Role of previous infection with SARS-CoV-2 in protecting against omicron reinfections and severe complications of COVID-19 compared to pre-omicron variants: a systematic review

BACKGROUND

The SARS-CoV-2 virus elicited a major public concern worldwide since December 2019 due to the high number of infections and deaths caused by COVID-19. The Omicron variant was detected in October 2021 which evolved from the wild-type SARS-CoV-2 and was found to possess many mutations. Omicron exhibited high transmissibility and immune evasion as well as reduced severity when compared to the earlier variants. Although vaccinated individuals were largely protected against infections in previous waves, the high prevalence of both reinfections and breakthrough infections with Omicron was observed. The aim of this review is to understand the effectiveness of previous infection on subsequent reinfection, given its significance in driving public health policy, including vaccination prioritization and lockdown requirements.

METHODS

A comprehensive literature search was conducted using several databases to target studies reporting data related to the effectiveness of the previous infection with SARS-CoV-2 in protecting against the Omicron variant. Screening of the studies, quality assessment and data extraction were conducted by two reviewers for each study.

RESULTS

Only 27 studies met our inclusion criteria. It was observed that previous infection was less effective in preventing reinfections with the Omicron variant compared to the Delta variant irrespective of vaccination status. Furthermore, being fully vaccinated with a booster dose provided additional protection from the Omicron variant. Additionally, most infections caused by Omicron were asymptomatic or mild and rarely resulted in hospitalizations or death in comparison to the Delta wave.

CONCLUSION

A majority of the studies reached a consensus that although previous infection provides some degree of immunity against Omicron reinfection, it is much lower in comparison to Delta. Full vaccination with two doses was more protective against Delta than Omicron. Receiving a booster dose provided additional protection against Omicron. It is therefore clear that neither vaccination nor previous infection alone provide optimal protection; hybrid immunity has shown the best results in terms of protecting against either Omicron or Delta variants. However, additional research is needed to quantify how long immunity from vaccination versus previous infection lasts and whether individuals will benefit from variant-specific vaccinations to enhance protection from infection.

Severity of the Omicron SARS-CoV-2 variant compared with the previous lineages: A systematic review

The Omicron variant was first detected in October 2021, which evolved from the original SARS-CoV-2 strain and was found to possess many mutations. Immune evasion was one of the notable consequences of these mutations. Despite Omicron exhibiting increased transmissibility, the rates of hospitalizations and deaths among patients infected with this variant were substantially lower when compared to other strains. However, concluding that the Omicron variant is less severe than other variants of SARS-CoV-2 requires consideration of multiple factors, including the vaccination status of infected patients as well as any previous infections with other variants. This review compiled data about any reported indicators of severity in Omicron-infected patients, including studies comparing Omicron with other variants while adjusting for confounders. A comprehensive search was conducted using different databases to target any studies about Omicron. In total, 62 studies met our inclusion criteria and were included in this study. Many studies reported a significantly reduced risk of hospitalization, ICU admission, need for oxygenation/ventilation, and death in Omicron-infected patients compared to patients infected with other variants, such as Delta. Some studies, however, reported comparable severity in Omicron infected patients as to other variants emphasizing a substantial risk for severe illness. Furthermore, the COVID-19 vaccines were less effective against Omicron relative to previous lineages, except after receiving the booster dose. One study recommended vaccination during pregnancy, which may help prevent future cases of severe SARS-CoV-2 pneumonia in neonates and young infants due to the transfer of humoral response from the mother.

Can probiotic, prebiotic, and synbiotic supplementation modulate the gut-liver axis in type 2 diabetes? A narrative and systematic review of clinical trials

Background

Type 2 diabetes, one of the most common noncommunicable diseases, is a metabolic disorder that results in failed homeostatic control in several body systems, including hepatic function. Due to the gut microbiome’s potential role in diabetes’ pathogenesis, prebiotics, probiotics, and synbiotics have been proposed as complimentary therapeutic approaches aimed at microbiota readjustment.

Methods

A systematic review was conducted on PubMed, Scopus, Web of Science, Embase, and the Cochrane Library examining the effect of probiotics, prebiotics, and synbiotics on hepatic biomarkers in patients with diabetes.

