compared to other etiologies of smell loss (if 4 or more articles are available per etiology). 3. How does the prevalence (percent) of smell loss recovery differ among etiologies of smell loss (if 4 or more articles are available per etiology). ● Exploratory analysis: How does the prevalence (percent) of smell loss recovery differ among acute (12 weeks) cases of smell loss (if >4 of each case are available). 4. Does the prevalence (percent) of smell loss recovery differ based on type of assessment (objective vs. subjective)? 5. Do certain demographics (age and sex) have a higher prevalence (percent) of smell loss recovery than others? 6. Do interventions improve smell loss recovery prevalence (percent)? 7. What is the recovery time (days) from smell loss overall (all etiologies with minimal intervention combined)? 8. What is the recovery time (days) from post-COVID smell loss compared to other etiologies of smell loss (if 4 or more articles are available per etiology). 9. How does the recovery time (days) from smell loss differ among etiologies of smell loss (if 4 or more articles are available per etiology). ● Exploratory analysis: How does the recovery time (days) from smell loss differ among acute and chronic cases of smell loss (if >4 of each case are available). 10. How does the recovery time (days) from smell loss differ based on type of assessment (objective vs. subjective)? 11. Do certain demographics (age and sex) have a reduced recovery time (days) from smell loss than others? 12. What is the impact of interventions on recovery time (days) from smell loss? Recovery includes any reported improvement in smell function.

Chemosensory loss has taken on a new meaning for people worldwide as loss of smell (and taste, as well as chemesthesis) has become a prominent symptom of COVID-19, now recognized by health authorities including the CDC. As part of an international effort to better understand this chemosensory connection to COVID-19, the GCCR questionnaire is currently implemented in 32 languages and targets people who have or recently have had an upper respiratory infection (e.g., common cold, influenza, suspected or confirmed COVID-19). The initial analyses of a subset of these data (up to April 18th) confirm substantial loss of smell, taste and moderate chemesthesis loss (e.g., the burn of chili peppers, the cooling of menthol, tingle of carbonation) in individuals with COVID-19; notably, this loss was independent of nasal obstruction. The results (Parma et al., 2020) showed largely overlapping patterns of chemosensory impairment in people with COVID-19 confirmed by laboratory tests versus those diagnosed by symptoms alone (e.g., a clinical assessment by a medical professional). After exploration of the second data tranche of the GCCR dataset up to May 14th (henceforth, May dataset), as detailed in our previous preregistration (https://osf.io/ek8jq/), we discovered that after standard cleaning procedures, we had failed to reach the minimal number of participants (N =480) per group that we had declared previously. We therefore waited additional time to reach and surpass the N = 480 threshold, while we explored the available database. With this new pre-registration, we are reporting our planned analyses of the dataset that will be downloaded on July 3rd (henceforth, July dataset) and that is hence not yet available. This new preregistration aligns with our previous one (https://osf.io/ek8jq/), therefore preserving the main goals of the study. Here, we also refine our hypotheses based on the knowledge gained during initial exploration of the May 14th dataset. Below are the major edits that we have introduced and that we intend to apply to the July dataset: Criteria to determine the C19+ and C19- groups (section 17): based on current analyses, we replicate the previously published drop in smell and taste ratings during vs. before the illness in COVID-19 (Parma et al., 2020). However, we observed small but significant differences in chemosensory ratings between the clinically assessed and the lab tested COVID-19 group. In this new preregistration, we therefore follow a more conservative approach and propose to limit analysis to the comparison of participants who reported to have received a lab test for the C19+ vs. C19- analysis. Characterization of multiple diagnostic groups based on smell ratings, as smell change is the assumed most predictive symptom differentiating COVID-19 from other respiratory illnesses: COVID-19 clinical assessment, COVID-19 positive (C19+) lab tested, COVID-19 negative (C19-) lab tested, Unknown (not diagnosed/tested, yet with symptoms). Inclusion of a new goal: exploration and prediction of post C19+ smell loss recovery. In summary, these are goals being pre-registered for investigation in the July dataset . We will determine if we can replicate the previously published results on smell, taste, chemesthesis and nasal obstruction change during COVID-19 versus before COVID-19 (Parma et al., 2020) in participants reporting clinically assessed and lab tested COVID-19 based on data collected since the first data snapshot GCCR001 collected in April 2020. We will compare chemosensory and nasal obstruction changes of the C19+ with participants reporting to have received a negative COVID-19 lab test (C19-). We will determine if a pattern of chemosensory changes, other symptoms, and/or demographics can be identified that discriminate C19+ vs. C19- We will determine if a pattern of chemosensory changes, other symptoms, and/or demographics can be identified that discriminate those with C19+ who recover from smell loss vs. those who do not within the timeframe of the survey completion.

