key: cord-0898245-b69m0oau authors: Nielsen, K. J.; Vestergaard, J. M.; Schlünssen, V.; Bonde, J. P.; Kaspersen, K. A.; Biering, K.; Carstensen, O.; Greve, T.; Hansen, K. K.; Dalboge, A.; Flachs, E. M.; Jespersen, S.; Hansen, M. L.; Mikkelsen, S.; Thomsen, M. K.; Redder, J. D.; Würtz, E. T.; Ostergaard, L.; Erikstrup, C.; Kolstad, H. A. title: Day by day symptoms following positive and negative PCR tests for SARS-CoV-2 in non-hospitalized health-care workers: a 90-day follow-up study date: 2021-03-03 journal: nan DOI: 10.1101/2021.03.02.21252437 sha: 28a9b90b561393f56870ba13eaf1a99f91881383 doc_id: 898245 cord_uid: b69m0oau Background: Little is known about the long-term course of symptoms for mild coronavirus disease 2019 (COVID-19) when accounting for symptoms due to other causes. We aimed to compare symptoms day by day for non-hospitalised individuals who tested positive and negative with polymerase chain reaction for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Methods: We followed 210 test-positive and 630 individually matched test-negative healthcare workers of the Central Denmark Region up to 90 days after the test, April-June 2020. They daily reported seven COVID-19 related symptoms. Symptom courses were compared graphically and by conditional multivariable logistic regression. Results: Thirty % of test-positive and close to zero of test-negative participants reported a reduced sense of taste and smell during all 90 days of follow-up (adjusted odds ratio [aOR] 86.07, 95% CI 22.86-323). Dyspnoea was reported by an initial 20% of test-positive with a gradual decline to about 5% after 30 days without ever reaching the level of the test-negative participants (aOR 6.88, 95% CI 2.41-19.63). Cough, headache, sore throat, muscle aches, and fever were temporarily more prevalent among the test positive participants, but after 30 days, no increases were seen. Women and participants aged 45 years or older tended to be more susceptible to SARS-CoV-2 infection. Conclusion: Prevalence of long-lasting reduced sense of taste and smell is highly increased after being diagnosed with mild COVID-19. This pattern is also seen for dyspnoea at a low level but not for cough, sore throat, headache, muscle ache or pain, or fever. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has affected most countries during the last year leading to the coronavirus disease 2019 (COVID-19) pandemic. 1 The clinical manifestations of acute SARS-CoV-2 infection range from asymptomatic, over mild symptoms to life-threatening infection with compromised respiratory capacity and organ failure. Most patients hospitalised with COVID-19 present fatigue, fever, cough, dyspnoea, musculoskeletal pain, headache, and reduced sense of taste and smell. 2,3 A high proportion still have symptoms, particularly fatigue, anosmia, sleep difficulties, and musculoskeletal pain after recovery. [4] [5] [6] There is increasing concern about the long-term consequences and a post-COVID-19 syndrome is being discussed. [7] [8] [9] Uncontrolled data from the general population and non-hospitalised COVID-19 patients with mild disease indicate that a high proportion suffer from SARS-CoV-2 related symptoms several weeks after diagnosis. [10] [11] [12] [13] [14] [15] Prospective follow-up studies of non-hospitalised COVID-19 patients including a reference group accounting for symptoms not attributable to SARS-CoV-2 are warranted. 16 The few studies comparing symptom courses of test positive with test negative non-hospitalised participants show increased occurrence of reduced sense of taste and smell and several other symptoms that persist for several weeks and months after a positive SARS-CoV-2 test. 17, 18 We aimed to compare day by day symptoms of SARS-CoV-2 PCR test-positive and test-negative non-hospitalised health-care workers up to 90 days after the test. Statens Serum Institut, with detection of the E-gene, both in-house PCRs in accordance with the Charité protocol recommended by the WHO. 21,22 Automated RNA extraction was performed at both facilities. Internal negative and positive controls were included in both the RNA extraction step and in the reverse transcription PCR step. After giving informed consent, participants received a short baseline questionnaire and then a short text message on their mobile phone or by e-mail every day at 3:30 pm linking to a questionnaire regarding the presence (yes, no) of the following symptoms within the previous 24 hours: cough, sore throat, headache, fever, muscle aches and pains, dyspnoea, and reduced or lost sense of taste and smell (available in supplementary data). Participants could respond within 24 hours from receiving the message and could resume reporting if skipping one or more days. Smoking status was collected in the baseline questionnaire. Information on occupation, sex, and age was provided by the business intelligence institution of the Central Denmark Region. We followed participants from the date of the first completed questionnaire after the first positive test, else from the first negative test until the date of the last questionnaire, 90 days after being tested, or June 30, whichever came first. No participants had a positive test after a negative test during the follow-up period. Because the indication for being tested, testing rate, and infection rate in the study population changed rapidly over time (Supplementary Figure S1 ) we