Observational studyScientific reports2022
COVID-19 due to the B.1.617.2 (Delta) variant compared to B.1.1.7 (Alpha) variant of SARS-CoV-2: a prospective observational cohort study.
Observational study in Scientific reports, 2022. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 34 papers, 1 of them a synthesis that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
34 citing papers in PubMed, 1 synthesis or guideline pooled it, 67 citations in OpenAlex.
- Headaches and facial pain attributed to SARS-CoV-2 infection and vaccination: a systematic review.European journal of neurology · 2024Pooled it
- Impact of vitamin D supplementation on the clinical outcomes of COVID-19 pneumonia patients: a single-center randomized controlled trial.BMC complementary medicine and therapies · 2024Trial
- Considerations for epidemiological studies investigating emerging post-acute infection syndromes: Long Covid as a case study.EClinicalMedicine · 2026Review
- A tale of SARS-CoV-2 genomic surveillance in Mali: Variants introductions and transmission dynamics.PloS one · 2026Article
- Diversity and clinical correlations of SARS-CoV-2 variant during the introduction of the Delta variant in Guatemala.Access microbiology · 2026Article
- New-Onset Headache After SARS-CoV-2 Infection and Vaccination: Results From Three Population-Based Cohorts in Norway.European journal of neurology · 2025Article
- Impact of COVID-19 infection on genitourinary cancer management. SOGUG-COVID-19: A spanish, multicenter, observational study.Clinical & translational oncology : official publication of the Federation of Spanish Oncology Societies and of the National Cancer Institute of Mexico · 2025Observational
- Persistent mortality in critical COVID-19 ICU cases from wild-type to delta variant: A descriptive cohort study.Scientific reports · 2025Observational
- Rapid SARS-CoV-2 surveillance using clinical, pooled, or wastewater sequence as a sensor for population change.Genome research · 2024Article
- Symptoms before and after COVID-19: a population and case-control study using prospective data.The European respiratory journal · 2024Article
- Review
- Dynamic SARS-CoV-2 surveillance model combining seroprevalence and wastewater concentrations for post-vaccine disease burden estimates.Communications medicine · 2024Article
- Extracellular Vesicles: The Invisible Heroes and Villains of COVID-19 Central Neuropathology.Advanced science (Weinheim, Baden-Wurttemberg, Germany) · 2024Review
- Amino Acid Metabolism in Leukocytes Showing In Vitro IgG Memory from SARS-CoV2-Infected Patients.Diseases (Basel, Switzerland) · 2024Review
- Article
- Article
- Regional and temporal variations in COVID-19 cases and deaths in Ethiopia: Lessons learned from the COVID-19 enhanced surveillance and response.PLOS global public health · 2024Article
- Spatiotemporal evolution of SARS-CoV-2 in the Bangkok metropolitan region, Thailand, 2020-2022: implications for future outbreak preparedness.Microbial genomics · 2023Article
- Wastewater and seroprevalence for pandemic preparedness: variant analysis, vaccination effect, and hospitalization forecasting for SARS-CoV-2, in Jefferson County, Kentucky.medRxiv : the preprint server for health sciences · 2023Article
- Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
22 authors at 20 institutions in 1 country.
Funding
Abstract
The Delta (B.1.617.2) variant was the predominant UK circulating SARS-CoV-2 strain between May and December 2021. How Delta infection compares with previous variants is unknown. This prospective observational cohort study assessed symptomatic adults participating in the app-based COVID Symptom Study who tested positive for SARS-CoV-2 from May 26 to July 1, 2021 (Delta overwhelmingly the predominant circulating UK variant), compared (1:1, age- and sex-matched) with individuals presenting from December 28, 2020 to May 6, 2021 (Alpha (B.1.1.7) the predominant variant). We assessed illness (symptoms, duration, presentation to hospital) during Alpha- and Delta-predominant timeframes; and transmission, reinfection, and vaccine effectiveness during the Delta-predominant period. 3581 individuals (aged 18 to 100 years) from each timeframe were assessed. The seven most frequent symptoms were common to both variants. Within the first 28 days of illness, some symptoms were more common with Delta versus Alpha infection (including fever, sore throat, and headache) and some vice versa (dyspnoea). Symptom burden in the first week was higher with Delta versus Alpha infection; however, the odds of any given symptom lasting ≥ 7 days was either lower or unchanged. Illness duration ≥ 28 days was lower with Delta versus Alpha infection, though unchanged in unvaccinated individuals. Hospitalisation for COVID-19 was unchanged. The Delta variant appeared more (1.49) transmissible than Alpha. Re-infections were low in all UK regions. Vaccination markedly reduced the risk of Delta infection (by 69-84%). We conclude that COVID-19 from Delta or Alpha infections is similar. The Delta variant is more transmissible than Alpha; however, current vaccines showed good efficacy against disease. This research framework can be useful for future comparisons with new emerging variants.
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Registered trials
Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.