A strict lockdown has been enforced in France for the past two months. Administratively, France is split into regions (states) and departments (counties). On Thursday, May 7th the French government will categorize each county/region according to sanitary conditions: regions where the virus circulates little and the health system is not congested will be labelled «green», otherwise «red». This will have societal and economical impacts in the labelled areas: in red areas, no school opened, restricted movement and services, but less restrictions in green areas. Today, criteria to define this future label are based solely on COVID-19 sanitary parameters. Nevertheless, COVID-19 is also characterized by clinical symptoms among which chemosensory loss is very prevalent in France, and this symptom could be of interest in predicting the future sanitary conditions of a specific area. In this report, we aim to answer four questions: Q1- Is the number of self-reported smell and/or taste change in each state (“Région”) in France correlated with parameters of overwhelmed hospitals (number of COVID-19+ cases, hospitalizations, reanimations, mortality cases due to COVID-19) in this area within the same period of time (last 3 month, around the beginning of the COVID-19 pandemic)? Q2- Is the number of people searching the internet for queries related to smell and/or taste in each state (“Région”) in France correlated with parameters of overwhelmed hospitals (number of COVID-19+ cases, hospitalizations, reanimations, mortality cases due to COVID-19) in this area within the same period of time (last 3 month)? Q3- How self-reported smell and/or taste change and/or internet for queries related to smell and/or taste during the last 3 month can be related to the future “red”/”green” status of each state/county status in France? Q4 (exploratory) - We will explore - among people who declared a change in smell/taste - how the number of first notice symptoms (related to the illness) evolve around the lockdown and how this can be used as a longitudinal (?) marker of the positive effect of containment measures? This is will be done in France and a comparable country whereby the lockdown was set earlier (Italy) or later (UK).

Individuals with underlying chronic health conditions are reported to be at increased risk for COVID-19 infection1. Obesity, in particular, is recognized as a major contributor to the severity of COVID-19 illness, especially in young adults with BMI >30 kg/m22. Despite the severity, COVID-19 symptoms have not been systematically assessed in this population group. Here we propose to systematically describe and compare the symptoms in COVID-19 in adults who self-report to be obese or non-obese. While the mechanisms linking excess body weight with COVID-19 are unclear, it is suggested that a pro-inflammatory status in obese adults may impair the adaptive immune response to influenza virus3. Another unique characteristic of COVID-19 is the loss of smell and/or taste4, now a diagnostic criterion for the illness. Interestingly, impaired smell/taste functions are commonly reported in obese adults without COVID-19, and they are attributed to their chronic inflammatory state5,6. Nonetheless, the reliability of using these chemosensory measures as a diagnostic criterion for COVID-19 illness in the obese population is unknown. This information is clinically significant as it may evaluate whether using smell screening tests is an effective diagnostic tool for obese adults. In this exploratory analysis, we will answer the following questions: Is there a difference in chemosensory perception and related symptomatology in adults with self-reported obesity vs no-obesity during the COVID-19 illness? Is the pre-COVID-19 chemosensory perception significantly different from the post-COVID-19 chemosensory perception in adults with self-reported obesity vs no-obesity? Is the post-COVID-19 chemosensory recovery different in adults with self-reported obesity vs no-obesity? Can the difference in smell ratings pre- vs post-COVID diagnosis predict COVID-19 diagnosis in adults with self-reported obesity vs no-obesity?

An online questionnaire has been globally deployed in over dozen languages to investigate the alterations in chemosensory functions in people with COVID-19. A first data analysis confirmed chemosensory impairment in patients with COVID-19 (Parma et al., 2020), however very little is known about timing, rate and modalities of recovery of the chemosensory functions, namely smell, taste and chemesthesis. The majority of anecdotal and clinical reports suggests that smell disturbances persist for approximately 1-2 weeks after the onset of the disease (Pellegrino et al., 2020). A study by Lechien et al., (2020) described that, of a total of 357 patients, 44% had a short-term recovery rate, and 72.6% showed a recovery of the olfactory functions within 8 days following the resolution of the disease. In another study (Yan et al., 2020), 74% on a total of 59 COVID-19 patients reported improvement of both olfactory dysfunction and overall illness symptoms within 2 weeks. Taste and chemesthesis recovery have been less investigated, and most of the information currently available were retrieved from Italian patients (see for example Giacomelli et al., 2020, Spinato et al 2020). However, we currently lack a large scale and detailed analyses of olfactory and taste recovery, while chemesthesis recovery have never been investigated. After China, Italy was the first country in which the COVID-19 pandemic rapidly spread. At the release of the Italian version of the online questionnaire (on April 10th), 98,275 Italians were infected (data provided by the Italian Ministry of Health) (http://www.salute.gov.it/portale/nuovocoronavirus/dettaglioContenutiNuovoCoronavirus.jsp?area=nuovoCoronavirus&id=5351&lingua=italiano&menu=vuoto). This data suggests the possibility that a high rate of data collected was from subjects in the recovery phase, which could provide valuable information on the recovery of smell/taste/chemesthesis alterations. In this study we will investigate and characterize smell, taste, and chemesthesis changes AFTER the peak of COVID-19 illness in the Italian residents, and correlate them with different features of the COVID-19 respiratory illness. In particular, we want to: - relate the chemosensory abilities and blocked nose recovery (described during the online-survey) with the onset of the respiratory illness - explore whether the degree of recovery of chemosensory abilities depends on the severity of the impairment during the respiratory illness - explore whether the results that we will find for the Italian residents can be generalize to other populations