for each participant tested positive, All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted March 3, 2021. ; https://doi.org/10.1101/2021.03.02.21252437 doi: medRxiv preprint randomly selected three referents with replacement among participants tested negative matching on sex and testing date (+/-2 days). The three-fold number of referents was defined by the maximum allowed within the narrowest strata. When selecting referents, we avoided crossing the specific dates where indications for being tested changed as specified above. For test-positive and test-negative participants, we computed the prevalence of the seven symptoms as well as any of the symptoms for each day of follow-up. We plotted the prevalences and smoothed the curves with local three-degree polynomial kernels. Standard error based 95% confidence intervals (95% CI) were obtained based on 100 bootstrap samples, resampling among the test-positive participants and repeating the matching of testnegative participants and the smoothing procedure. We estimated odds ratios (OR) of any symptom and the seven specific symptoms by test result (positive, negative) for three time periods (0-30, 31-60, 61-90 days) since the test by conditional logistic regression matched by sex and testing date as specified above. We assessed if sex modified the symptom prevalence among test-positive relative to test-negative participants by including an interaction term between test result and sex (man, woman). We also assessed the possible modifying effect of age (<45, ≥45 years, the median age) and testing date (≤April 7, >April 7, the median testing date) similarly. We assessed selection bias, i.e. if test-positive and test-negative participants' responding on the questionnaire on a given day were modified by the presence of symptoms the previous day, in a model that included test result, any symptom (present, absent), the interaction term between the two, and responding on the questionnaire (yes, no). The conditional logistic regression models were adjusted for age (<30, 30-39, 40-49, 50-59, and ≥60 years), except analyses of effect modification by age, occupation (nursing staff, medical doctors, biomedical laboratory scientists, medical secretaries, and other), smoking (current, previous, and never), unless else All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The nursing staff was relatively more prevalent compared to other occupations (administrative, service, and technical staff, social workers, and other less prevalent occupations) with limited patient contact among the test-positive participants. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. During the first days after being tested, about 80% of the test-positive and 75% of the testnegative participants reported at least one of the seven symptoms (figure 1). Ninety days later, these prevalences had gradually declined to about 40% and 10%, respectively. This corresponded with four-fold increased odds ratios for the complete follow-up period (adjusted odds ratio [aOR] 3.79, 95% CI 2.54-5.66) and for each of the three periods since testing (table 2) . Reduced or lost sense of taste and smell was consistently reported by 30% of the test-positive participants, except for a somewhat higher level during the initial days (figure 1). Almost none of the test-negative participants reported these symptoms. The odds ratio tended to increase by time since testing and the overall estimate was 80-fold increased (aOR 86.07, 95% CI 22.86-323, table 2). Dyspnoea was reported by an initial 20% of test-positive participants and declined gradually to about 5% after 30 days without ever reaching the level of the test-negative participants (figure 1). During the first 30 days of follow-up, the odds ratio was 11-fold increased (aOR 10.93, 95% CI 2.29-52.10) compared to test-negative participants. This ratio was reduced during subsequent days and an overall adjusted odds ratio of 6.88 (95% CI 2.41-19.63) was observed. Half of the test-positive and 15% of the testnegative participants reported cough during the initial days (figure 1). The adjusted odds ratio for the first 30 days was 2.19 (95% CI 1.10-4.37). After 30 days, no difference between the two test results was observed. At the time of the test, sore throat, muscle aches or pain, and fever were reported by 35%, 30%, and 20% of the test-positive and this was slightly more than among the test-negative participants. No differences were indicated for these symptoms after 30 days of follow-up. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. Test-positive participants aged 45 years or older showed an overall five-fold increased odds ratio (aOR 5.37, 95% CI 2.84-10.14) of any symptom compared with same-age test-negative participants (table 3) . The corresponding odds ratio obtained among participants <45 years of age was 2.43, (95% CI 1.42-4.16) and the P-value of the interaction term was 0.07. Similar patterns were seen for day 31-60 and day 61-90, but not for day 0-30. When breaking this analysis down by the seven symptoms, it appeared that this effect modification by age was primarily seen for reduced or lost sense of taste and smell and headache more than 30 days after the test (Supplementary Table S1 ). Women who tested positive reported any symptom more often than women who tested negative (aOR 4.38, 95% CI 2.90-6.60) while this was not the case for men (aOR 1.44, 95% CI 0.48-4.36, table 