Persistence of SARS-CoV-2 antibodies over 18 months following infection: UK Biobank COVID-19 Serology Study

Plasma proteomic evidence for increased β-amyloid pathology after SARS-CoV-2 infection

Previous studies have suggested that systemic viral infections may increase risks of dementia. Whether this holds true for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus infections is unknown. Determining this is important for anticipating the potential future incidence of dementia. To begin to do this, we measured plasma biomarkers linked to Alzheimer's disease pathology in the UK Biobank before and after serology-confirmed SARS-CoV-2 infections. SARS-CoV-2 infection was associated with biomarkers associated with β-amyloid pathology: reduced plasma Aβ42:Aβ40 ratio and, in more vulnerable participants, lower plasma Aβ42 and higher plasma pTau-181. The plasma biomarker changes were greater in participants who had been hospitalized with COVID-19 or had reported hypertension previously. We showed that the changes in biomarkers were linked to brain structural imaging patterns associated with Alzheimer's disease, lower cognitive test scores and poorer overall health evaluations. Our data from this post hoc case-control matched study thus provide observational biomarker evidence that SARS-CoV-2 infection can be associated with greater brain β-amyloid pathology in older adults. While these results do not establish causality, they suggest that SARS-CoV-2 (and possibly other systemic inflammatory diseases) may increase the risk of future Alzheimer's disease.

Assessment of the prevalence of respiratory pathogens and the level of immunity to respiratory viruses in soldiers and civilian military employees in Poland

BACKGROUND

This study provides a detailed analysis of respiratory tract infections (RTIs) and immunity levels against influenza and SARS-CoV-2 among soldiers and military personnel in Poland. Owing to their unique service environments, this occupational group is at high risk. During deployments, they often face adverse physical conditions, close living quarters, and exposure to both local and endemic pathogens. It particularly increases their susceptibility to RTIs, which remain a leading cause of illness worldwide.

METHODS

The study cohort included 379 participants aged between 19 and 60 years. We used polymerase chain reaction (PCR) techniques to detect 34 common respiratory pathogens and analyzed blood serum samples to assess the degree of immunity against the influenza A, B, and SARS-CoV-2 viruses. In 78.10% of the participants, at least one respiratory pathogen was detected.

RESULTS

Human rhinovirus (HRV) was the most common (8.71%), followed by SARS-CoV-2 (4.75%) and influenza A (H1N1) sw (2.90%). Staphylococcus aureus was the most prevalent bacterial pathogen (18.47%), with significant occurrences of Haemophilus influenzae (14.24%) and Klebsiella pneumoniae (9.76%). Additionally, 52.3% of those with coinfections had combinations of bacterial and viral pathogens, highlighting the complexity of diagnosing and managing these infections. We also assessed immunity levels, which focused on antibodies specific to influenza A/B and SARS-CoV-2 viruses. For all the results obtained, statistical analyses were performed. A weak positive correlation between age and levels of anti-influenza antibodies was observed, suggesting a slight increase in antibody levels with age. A total of 81.53% of the participants had received at least one dose of the SARS-CoV-2 vaccine. A significant correlation between the number of vaccine doses and higher anti-SARS-CoV-2 IgG antibodies was observed, indicating stronger immunity with more vaccinations.

CONCLUSIONS

This study underscores the importance of specialized health monitoring and preventive measures such as vaccinations to protect military personnel from RTIs and maintain their operational readiness. The detailed analysis of pathogen prevalence and immunity levels offers valuable insights into this occupational group's health risks and needs.

CLINICAL TRIAL NUMBER

Not applicable.

Post-acute sequelae of SARS-CoV-2 mimic: An important neurological condition

BACKGROUND AND OBJECTIVES

In 2024, the sequalae of the acute phase of coronavirus disease-19 (COVID-19) infection, which include neurological symptoms and are commonly referred to as long COVID or post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (PASC), continue to be a substantial health concern; however, similar symptoms are observed in individuals with no previous COVID-19 infection.

METHODS

This was a single-center, retrospective, descriptive case series study. Data were obtained from patients who visited our outpatient clinic specializing in PASC between June 1, 2021, and May 31, 2023. We compared antibody test results between patients with confirmed acute phase infection and those without. We compared differences in demographic and clinical characteristics between patients with positive results during the acute phase of COVID-19 infection and positive anti-SARS-CoV-2 antibody tests (true-PASC), and those with neither (PASC-mimic).

RESULTS

Of 437 patients diagnosed with PASC according to World Health Organization criteria, 222 underwent COVID-19 antibody tests. Of these, 193 patients (86.9%) had a history of confirmed acute phase infection, whereas 29 (13.1%) did not. Of the former, 186 patients (96.4%) were seropositive for anti-nucleotide SARS-CoV-2 antibodies (true-PASC), whereas 19 of the latter tested seronegative for anti-nucleotide SARS-CoV-2 antibodies (PASC-mimic). There were no significant differences in symptom characteristics between true-PASC and PASC-mimic participants.

CONCLUSIONS

It was difficult to identify any clinical features to aid in diagnosing PASC without confirmation of acute COVID-19 infection. The findings indicate the existence of a "PASC-mimic" condition that should be acknowledged and excluded in future PASC-related research studies.

A mathematical model for the within-host (re)infection dynamics of SARS-CoV-2

Interactions between SARS-CoV-2 and the immune system during infection are complex. However, understanding the within-host SARS-CoV-2 dynamics is of enormous importance for clinical and public health outcomes. Current mathematical models focus on describing the within-host SARS-CoV-2 dynamics during the acute infection phase. Thereby they ignore important long-term post-acute infection effects. We present a mathematical model, which not only describes the SARS-CoV-2 infection dynamics during the acute infection phase, but extends current approaches by also recapitulating clinically observed long-term post-acute infection effects, such as the recovery of the number of susceptible epithelial cells to an initial pre-infection homeostatic level, a permanent and full clearance of the infection within the individual, immune waning, and the formation of long-term immune capacity levels after infection. Finally, we used our model and its description of the long-term post-acute infection dynamics to explore reinfection scenarios differentiating between distinct variant-specific properties of the reinfecting virus. Together, the model's ability to describe not only the acute but also the long-term post-acute infection dynamics provides a more realistic description of key outcomes and allows for its application in clinical and public health scenarios.

SARS-CoV-2 Neutralizing Antibodies in Three African Countries Following Multiple Distinct Immune Challenges

BACKGROUND

The COVID-19 pandemic has affected Madagascar, Cameroon, and the Central African Republic (CAR), with each experiencing multiple waves by mid-2022. This study aimed to evaluate immunity against SARS-CoV-2 strains Wuhan (W) and BA.2 (BA.2) among healthcare workers (HCWs) in these countries, focusing on vaccination and natural infection effects.

METHODS

HCWs' serum samples were analyzed for neutralizing antibodies (nAbs) against W and BA.2 variants, with statistical analyses comparing responses between countries and vaccination statuses.

RESULTS

Madagascar showed significantly higher nAb titers against both strains compared to CAR and Cameroon. Vaccination notably increased nAb levels against W by 2.6-fold in CAR and 1.8-fold in Madagascar, and against BA.2 by 1.6-fold in Madagascar and 1.5-fold in CAR. However, in Cameroon, there was no significant difference in nAb levels between vaccinated and unvaccinated groups.

CONCLUSION

This study highlights the complex relationship between natural and vaccine-induced immunity, emphasizing the importance of assessing immunity in regions with varied epidemic experiences and low vaccination rates.