COVID-19 symptoms and duration of direct antigen test positivity at a community testing and surveillance site, January 2021-2022
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Abstract
Importance
Characterizing clinical symptoms and evolution of community-based SARS Co-V-2 infections can inform health practitioners and public health officials in a rapidly changing landscape of population immunity and viral variants.
Objective
To characterize COVID-19 symptoms during the Omicron period compared to pre-Delta and Delta variant periods and assess the duration of COVID-19 BinaxNOW rapid antigen test positivity during the Omicron variant surge.
Design, Setting, and Participants
This public health surveillance study was undertaken between January 2021-January 2022, at a walk-up community COVID-19 testing site in San Francisco, California. Testing with BinaxNOW rapid antigen tests was available regardless of age, vaccine status, or symptoms throughout.
Main Outcomes and Measures
We characterized the prevalence of specific symptoms for people with a positive BinaxNOW test during the Omicron period and compared it to the pre-Delta and Delta periods. During the Omicron period, we examined differences in symptoms by age and vaccine status. Among people returning for repeat testing during Omicron period, we estimated the proportion with a positive BinaxNOW antigen test between 4-14 days from symptom onset or since first positive test if asymptomatic.
Results
Of 63,277 persons tested, 18,301 (30%) reported symptoms and 4,568 (25%) tested positive for COVID-19. During the Omicron period, 41.6% (3032/7283) of symptomatic testers tested positive, and the proportion reporting cough (67.4%) and sore throat (43.4%) was higher than during Delta and pre-Delta periods. Congestion was higher during Omicron (38.8%) than during the pre-Delta period and loss of taste/smell (5.3%) and fever (30.4%) were less common. Fevers and myalgias were less common among persons who had received boosters compared to unvaccinated people or those who received the primary series. Five days after symptom onset, 31.1% of people with COVID-19 stated their symptoms were similar or worsening. An estimated 80.2% of symptomatic re-testers remained positive five days after symptom onset and 60.5% after ten days.
Conclusions and Relevance
COVID-19 upper respiratory tract symptoms were more commonly reported during the Omicron period compared to pre-Delta and Delta periods, with differences by vaccination status. Antigen test positivity remained high after 5 days, supporting guidelines requiring a negative test to shorten the isolation period.
Key points
Question
During the Omicron period, are there differences in COVID-19 symptomatology compared to the pre-Delta and Delta periods and how long do rapid antigen tests remain positive?
Findings
In this community-based surveillance study we detected differences in symptomatology between the Omicron period and prior variant-periods, and by age and vaccination status. Five days after symptom onset, 80% remained positive with a BinaxNOW test.
Meaning
During the Omicron period, differences in symptomatology may be due to rising population immunity and a new variant. BinaxNOW positivity remained high among re-testers, which supports guidelines that use rapid tests to shorten the isolation period.
Article activity feed
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SciScore for 10.1101/2022.05.19.22274968: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: Ethics statement: The study was conducted under a public health surveillance program that was reviewed by the UCSF Committee on Human Research and determined to be exempt and waived from IRB oversight.
Consent: All participants provided informed consent in their preferred language prior to survey administration and COVID-19 testing.Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We …SciScore for 10.1101/2022.05.19.22274968: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: Ethics statement: The study was conducted under a public health surveillance program that was reviewed by the UCSF Committee on Human Research and determined to be exempt and waived from IRB oversight.
Consent: All participants provided informed consent in their preferred language prior to survey administration and COVID-19 testing.Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Table 2: Resources
No key resources detected.
Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).
Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:Our study had certain limitations. Although it was cross-sectional, our data provide an important synthesis of symptomatology within a diverse population of people seeking community testing. Second, symptoms and timing of onset were self-reported which, may introduce bias; however, symptom data were collected prior to persons knowing their COVID-19 test result and thus would not be expected to result in differential bias between those who were COVID-19 positive and negative. Additionally, we did not characterize the severity of COVID-19 symptoms across waves, and even a single very severe symptom can cause substantially greater morbidity in an individual than multiple mild symptoms. Finally, testing was undertaken with rapid antigen tests, and thus may have resulted in misclassification of individuals during the earliest phases of their illness. Nonetheless, strict quality control measures were implemented to ensure accuracy of results and the use of rapid antigen tests. In summary, the clinical presentation of symptomatic persons changed over time during several COVID surges characterized by increasing population immunity and different SARS CoV-2 variants. During Omicron, when population immunity was higher, persons with symptoms often did not see improvement after 5 days and antigen tests frequently remained positive. These findings highlight the importance of work assurances to protect workers and requirements for rapid antigen testing to shorten isolation to protect the w...
Results from TrialIdentifier: No clinical trial numbers were referenced.
Results from Barzooka: We did not find any issues relating to the usage of bar graphs.
Results from JetFighter: We did not find any issues relating to colormaps.
Results from rtransparent:- Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
- Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
- No protocol registration statement was detected.
Results from scite Reference Check: We found no unreliable references.
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