Demographic characteristics of SARS-CoV-2 B.1.617.2 (Delta) variant infections in Indian population
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Abstract
Importance
Higher risks of contracting infection, developing severe illness and mortality are known facts in aged and male sex if exposed to the wild type SARS-CoV-2 strains (Wuhan and B.1 strains). Now, accumulating evidence suggests greater involvement of lower age and narrowing the age and sex based differences for the severity of symptoms in infections with emerging SARS-CoV-2 variants. Delta variant (B.1.617.2) is now a globally dominant SARS-CoV-2 strain, however, current evidence on demographic characteristics for this variant are limited. Recently, delta variant caused a devastating second wave of COVID-19 in India. We performed a demographic characterization of COVID-19 cases in Indian population diagnosed with SARS-CoV-2 genomic sequencing for delta variant.
Objective
To determine demographic characteristics of delta variant in terms of age and sex, severity of the illness and mortality rate, and post-vaccination infections.
Design
A cross sectional study
Setting
Demographic characteristics, including vaccination status (for two complete doses) and severity of the illness and mortality rate, of COVID-19 cases caused by wild type strain (B.1) and delta variant (B.1.617.2) of SARS-CoV-2 in Indian population were studied.
Participants
COVID-19 cases for which SARS-CoV-2 genomic sequencing was performed and complete demographic details (age, sex, and location) were available, were included.
Exposures
SARS-CoV-2 infection with Delta (B.1.617.2) variant and wild type (B.1) strain.
Main Outcomes and Measures
The patient metadata containing details for demographic and vaccination status (two complete doses) of the COVID-19 patients with confirmed delta variant and WT (B.1) infections were analyzed [total number of cases (N) =9500, N delta =6238, N WT =3262]. Further, severity of the illness and mortality were assessed in subsets of patients. Final data were tabulated and statistically analyzed to determine age and sex based differences in chances of getting infection and the severity of illness, and post-vaccination infections were compared between wild type and delta variant strains. Graphs were plotted to visualize the trends.
Results
With delta variant, in comparison to wild type (B.1) strain, higher proportion of lower age groups, particularly <20 year (0-9 year: 4.47% vs. 2.3%, 10-19 year: 9% vs. 7%) were affected. The proportion of women contracting infection were increased (41% vs. 36%). The higher proportion of total young (0-19 year, 10% vs. 4%) (p=.017) population and young (14% vs. 3%) as well as adult (20-59 year, 75% vs. 55%) women developed symptoms/hospitalized with delta variant in comparison to B.1 infection (p< .00001). The mean age of contracting infection [Delta, men=37.9 (±17.2) year, women=36.6 (±17.6) year; B.1, men=39.6 (±16.9) year and women= 40.1 (±17.4) year (p< .001)] as well as developing symptoms/hospitalization [Delta, men=39.6(± 17.4) year, women=35.6 (±16.9) year; B.1, men=47(±18) year and women= 49.5(±20.9) year (p< .001)] was considerably lower. The total mortality was about 1.8 times higher (13% vs. 7%). Risk of death increased irrespective of the sex (Odds ratio: 3.034, 95% Confidence Interval: 1.7-5.2, p<0.001), however, increased proportion of women (32% vs. 25%) were died. Further, multiple incidences of delta infections were noted following complete vaccination.
Conclusions and Relevance
The increased involvement of young (0-19 year) and women, lower mean age for contracting infection and symptomatic illness/hospitalization, higher mortality, and frequent incidences of post-vaccination infections with delta variant compared to wild type strain raises significant epidemiological concerns.
Key Points
Question
Did SARS-CoV-2 B.1.617.2 (Delta) variant infections show varied demographic characteristics in comparison to wild type strains?
Findings
In this cross sectional study viral genomic sequences of 9500 COVID-19 patients were analyzed. As the key findings, increased involvement of young (0-19 year) and women, lower mean age for contracting infection and symptomatic illness/hospitalization, higher mortality, and frequent incidences of post-vaccination infections with delta variant in comparison to wild type (WT) strain (B.1) were observed.
Meaning
The findings of this study suggest that delta variant has varied demographic characteristics reflecting increased involvement of the young and women, and increased lethality in comparison to wild type strains.
Article activity feed
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SciScore for 10.1101/2021.09.23.21263948: (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 Any selection bias in data collection was taken care of by random sampling for the confounding factors (age, sex, date of collection, and geographical location). Blinding not detected. Power Analysis not detected. Table 2: Resources
Software and Algorithms Sentences Resources The statistical tests were performed to evaluate inter-group differences with the help of MS Excel 2019 and XLSTAT package. XLSTATsuggested: (XLSTAT, RRID:SCR_016299)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: …SciScore for 10.1101/2021.09.23.21263948: (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 Any selection bias in data collection was taken care of by random sampling for the confounding factors (age, sex, date of collection, and geographical location). Blinding not detected. Power Analysis not detected. Table 2: Resources
Software and Algorithms Sentences Resources The statistical tests were performed to evaluate inter-group differences with the help of MS Excel 2019 and XLSTAT package. XLSTATsuggested: (XLSTAT, RRID:SCR_016299)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 the study: Our study has multiple limitations, which need to be considered while interpreting the findings. Firstly, our data for reporting post-vaccination infections and patient statuses are limited, hence related observations may need further validation from the studies with larger sample size. Secondly, our data for the vaccination status details were not available in most of the accessed genomic sequence reports, hence our data for the post-vaccination infections doesn’t reflect on the prevalence of such cases in the total population. Lastly, we have not taken into account the influence of the confounding factors, such as, comorbidities, vaccination status, and previous COVID-19 infection, etc., on clinical outcomes of the studied cases, which may have influenced the quality of the results.
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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