Predictors of Severe Acute Respiratory Syndrome Coronavirus 2 Infection Following High-Risk Exposure
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Abstract
Background
Non-pharmaceutical interventions (NPIs) are recommended for COVID-19 prevention. However, the effectiveness of NPIs in preventing SARS-CoV-2 transmission remains poorly quantified.
Methods
We conducted a test-negative design case-control study enrolling cases (testing positive for SARS-CoV-2) and controls (testing negative) with molecular SARS-CoV-2 diagnostic test results reported to California Department of Public Health between 24 February–12 November, 2021. We used conditional logistic regression to estimate adjusted odds ratios (aORs) of case status among participants who reported contact with an individual known or suspected to have been infected with SARS-CoV-2 (“high-risk exposure”) ≤14 days before testing.
Results
751 of 1448 cases (52%) and 255 of 1443 controls (18%) reported high-risk exposures ≤14 days before testing. Adjusted odds of case status were 3.02-fold (95% confidence interval: 1.75–5.22) higher when high-risk exposures occurred with household members (vs. other contacts), 2.10-fold (1.05–4.21) higher when exposures occurred indoors (vs. outdoors only), and 2.15-fold (1.27–3.67) higher when exposures lasted ≥3 hours (vs. shorter durations) among unvaccinated and partially-vaccinated individuals; excess risk associated with such exposures was mitigated among fully-vaccinated individuals. Cases were less likely than controls to report mask usage during high-risk exposures (aOR = 0.50 [0.29–0.85]). The adjusted odds of case status was lower for fully-vaccinated (aOR = 0.25 [0.15–0.43]) participants compared to unvaccinated participants. Benefits of mask usage were greatest among unvaccinated and partially-vaccinated participants, and in interactions involving non-household contacts or interactions occurring without physical contact.
Conclusions
NPIs reduced the likelihood of SARS-CoV-2 infection following high-risk exposure. Vaccine effectiveness was substantial for partially and fully vaccinated persons.
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SciScore for 10.1101/2021.10.20.21265295: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics Consent: Participants were eligible to enroll if they provided informed consent in English or Spanish, and had not received a previous diagnosis of COVID-19 or positive test result for SARS-CoV-2 infection (molecular, antigen, or serological test). Sex as a biological variable not detected. Randomization Each day, interviewers called participants selected at random from all individuals with test results reported in the preceding 48 hours. 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…SciScore for 10.1101/2021.10.20.21265295: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics Consent: Participants were eligible to enroll if they provided informed consent in English or Spanish, and had not received a previous diagnosis of COVID-19 or positive test result for SARS-CoV-2 infection (molecular, antigen, or serological test). Sex as a biological variable not detected. Randomization Each day, interviewers called participants selected at random from all individuals with test results reported in the preceding 48 hours. 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:Limitations of our study included the potential for symptoms reporting to vary among participants, and the possibility that participants may have been pre-symptomatic at the time of their interview/response. In addition, bias may have occurred if individuals’ decision to wear masks was associated with their likelihood of seeking testing when asymptomatic or minimally symptomatic. Direct measurement of SARS-CoV-2 exposure intensity and clinical status was not possible under this design. However, based on our observations, real-world effects of masking and other non-pharmaceutical mitigation measures may have greater impact on individuals’ risk of infection than their likelihood of experiencing symptoms, once infected. Studies in animal models have likewise provided inconsistent support for the hypothesis that reducing SARS-CoV-2 exposure dose may lower the risk of severe disease, given infection [26]. Additional factors which may have modified the likelihood of transmission during high-risk exposure could include the vaccination status of infected contacts [30], the type of masks or face coverings used [31], the physical distance individuals maintained while interacting, and ventilation of indoor spaces where interactions occurred. Obtaining reliable information on these details of each interaction was not feasible through retrospective interviews with participants. While our sample size was under-powered to distinguish between protection associated with masking by participant...
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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