The symptoms of long COVID are well‐documented. However, the long‐term effects beyond 2 years remain poorly understood due to a lack of data. This systematic review and meta‐analysis examined the prevalence of persistent symptoms in COVID‐19 survivors 3 years following initial SARS‐CoV‐2 infection. PubMed, MEDLINE (Ovid), CENTRAL, Web of Science, Scopus, and Embase were searched from inception of the databases up to July 20, 2024, by two independent researchers for articles reporting on the prevalence of persistent symptoms 3 years' post‐infection of people who survived COVID‐19 infection. We employed a random‐effect model for the pooled analysis, and the meta‐analytical effect size was prevalence for the applicable end‐points, I² statistics, and quality assessment of included studies using the Newcastle‐Ottawa Scale. Eleven articles were included after the literature search yielded 223 potentially relevant articles. We found that among patients with long COVID, fatigue, sleep disturbances, and dyspnea were the most common symptoms. Pooled analysis showed that the proportion of individuals experiencing at least one persistent symptom 3 years post‐COVID‐19 is 20% (95% confidence interval [CI]: 8–43). The prevalence of persistent symptoms was dyspnea (12%; 95% CI: 10–15), fatigue (11%; 95% CI: 6–20), insomnia (11%; 95% CI: 2–37), loss of smell (7%; 95% CI: 5–8), loss of taste (7%; 95% CI: 3–16), and anxiety (6%; 95% CI: 1–32). Prevalence of other findings include impaired diffusion capacity (42%; 95% CI: 34–50) and impaired forced expiratory volume in 1 s (10%; 95% CI: 8–12). Our findings confirm the persistence of unresolved symptoms 3 years post‐COVID‐19 infection, with implications for future research, healthcare policy, and patient care.

COVID-19 has been shown to present with varied clinical course, necessitating a need for more specific diagnostic tools that could identify severe cases and predict outcomes during COVID-19 infection. Recent evidence has shown an expanded potential role for calprotectin, both as a diagnostic tool and also as a tool in stratifying COVID-19 patients in terms of severity. Therefore, this systematic review and meta-analysis aims to evaluate the levels of calprotectin in severe and non-severe COVID-19 and also identify the implication of raised calprotectin levels. MEDLINE, EMBASE, The Cochrane Library, Web of science and MedRxiv were searched. Meta-analysis was done to compare the serum/fecal levels of calprotectin between severe and non-severe COVID-19 infections. A total of ten studies included in the review (eight had quantitative data while two were qualitative). A pooled analysis of the eight studies from 613 patients who were RT-PCR positive for COVID-19 (average age = 55 years; 52% males) showed an overall estimate as 1.34 (95%CI: 0.77, 1.91). In conclusion, calprotectin levels have been demonstrated to be significantly elevated in COVID-19 patients who develop the severe form of the disease, and it also has prognostic importance.

Vision impairment (VI) and eye diseases such as age-related macular degeneration (AMD), diabetic retinopathy (DR), glaucoma and cataract have been reported to be associated with cognitive impairment and dementia, however, to date, very little attempt has been made to collate and synthesizes such literature. Therefore, the aim of this umbrella review is to systematically assesses the credibility and certainty of evidence of associations between vision impairment (VI) and eye diseases with cognitive impairment, dementia and dementia subtypes. We conducted an umbrella review of meta-analyses by screening articles in any language in PubMed, MEDLINE (Ovid), EMBASE, Web of Science, Cochrane CENTRAL and CDSR published from database inception up to May 30, 2024. Quality appraisal of each included original meta-analysis was assessed using A Measurement Tool for Assessing Systematic Reviews 2 (AMSTAR2). The certainty of the evidence was based on statistical significance, study size, heterogeneity, small study effects, prediction intervals (PI), and bias. We followed an a-priori protocol registered with PROSPERO (CRD42024564249). We identified 13 meta-analyses (AMSTAR 2; high accuracy of the findings 1, moderate 10, and low 2) that included 232 original articles based on 99,337,354 participants. Overall, no evidence was highly suggestive or convincing. Suggestive evidence was found for associations between cataract and dementia (equivalent odds ratio [eOR] 1.20, 95 %CI, 1.16-1.25), cataract and Alzheimer's disease (eOR 1.21, 95 %CI, 1.15-1.28), and AMD and Alzheimer's disease (eOR 1.27, 95 %CI, 1.27-1.27). Weak evidence was found for associations between VI and dementia (eOR 1.50, 95 %CI, 1.23-1.84), DR and dementia (eOR 1.33, 95 %CI, 1.17-1.50), cataract and vascular dementia (eOR 1.26, 95 %CI, 1.09-1.45), VI identified by cross-sectional studies and cognitive impairment (eOR 2.37, 95 %CI, 2.31-2.44), and VI identified by objective measures and cognitive impairment (eOR 1.56, 95 %CI, 1.12-2.18). The observed suggestive level of evidence for the relationship between eye disease and dementia (as well as dementia subtypes) suggests that policy and interventions to aid in the prevention and management of eye disease may also aid in the prevention of dementia syndrome. Where the level of evidence is weak, further studies are needed with stronger methodological approaches.

There's critical need for risk predictors in long COVID. This meta‐analysis evaluates the evidence for an association between plasma lactate dehydrogenase (LDH) and long COVID and explores the contribution of LDH to symptoms persistent across the distinct post‐acute sequelae of COVID‐19 (PASC) domains. PubMed, EMBASE, Web of Science, and Google Scholar were searched for articles published up to 20 March 2023 for studies that reported data on LDH levels in COVID‐19 survivors with and without PASC. Random‐effect meta‐analysis was employed to estimate the standardized mean difference (SMD) with corresponding 95% confidence interval of each outcome. There were a total of 8289 study participants (3338 PASC vs. 4951 controls) from 46 studies. Our meta‐analysis compared to the controls showed a significant association between LDH elevation and Resp‐PASC [SMD = 1.07, 95%CI = 0.72, 1.41, p = 0.01] but not Cardio‐PASC [SMD = 1.79, 95%CI = −0.02, 3.61, p = 0.05], Neuro‐PASC [SMD = 0.19, 95%CI = −0.24, 0.61, p = 0.40], and Gastrointestinal‐PASC [SMD = 0.45, 95%CI = −1.08, 1.98, p = 0.56]. This meta‐analysis suggests elevated LDH can be used for predicting Resp‐PASC, but not Cardio‐PASC, Neuro‐PASC or gastrointestinal‐PASC. Thus, elevated plasma LDH following COVID infection may be considered as a disease biomarker.