This is the preregistration for an observational online study: the GCCR Smell-&-Taste-Check. It combines 1) an online survey with questions about demographics, health (e.g., medical history, COVID-19 status, COVID-19 symptoms), quantitative self-reported remembered ability to smell, taste, and experience oral irritation (like the burning from chili peppers) as well as the ability to breathe through the nose with 2) a practical part where participants rate the smell and taste intensity of four suggested household items/foods (e.g., the smell of shampoo or the sweetness of sugar). Participants are given visual analogue scales with anchors at both ends that produce quantitative evaluations of self-reported sensory abilities (part 1) and experienced intensity (part 2), respectively. The study was designed to provide a means to test (if used once) or monitor (if used more than once) chemosensory abilities. Here, we propose a first analysis with the aim to assess the relationship between the self-reported chemosensory abilities and the experienced chemosensory intensities.

COVID-19 is associated with notable decrements in chemosensation. Notably, other upper respiratory infections (URIs) are also associated with decrements in chemosensory ability, though their pathophysiology and extent likely differ from that of COVID-19. Here, we seek to determine whether self-reported text descriptors of chemosensory ability can predict COVID+ versus COVID- status, and then characterize the semantic architecture of these predictive features. Finally, we seek to use the text descriptors provided to better characterize qualitative loss in smell and chemesthesis. We will answer the following questions: 1. What is the sensitivity and specificity of applying natural language processing tools to self-reported text descriptors of chemosensory ability for predicting COVID+ vs. COVID-? 2. What are the characteristics of the semantic architecture of predictive self-reported text descriptions of chemosensory-related COVID+ vs COVID- diagnosis? 3. What are the qualitative characteristics of anosmia, hyposmia, parosmia, and phantosmia associated with COVID+?

This study aims at validating a novel rapid smell test to be used in the surveillance of COVID-19. The specific goals of this validations are the following: 1. Validate the accuracy of the rapid smell test against a gold-standard test, the NIH Olfactory toolbox in normosmics 2. Characterize the response patterns of individuals with pre-existing smell disorders to the rapid smell test

Anecdotal reports, several archived preprints and a few very recent peer-reviewed studies suggest that alterations in chemosensory function are common in people with COVID-19. However, the type (smell, taste, chemesthesis), severity, and quality of these alterations remains unclear. Particularly, taste and chemesthesis (i.e., chemical activation of the trigeminal, glossopharyngeal, and vagus nerves) have not yet been in the focus of investigations. Furthermore, most prior reports have been limited to single countries. To answer the following research questions we have globally deployed an online questionnaire in over a dozen languages. In this initial report, we will compare respondents from two diagnostic groups, (a) those who report that their COVID-19 diagnosis was confirmed via objective tests (henceforth “lab tested”) compared with (b) respondents who report that their COVID-19 diagnosis was obtained via clinical observation by a medical professional (henceforth, “clinical exam”). We will answer the following questions: Does the self-reported change in smell, taste or chemesthesis function (during vs. before COVID-19 disease) differ between the two diagnostic groups? Is the self-reported change in smell function associated with changes in nasal patency, and does this differ in the two diagnostic groups?

Review of the current literature of chemosensory changes during the covid-19 pandemic.

We know that studying smell and taste loss in children and adolescents may be challenging, and as a result it is an understudied phenomenon (Schriever et al., 2018) . Sudden smell and taste loss is a prominent and prevalent symptom of COVID-19 in adults, which can be harnessed for early detection of the disease and to control the spread of the infection (Gerkin et al., 2021; Menni et al., 2020).). Though it is unclear whether smell and taste loss have been harnessed as a symptom of COVID-19 in children and adolescents. With this meta-analysis, we aim to answer the following questions: 1. Are smell and taste loss a symptom assessed in relation to COVID-19 in children and adolescents? 2. If so, are subjective ratings mainly used to determine smell and taste loss? Who provides the report: children, parents, healthcare professionals? 3. Given that relying on subjective smell and taste ratings in adults with COVID-19 underrepresents the prevalence of smell and taste loss in the population (Hannum et al., 2020), can we quantify whether this happens in children and adolescents?

Adult participants rate their sense of taste and smell at home using common items each week to track changes especially after recovery from COVID-19 or other insults, e.g., or other viral infections.

Multi-lingual, international questionnaire to assess self-reported quantity and quality of perception in three distinct chemosensory modalities (smell, taste, and chemesthesis) before and during COVID-19