Natural infection versus hybrid (natural and vaccination) humoral immune response to SARS-CoV-2: a comparative paired analysis

A Meta-analysis of Severe Acute Respiratory Syndrome Coronavirus 2 Anti-spike Immunoglobulin G Antibody Durability up to 9 Months After Full Vaccination in Adults

This meta-analysis aims to estimate temporal decline in vaccine-induced antibodies against severe acute respiratory syndrome coronavirus 2 up to 9 months after full vaccination contributing to overall understanding of coronavirus disease 2019 infection protection. We identified 15 eligible studies and calculated standardized mean differences (SMD) between antibody concentrations at 1, 3, 6, and 9 months after full vaccination. Overall SMD between 1 month after vaccination and 3 months was -1.14 (95% CI -1.52, -0.76), at 6 months was -1.06 (95% CI -1.30, -0.81), and at 9 months, it was -0.77 (95% CI -0.94, -0.60) suggesting a moderate decline over time.

Obesity does not influence SARS-CoV-2 humoral vaccine immunogenicity

Obesity is a recognized factor influencing immune function and infectious disease outcomes. Characterization of the influence of obesity on SARS-CoV-2 humoral vaccine immunogenicity is required to properly tailor vaccine type (mRNA, viral-vector, protein subunit vaccines) and dosing schedule. Data from a prospective cohort study collected over 34 months was used to evaluate the slope of antibody production and decay and neutralizing capacity following SARS-CoV-2 vaccination in individuals with and without obesity at baseline. Most participants were female (65.4%), white (92.4%), and received mRNA vaccines. 210 were obese and 697 non-obese. Sex and infection-acquired immunity were identified as effect modifiers for the relationship between obesity and COVID-19 vaccine humoral immunogenicity. No consistent influence of obesity on peak titres, titre retention, antibody isotype (IgG, IgM, IgA), or neutralization was identified when controlling for other key variables. It may not be necessary to consider this variable when developing SARS-CoV-2 vaccine dosing strategies.

The Ambivalence of Post COVID-19 Vaccination Responses in Humans

The Coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has prompted a massive global vaccination campaign, leading to the rapid development and deployment of several vaccines. Various COVID-19 vaccines are under different phases of clinical trials and include the whole virus or its parts like DNA, mRNA, or protein subunits administered directly or through vectors. Beginning in 2020, a few mRNA (Pfizer-BioNTech BNT162b2 and Moderna mRNA-1273) and adenovirus-based (AstraZeneca ChAdOx1-S and the Janssen Ad26.COV2.S) vaccines were recommended by WHO for emergency use before the completion of the phase 3 and 4 trials. These vaccines were mostly administered in two or three doses at a defined frequency between the two doses. While these vaccines, mainly based on viral nucleic acids or protein conferred protection against the progression of SARS-CoV-2 infection into severe COVID-19, and prevented death due to the disease, their use has also been accompanied by a plethora of side effects. Common side effects include localized reactions such as pain at the injection site, as well as systemic reactions like fever, fatigue, and headache. These symptoms are generally mild to moderate and resolve within a few days. However, rare but more serious side effects have been reported, including allergic reactions such as anaphylaxis and, in some cases, myocarditis or pericarditis, particularly in younger males. Ongoing surveillance and research efforts continue to refine the understanding of these adverse effects, providing critical insights into the risk-benefit profile of COVID-19 vaccines. Nonetheless, the overall safety profile supports the continued use of these vaccines in combating the pandemic, with regulatory agencies and health organizations emphasizing the importance of vaccination in preventing COVID-19's severe outcomes. In this review, we describe different types of COVID-19 vaccines and summarize various adverse effects due to autoimmune and inflammatory response(s) manifesting predominantly as cardiac, hematological, neurological, and psychological dysfunctions. The incidence, clinical presentation, risk factors, diagnosis, and management of different adverse effects and possible mechanisms contributing to these effects are discussed. The review highlights the potential ambivalence of human response post-COVID-19 vaccination and necessitates the need to mitigate the adverse side effects.

Comparative outcomes of SARS-CoV-2 primary and reinfection in older adult patients

Background

The outcomes of older adult people acquiring SARS-CoV-2 reinfection was unclear. This study aimed to compare the outcomes of older adult patients with COVID-19 reinfection and those with primary infection.

Methods

This retrospective cohort study used electronic medical records from the TriNetX Research Network. Older adult patients (aged ≥65 years) with COVID-19 between January 1, 2022, and December 31, 2022, were included in the study. The patients were subsequently categorized into reinfection or primary infection groups, according to whether they manifested two distinct COVID-19 episodes with an intervening period of more than 90 days. Propensity score matching was performed for covariate adjustment between the reinfection and primary infection groups. The primary outcome was a composite outcome, including emergency department visits, hospitalization, intensive care unit admission, mechanical ventilation use, and mortality, following primary infection and reinfection.

Results

After matching, 31,899 patients were identified in both the reinfection and primary infection groups. The risk of primary composite outcomes was 7.15% (n = 2,281) in the reinfection group and 7.53% (n = 2,403) in the primary infection group. No significant difference in the primary outcome was observed between groups (HR, 0.96; 95% CI, 0.91 to 1.02, p = 0.17). In addition, there was no significant differences between the reinfection and primary infection groups in terms of emergency department visit (HR, 1.03; 95% CI, 0.95 to 1.11, p = 0.49), all-cause hospitalization (HR, 0.94; 95% CI, 0.86 to 1.02, p = 0.14), intensive care unit admission (HR, 0.92; 95% CI, 0.67 to 1.28, p = 0.62), mechanical ventilation use (HR,1.35 95% CI, 0.69 to 2.64 p = 0.38), and all-cause mortality (HR, 0.94; 95% CI, 0.74 to 1.20, p = 0.62).

Conclusion

There were no significant differences in clinical outcomes between older adult patients with COVID-19 reinfection and those with primary infection.