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COVID-19
see COVID-19 Pandemic.
🧬 COVID-19 Variants Overview
This table summarizes the major SARS-CoV-2 variants, their characteristics, and clinical implications.
Major Variants
| Variant | First Identified | Key Features | Clinical Impact | WHO Label |
|---|---|---|---|---|
| Alpha (B.1.1.7) | UK, Sept 2020 | Highly transmissible | More severe disease | Variant of Concern |
| Beta (B.1.351) | South Africa, May 2020 | Immune escape | Possible vaccine resistance | Variant of Concern |
| Gamma (P.1) | Brazil, Nov 2020 | Reinfection risk | Moderate severity | Variant of Concern |
| Delta (B.1.617.2) | India, Oct 2020 | Very high spread | Higher hospital/death rates | Variant of Concern |
| Omicron (B.1.1.529) | Southern Africa, Nov 2021 | Extremely contagious, many mutations | Milder disease | Variant of Concern |
| Subvariant | Key Notes |
|---|---|
| BA.1 / BA.2 | Initial waves; BA.2 more transmissible |
| BA.4 / BA.5 | More immune-evasive; widespread in mid-2022 |
| XBB / XBB.1.5 (“Kraken”) | Recombinant; caused winter 2022–23 surge |
| EG.5 (“Eris”) | Circulated mid-late 2023; moderate immune escape |
| JN.1 | Dominant in early 2024 |
General Trends
- Early variants: more severe in unvaccinated
- Omicron and beyond: milder but more transmissible
- Current focus: protection of vulnerable and managing comorbidities
Cross-Sectional Studies
In a cross-sectional study Jinjing Lu *et al.* from the Shengjing Hospital, Shenyang published in BMC Medicine to assess changes in cardio-cerebrovascular risk factors (CCVRFs) across three periods—pre-, during-, and post-COVID-19 lockdown—using preventive health assessment data from a single large center. The study found a statistically significant increase in diabetes mellitus, systemic immune-inflammation indices (NLR, PLR, SII), and insulin resistance markers (TyG, TyG-BMI) during the lockdown period, with older adults (>60 years) disproportionately affected. These findings underscore the need for targeted health strategies during prolonged societal disruptions 1).
Critical Review:
Despite its large sample size (n=46,958), this study suffers from inherent limitations of its cross-sectional design—specifically, an inability to establish causality. The use of a single-center cohort from one health management center in Shenyang introduces a selection bias, as individuals undergoing routine health assessments are not representative of the general population. Furthermore, while statistical significance is claimed across various parameters, clinical significance remains unaddressed. The temporal grouping (3-year pre-pandemic vs. 3-year lockdown vs. 1-year post-lockdown) is asymmetrical, potentially skewing comparative interpretations. Regression analyses are used effectively but without adjustment for key confounders such as socioeconomic status, access to healthcare, or physical activity changes—factors known to influence CCVRFs. Overall, while the data confirms expected trends, its real-world applicability is limited due to methodological constraints.
Final Verdict:
Moderately informative but suffers from design limitations that impair clinical utility.
Takeaway for the Practicing Neurosurgeon:
Recognize the indirect cerebrovascular implications of prolonged lockdowns—particularly the increase in systemic inflammation and insulin resistance—in older populations.
Bottom Line:
A single-center, large-sample cross-sectional analysis confirms the lockdown’s adverse impact on CCVRFs, especially among the elderly, but lacks depth in causal inference and external generalizability.
Rating: 4/10
Full Citation: Lu J, Shen Y, Liu X, Mao Y, Jing L, Yang Z, Pei D, Dong W. Increased prevalence of cardio-cerebrovascular risk factors during the COVID-19 pandemic lockdown: a large, single center, cross-sectional study. *BMC Med.* 2025 Jul 9;23(1):414. doi:10.1186/s12916-025-04193-w. PMID: 40629381
Corresponding Author Email: dongww@sj-hospital.org
Blog Categories: Epidemiology, COVID-19, Public Health Tags: COVID-19 lockdown, cardio-cerebrovascular risk, systemic inflammation, diabetes mellitus, insulin resistance, cross-sectional study, neurosurgery relevance, public health impact