3) and the P-value of the interaction term was 0.05. A similar pattern was seen for day 30-60 and day 61-90 but not for day 0-30. After day 30, much higher prevalences of reduced sense of taste and smell were seen for test-positive relative to test-negative women than for test-positive relative to test-negative men (Supplementary table S2). A similar pattern was suggested for dyspnoea but at a lower level. Early vs late testing date (≤April 7 vs >April 7) did not modify the association between a positive test and any symptom (table 3) . Among study participants reporting any symptom the previous day, those who tested positive did not respond more often on the present-day questionnaire than those tested negative (aOR 0.93, 95% CI 0.75-1.15, table 4). This was also the case among participants reporting no symptoms the previous day (aOR 1.15, 95% CI 0.88-1.51). The P value of the interaction term was 0.19 and indicated that responding to the questionnaire did not depend on the presence of symptoms the previous day and test result. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted March 3, 2021. Women, middle-aged employees, and nursing staff were more prevalent in the study population than in the source population (Supplementary table S3 ). Nearly one-third of SARS-Cov-2 test-positive and close to zero of test-negative participants reported reduced sense of taste and smell during all 90 days of follow-up. Dyspnoea was reported by an initial 20% of test-positive participants and declined gradually to about 5% after 30 days without ever reaching the level of the test-negative participants. Cough, headache, sore throat, muscle aches, and fever were temporarily higher among the test positive participants, but after 30 days, no increases were seen. Women tended to be more susceptible to reduced sense of taste and smell and dyspnoea, and participants aged 45 years or older to reduced sense of taste and smell and headache beyond 30 days. The major limitation is the study participants' awareness of their test results before reporting symptoms, which is expected to have inflated reporting among the test-positive participants. Such an effect is probably strongest for loss of sense of taste and smell that has contracted public awareness worldwide and nationally. 23,24 Another limitation is only few observations during the first weeks after the test. Hereby the study primarily addresses the course of symptoms after the initial acute phase of the infection. The prospective design with daily collection of symptom reports that provides information with high temporal resolution is a major strength and makes us able to depict the courses of symptoms day by day. Another strength is the inclusion of a reference group of test-negative All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted March 3, 2021. ; https://doi.org/10.1101/2021.03.02.21252437 doi: medRxiv preprint participants recruited within the same population as the test-positive health-care workers and tested with the same kit at the same time. This allows us to take symptoms among the testpositive participants not attributed to SARS-CoV-2 infection into consideration and also to account for rapid changes in indications for testing, infection rate, and testing rate in the population. Matching on sex and adjustment for age, smoking, and occupation is expected to have further reduced potential confounding. Indication for a SARS-CoV-2 PCR-test, testing and infection rates changed during the course of the study, and for that reason, we matched participants individually on testing date. We observed no difference in the association between the test result and any symptom among participants tested early vs late during spring 2020, indicating that matching had fulfilled the purpose. We observed no indications that responding to the questionnaire on a given day depended on test results and symptoms the previous day, and this indicates no differential attrition. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. Comparison with other studies Our finding of a highly and constantly increased prevalence of reduced or lost sense of taste and smell among the SARS-CoV-2 test-positive compared with the test-negative participants is partly in accordance with two recent reports from general population samples in Israel and the US including few or no participants hospitalised for COVID-19. 18 Both studies showed initial prevalences among the test-positive participants comparable with ours, but prevalences declined to about 5% after 20 days and to 14% after 90 days, respectively. In both studies, symptom prevalences of lost sense of taste and smell among test-negative participants were constantly close to zero during follow-up in line with our findings. High initial prevalences of altered sense of smell and taste of 60-90% followed by steep recovery rates of 41-87% during 30 days of follow-up have been reported in non-hospitalised patient series. 12,13 Similar findings were also seen in a follow-up study of mainly COVID-19 outpatients examined with olfactory and gustatory psychophysical tests. 26 The first days after the test, 85% had taste and smell dysfunction, which gradually declined to 7% 60 days later. A five-fold increased prevalence of dyspnoea among test-positive compared with testnegative participants (16% vs 3%) 90 days after the test has been reported and is in line with our findings but at a higher absolute level. 