Effectiveness of two and three mRNA COVID‐19 vaccine doses against Omicron‐ and Delta‐Related outpatient illness among adults, October 2021–February 2022
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Abstract
Background
We estimated SARS‐CoV‐2 Delta‐ and Omicron‐specific effectiveness of two and three mRNA COVID‐19 vaccine doses in adults against symptomatic illness in US outpatient settings.
Methods
Between October 1, 2021, and February 12, 2022, research staff consented and enrolled eligible participants who had fever, cough, or loss of taste or smell and sought outpatient medical care or clinical SARS‐CoV‐2 testing within 10 days of illness onset. Using the test‐negative design, we compared the odds of receiving two or three mRNA COVID‐19 vaccine doses among SARS‐CoV‐2 cases versus controls using logistic regression. Regression models were adjusted for study site, age, onset week, and prior SARS‐CoV‐2 infection. Vaccine effectiveness (VE) was calculated as (1 − adjusted odds ratio) × 100%.
Results
Among 3847 participants included for analysis, 574 (32%) of 1775 tested positive for SARS‐CoV‐2 during the Delta predominant period and 1006 (56%) of 1794 participants tested positive during the Omicron predominant period. When Delta predominated, VE against symptomatic illness in outpatient settings was 63% (95% CI: 51% to 72%) among mRNA two‐dose recipients and 96% (95% CI: 93% to 98%) for three‐dose recipients. When Omicron predominated, VE was 21% (95% CI: −6% to 41%) among two‐dose recipients and 62% (95% CI: 48% to 72%) among three‐dose recipients.
Conclusions
In this adult population, three mRNA COVID‐19 vaccine doses provided substantial protection against symptomatic illness in outpatient settings when the Omicron variant became the predominant cause of COVID‐19 in the United States. These findings support the recommendation for a third mRNA COVID‐19 vaccine dose.
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SciScore for 10.1101/2022.04.06.22273535: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: This activity was reviewed and approved by the CDC and each US Flu VE Network site’s Institutional Review Board. Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Table 2: Resources
Software and Algorithms Sentences Resources Research-collected SARS-CoV-2 positive respiratory specimens with cycle threshold values <30 and stored in appropriate transport medium were prepared for sequencing using the xGen SARS-CoV-2 library preparation kit (Integrated DNA Technologies, Inc., Coralville, IA). SARS-CoV-2suggested: (Active Motif Cat# 91351, RRID:AB_2847848)Results from OddPub: We did not detect open data. We also did not detect open …
SciScore for 10.1101/2022.04.06.22273535: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics IRB: This activity was reviewed and approved by the CDC and each US Flu VE Network site’s Institutional Review Board. Sex as a biological variable not detected. Randomization not detected. Blinding not detected. Power Analysis not detected. Table 2: Resources
Software and Algorithms Sentences Resources Research-collected SARS-CoV-2 positive respiratory specimens with cycle threshold values <30 and stored in appropriate transport medium were prepared for sequencing using the xGen SARS-CoV-2 library preparation kit (Integrated DNA Technologies, Inc., Coralville, IA). SARS-CoV-2suggested: (Active Motif Cat# 91351, RRID:AB_2847848)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:This investigation is subject to at least six limitations. First, small sample sizes limited our ability to evaluate VE by certain subgroups. Differences between 2- and 3-dose mRNA VE by vaccine product, age group, and underlying medical conditions have been reported from studies including larger numbers of patients or medical encounters [3, 5, 11-15]. Second, adolescents and children were not included in this analysis due to lower proportion of enrollment than in typical influenza seasons and lower percent vaccinated. Third, because of recent authorization of a booster dose for adults, waning of 3-dose VE could not be assessed. Waning effectiveness of a booster dose against COVID-19 associated emergency department or urgent care visits has been reported elsewhere, though the study population may have differed to a certain extent from that of the US Flu VE Network [5]. Fourth, with active enrollment, persons consenting to participate may differ from all patients in ways that may affect VE estimates, such as different healthcare-seeking behaviors among vaccinated and unvaccinated persons [10]. Vaccinated SARS-CoV-2 positive participants may have been more likely than unvaccinated positive participants to participate in this study. Fifth, Delta versus Omicron misclassification among the subset of infections without sequencing results is possible. Finally, increased use of at-home testing may result in changes in healthcare seeking behavior and potential biases for VE studies, 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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