Results

From 9,502 search hits, 10 studies met the inclusion criteria and were included in this review. A total of 816 participants (460 intervention and 356 control) were investigated for the effects of nine different hepatic biomarker measurements including aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, total protein, bilirubin, liver steatosis, liver stiffness, fatty liver index, and gamma-glutamyl transferase levels. Of the 13 intervention groups analyzed from the 10 studies, 3 were prebiotic interventions, 3 were single species probiotic interventions, 3 were multi-species probiotic interventions, and 4 were synbiotic interventions. Nutraceuticals used in these trials included six genera of bacteria (Lactobacillus, Bifidobacterium, Streptococcus, Acetobacter, Lactococcus, and Propionibacterium), five different prebiotic formulations (inulin, inulin and beta carotene, chicory inulin enriched with oligofructose, galacto-oligosaccharides syrup, and powdered cinnamon), or a combination of these to form multi-species probiotics or synbiotics.

Conclusion

Although some studies showed insignificant changes in hepatic biomarkers, generally the results yielded a decrease in liver damage due to reduced oxidative stress, pro-inflammatory cytokines, gut dysbiosis, and insulin resistance which led to improvements in hepatic biomarker levels.

Development and characterization of microsatellite primers for Triops granarius (Branchiopoda: Notostraca) using MiSeq technology

Background

Next-generation sequencing technology has allowed for the rapid development of microsatellites, neutral polymorphic markers that can be used for the analysis of population structure.

Methods and Results

In this study, we performed whole-genome sequencing using the Illumina MiSeq system and de novo assembly to design microsatellite primers for Triops granarius populations in Qatar. The developed microsatellites are suitable for future studies of genetic structuring among geographically isolated freshwater pools. A total of 23 different primer pairs produced typical microsatellite results, with each pair successfully amplified in up to 40 individuals. Only five of the loci produced a significant departure from Hardy-Weinberg equilibrium.

Conclusions

Some of the underlying mechanisms regarding the few loci that deviated from HWE may be further investigated to determine the source of deviation. As T. granarius is the most widely distributed species of the family, the development of these molecular markers would be useful for conducting population genetics and biogeographical studies broadly.

213 A Novel, Cost-Effective and Convenient Model for Simulating Facial Wound Repair

Introduction

We describe the use of a novel synthetic simulation pad for learning complex facial wound management including local flaps. The simulation pad is a cost effective and convenient model of facial wounds. We have compared the use of animal tissue to the simulation pad in the context of a workshop for surgical trainees and collected feedback from delegates.

Methods

Feedback was collected from 14 of 16 attending delegates.

Results

It was clear from feedback that animal tissue is not an ideal model of facial wounds with 71% of delegates stating that they did not consider it to be high-fidelity. The synthetic pad was rated more favourably with 100% of delegates reporting that it was a valuable exercise and well designed for local flaps.

Conclusions

It is imperative that training opportunities are high quality and useful to clinical practice. Techniques learnt in the context of a course or workshop are more valuable where targeted practice may occur following learning. The use of a synthetic pad is more amenable to continued practice where it may be taken home following a workshop. Feedback from this event suggests a well-designed synthetic pad is more useful than animal tissue in learning local flaps.

Three changes to reduce the loss of dual degree trainees from OMFS national specialty selection in the UK: evidence based proposals

The training pathway for oral and maxillofacial surgery (OMFS) has remained relatively stable for around 30 years. Circumstances surrounding the training pathway have changed including the priorities of individuals considering entering OMFS training. Run-through Specialty Training (ST1) OMFS posts (which include core surgical training) are oversubscribed while direct entry to Specialty Training (ST3) OMFS specialty recruitment rounds have unfilled posts, including places declined by appointable candidates. As part of a project to refine and improve OMFS recruitment and retention, data drawn from the British Association of Oral and Maxillofacial Surgeons (BAOMS) and the OMFS National Selection administering Deanery, Health Education England South West were scrutinised. Numbers of students starting second undergraduate degrees (medicine or dentistry) to pursue an OMFS career are increasing. Of a total of 43 candidates deemed appointable at OMFS ST1 selection but not offered an available post, 16 did not subsequently apply for ST3 selection. In the period studied (2015-20), of a total of 116 unfilled ST3 posts, 39 remained vacant because appointable candidates declined the available posts (33%). Appropriate changes to the current national selection processes could help address the perceived OMFS ST recruitment problems. By increasing the number of available ST1 posts, widening the window during which appointable candidates can continue into training and increasing prior experience recognition (including creating benchmarking processes prior to ST). These 3 clear, fair and transparent changes could reduce the current levels of attrition.

A rare case of multiple right heart myxomas

Primary tumours of the heart are rare. Myxomas are the most common primary cardiac tumours with an estimated incidence of 0.5 per million population per year. Myxomas are most commonly found in left atrium and are solitary in more than 90% cases. Familial myxomas are rarer and tend to be multiple. We report a rare case of multiple myxomas in the right heart which occurred sporadically, presenting with an episode of pre-syncope.