18 Others have reported a constant level of dyspnoea of 30% among test-positive participants during 14-21 days of follow-up in a study that included no reference group, as well as minor difference between test-positive and testnegative participants during 20 days of follow-up. 10, 17 Increased prevalences of cough, sore throat, body aches, and fever among test-positive relative to test-negative individuals 90 days after the test, 18 high prevalences of the same symptoms among test-positive individuals 14-21 days after the test, 10 as well as no relative symptom increase in test-positive individuals 20 days after the test, have been reported. 19 The All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted March 3, 2021. ; https://doi.org/10.1101/2021.03.02.21252437 doi: medRxiv preprint latter finding being in line with ours. It should be stressed that our study accounted for the testing date, and this may explain some of the inconsistencies between earlier findings and ours. 17, 18 Our data suggest that women and older individuals are more susceptible than men and younger individuals to suffer from COVID-19 related symptoms. There is ample evidence of men being more severely affected by COVID-19 than women, and our contradictory findings may point towards explanations other than SARS-CoV-2 infection per se. 27 We observe a highly increased prevalence of long-lasting reduced or lost sense of taste and smell among participants diagnosed with mild COVID-19. This pattern is also seen for dyspnoea at a low level but not for cough, sore throat, headache, muscle ache or pain, or fever. Women and participants aged 45 years or older tend to be more susceptible to SARS- The data underlying this article will be shared on reasonable request to the corresponding author. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. None declared All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted March 3, 2021. ; https://doi.org/10.1101/2021.03.02.21252437 doi: medRxiv preprint All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. a n represents number of responses stating the presence of the specified symptom within the last 24 hours and % represents the proportion of all responses. b Adjusted odds ratios with 95% confidence intervals (CI) are obtained from conditional logistic regression models with 1:3 matching of test-positive with test-negative participants on testing date (+/-2 days) and sex (man, woman). Models are adjusted for age (<30, 30-39, 40-49, 50-59, and ≥60 years), smoking (current, previous, and never), and occupation (nursing staff, medical doctors, biomedical laboratory scientists, medical secretaries, and other), except for analyses of reduced or lost sense of taste and smell and fever due to unstable estimates that did not provide valid confidence intervals by bootstrapping. Adjusted odds ratios for day 0-90 were furthermore adjusted by time since the test (day 0-30, 31-60, and 61-90). The conditional logistic regression models provide instantaneous odds ratios that cannot be estimated from the period cumulative numbers and percentages of the table. Contents Figure S1 : Weekly SARS-CoV-2 PCR tests and daily questionnaire responses …………………………………...……. 2 (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted March 3, 2021. ; https://doi.org/10.1101/2021.03.02.21252437 doi: medRxiv preprint Figure S1 . Weekly SARS-CoV-2 PCR tests and daily questionnaire responses by week 11-27, 2020, for 210 SARS-CoV-2 test-positive and 3417 test-negative participants All rights reserved. No reuse allowed without permission. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. n represents number of responses stating the presence of the specified symptom within the last 24 hours and % represents the proportion of all responses. Adjusted odds ratios are obtained from conditional logistic regression models with 1:3 matching of test-positive with test-negative participants on testing date (+/-2 days) and sex (man, woman). Models include age (<45 years, ≥45 years), test result (positive, negative), and the interaction term between test result and age. Models provide instantaneous odds ratios that cannot be estimated from the period cumulative numbers and percentages of the table. Confidence intervals (CI) are obtained by bootstrapping. The p value is the p value of the interaction term between test result and age. Upper confidence intervals > 1000 are classified as infinity. 29 (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review) is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. The copyright holder for this preprint this version posted March 3, 2021. ; https://doi.org/10.1101/2021.03.02.21252437 doi: medRxiv preprint European Centre for Disease Prevention and Control. COVID-19 situation update worldwide, as of 12 Clinical Characteristics of Coronavirus Disease 2019 in China Features of 20 133 UK patients in hospital with covid-19 using the ISARIC WHO Clinical Characterisation Protocol: prospective observational cohort study Persistent Symptoms in Patients After Acute COVID-19 Multi-organ impairment in low-risk individuals with long 6-month consequences of COVID-19 in patients discharged from hospital: a cohort study The lasting misery of coronavirus long-haulers Long-term Health Consequences of COVID-19 b Final study population including 210 SARS-CoV-2 test-positive participants and 630 3:1 sex and testing date