Effectiveness of COVID-19 vaccines against Omicron and Delta hospitalisation, a test negative case-control study
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Abstract
The Omicron variant has been associated with reduced vaccine effectiveness (VE) against mild disease with rapid waning. Meanwhile Omicron has also been associated with milder disease. Protection against severe disease has been substantially higher than protection against infection with previous variants. We used a test-negative case-control design to estimate VE against hospitalisation with the Omicron and Delta variants using PCR testing linked to hospital records. We investigated the impact of increasing the specificity and severity of hospitalisation definitions on VE. Among 18–64-year-olds using cases admitted via emergency care, VE after a 3rd dose peaked at 82.4% and dropped to 53.6% by 15+ weeks after the 3rd dose; using all admissions for > = 2 days stay with a respiratory code in the primary diagnostic field VE ranged from 90.9% to 67.4%; further restricting to those on oxygen/ventilated/intensive care VE ranged from 97.1% to 75.9%. Among 65+ year olds the equivalent VE estimates were 92.4% to 76.9%; 91.3% to 85.3% and 95.8% to 86.8%. Here we show that with milder Omicron disease contamination of hospitalisations with incidental cases is likely to reduce VE estimates. VE estimates increase, and waning is reduced, when specific hospitalisation definitions are used.
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SciScore for 10.1101/2022.04.01.22273281: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics not detected. 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:Other studies where VE estimates after 3 doses were over 90% have included older cohorts or have used physician manual review of medical notes to confirm the presence of severe COVID-19 symptoms.(13, 14) We only identified one study that had stratified by …
SciScore for 10.1101/2022.04.01.22273281: (What is this?)
Please note, not all rigor criteria are appropriate for all manuscripts.
Table 1: Rigor
Ethics not detected. 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:Other studies where VE estimates after 3 doses were over 90% have included older cohorts or have used physician manual review of medical notes to confirm the presence of severe COVID-19 symptoms.(13, 14) We only identified one study that had stratified by period after a booster dose – Thompson et al found VE of 91% in the first 2 months following a third dose and 78%>= 4 months after the third dose – this is similar to our findings in 18 to 64 year olds with some of the outcomes, though generally more waning than that we observed in 65+ year olds.(14) Limitations and advantages of the test negative case control design have been previously described.(8, 18, 20) One of the biggest limitations of this specific study is that in relies on hospital coded data which may have coding errors or not have interventions coded when they were used (e.g. oxygen use). A study where data are collected prospectively on cases using reporting forms or detailed case note review could avoid this misclassification bias, but is much more challenging to do with sufficiently large numbers.(21) One potential limitation for the TNCC design when looking at severe disease in controls is test sensitivity when a large proportion of those tested are truly positive. This, however, is more likely to affect Delta than Omicron analyses (as Delta is more severe) and is one of the reasons, along with study power, that in past analyses we have chosen to use all symptomatic pillar 2 controls for hospitalised COVID-19...
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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