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The early identification of patients suffering from SARS-CoV-2 infection in primary care is of outmost importance in the current pandemic. The objective of this study was to describe the clinical characteristics of primary care patients who tested positive for SARS-CoV-2. We conducted a cross-sectional study between March 24 and May 7, 2020, involving consecutive patients undergoing RT-PCR testing in two community-based laboratories in Lyon (France) for a suspicion of COVID-19. We examined the association between symptoms and a positive test using univariable and multivariable logistic regression, adjusted for clustering within laboratories, and calculated the diagnostic performance of these symptoms. Of the 1561 patients tested, 1543 patients (99%) agreed to participate. Among them, 253 were positive for SARS-CoV-2 (16%). The three most frequently reported ‘ear-nose-throat’ and non-‘ear-nose-throat’ symptoms in patients who tested positive were dry throat (42%), loss of smell (36%) and loss of taste (31%), respectively fever (58%), cough (52%) and headache (45%). In multivariable analyses, loss of taste (OR 3.8 [95% CI 3.3–4.4], p-value < 0.001), loss of smell (OR 3.0 [95% CI 1.9–4.8], p < 0.001), muscle pain (OR 1.6 [95% CI 1.2–2.0], p = 0.001) and dry nose (OR 1.3 [95% CI 1.1–1.6], p = 0.01) were significantly associated with a positive result. In contrast, sore throat (OR 0.6 [95% CI 0.4–0.8], p = 0.003), stuffy nose (OR 0.6 [95% CI 0.6–0.7], p < 0.001), diarrhea (OR 0.6 [95% CI 0.5–0.6], p < 0.001) and dyspnea (OR 0.5 [95% CI 0.3–0.7], p < 0.001) were inversely associated with a positive test. The combination of loss of taste or smell had the highest diagnostic performance (OR 6.7 [95% CI 5.9–7.5], sensitivity 44.7% [95% CI 38.4–51.0], specificity 90.8% [95% CI 89.1–92.3]). No other combination of symptoms had a higher performance. Our data could contribute to the triage and early identification of new clusters of cases.

Background: The early identification of patients suffering from SARS-CoV-2 infection in primary care is of outmost importance in the current pandemic.Aim: To gain a better understanding of the specific symptoms of SARS-CoV-2 infection in primary care.Design and setting: We conducted a cross-sectional study between March 24 and May 7, 2020, involving consecutive patients undergoing RT-PCR testing in two community-based laboratories in Lyon (France) for a suspicion of COVID-19.Methods: We examined the association between various symptoms and a positive test using univariate and multivariate logistic regression, adjusted for clustering within the laboratories.Results: Of the 1561 patients tested, 1543 agreed to participate (participation rate: 99%). Among them, 253 were positive for SARS-Cov-2 (16%). In multivariate analysis, loss of taste (OR 3.8 [95%CI 3.3-4.4], p-value<0.001), loss of smell (OR 3.0 [95%CI 1.9-4.8], p-value<0.001), muscle pain (OR 1.6 [95%CI 1.2-2.0], p-value 0.001) and dry nose (OR 1.3 [95%CI 1.1-1.6], p-value 0.01) were significantly associated with a positive result. The strength of association with taste and smell disorders was higher for symptom combinations (OR 6.5 [95%CI 3.9-10.8] for loss of taste and smell, OR 6.7 [95%CI 5.9-7.5] for loss of taste or smell). In contrast, sore throat (OR 0.6 [95%CI 0.4-0.8], p-value 0.003), stuffy nose (OR 0.7 [95%CI 0.6-0.7], p-value<0.001), diarrhea (OR 0.6 [95%CI 0.5-0.6], p-value<0.001) and dyspnea (OR 0.5 [95%CI 0.3-0.7], p-value<0.001) were inversely associated with a positive test.Conclusion: Our data could further facilitate targeted screening and contribute to the triage and early identification of new clusters of cases.

The early identification of new cases of SARS-CoV-2 infection in primary care is of outmost importance in the current pandemia. We conducted a preliminary study involving 816 primary care patients undergoing RT-PCR testing for a suspicion of COVID-19. We examined the association between smell or taste disorders and a positive SARS-CoV-2 test, and computed the performance of these symptoms in predicting a positive test. Smell or taste disorders were significantly associated with positive RT-PCR with an adjusted OR=6.3 (95%CI 5.2-7.5). Once confinement measures are lifted, our data could further inform triage and early identification of new clusters of cases through primary care.

Fragile X syndrome linked to the FRAXA locus is the most common inherited genetic disease accounting for mental retardation and is usually caused by the expansion of an unstable CGG repeat in the first exon of the FMR1 gene on the X chromosome. Despite its robustness, Southern blot is not suitable for large-scale routine screening as part of neuropediatric practice. PCR appears as an interesting alternative, and various protocols have been successfully applied to molecular screening in mentally retarded boys and girls. Unfortunately, as of this date these protocols are unable to detect the expanded allele in FRAXA females reliably, thereby failing to discriminate between fully mutated females from normal homozygotes. Therefore, we opted for an alternative approach in designing a semiquantitative PCR assay, based on the amplification of the sole wild-type allele. This method allowed us to detect the presence of one or two normal alleles with the same sizes, thereby discriminating between a FRAXA fully mutated female or a normal homozygote, respectively. A trial on 95 DNA samples from normal and mutated females demonstrated the reliability of the procedure. We believe this simple PCR assay is a powerful approach that would reduce the recourse to Southern blotting in females with mental retardation of unknown etiology.