Antibody responses to SARS-CoV-2 spike protein in a cohort of renal transplant recipients following two-dose primary immunization - A Caribbean country's perspective.

This study compares the humoral immune response of a cohort of renal transplant recipients (RTRs), in Trinidad & Tobago following two-dose primary immunization with non-mRNA vaccines amidst the COVID-19 pandemic. RTRs along with healthy, age-and gender-matched controls received either the adenoviral vector vaccine, AstraZeneca-Vaxzevria (AZ) or the inactivated vaccine, Beijing CNBG-BBIBP- CorV/Sinopharm (SP). Samples were taken after completion of a two-dose primary immunization during the period November 2021 to December 2021, at a mean interval of 138 days following immunization. 38/72 RTRs (53 %) failed to generate any protective antibody responses, compared with 7/73 participants, approximately 10 % in the healthy, age and gender-matched control group. In the RTRs, there was no significant correlation of their antibody concentration with either the timing of sample collection or the interval since transplantation. The study provides necessary information about the humoral response after two- doses of non-mRNA vaccines in a group of transplant recipients.

SARS-CoV-2 Breakthrough Infections after Third Doses Boost IgG Specific Salivary and Blood Antibodies.

SARS-CoV-2 breakthrough infections, associated with waning immunity, increase systemic antibody levels. In this study, we analyzed the impact of the infection timing on the magnitude of the systemic humoral response and whether breakthrough infections also boost antibody levels in the salivary compartment. We observed that the combination of infection plus vaccination, regardless of infection timing, produced a sharp increase in systemic antibodies, which were higher in subjects infected after third doses. Moreover, despite high systemic antibody levels, breakthrough infections after dose three occurred and boosted antibody levels in the salivary compartment. These results suggest that current vaccination strategies against COVID-19 should be improved. Results also showed that determination of salivary antibodies against SARS-CoV-2 could be a valuable tool in disease prevalence studies, for the follow-up of vaccinated individuals, and to assist vaccination strategies against COVID-19, especially in settings where blood sampling cannot be fulfilled.

Humoral response and neutralising capacity at 6 months post-vaccination against COVID-19 among institutionalised older adults in Argentina.

The COVID-19 pandemic has particularly affected older adults residing in nursing homes, resulting in high rates of hospitalisation and death. Here, we evaluated the longitudinal humoral response and neutralising capacity in plasma samples of volunteers vaccinated with different platforms (Sputnik V, BBIBP-CorV, and AZD1222). A cohort of 851 participants, mean age 83 (60-103 years), from the province of Buenos Aires, Argentina were included. Sequential plasma samples were taken at different time points after vaccination. After completing the vaccination schedule, infection-naïve volunteers who received either Sputnik V or AZD1222 exhibited significantly higher specific anti-Spike IgG titers than those who received BBIBP-CorV. Strong correlation between anti-Spike IgG titers and neutralising activity levels was evidenced at all times studied (rho=0.7 a 0.9). Previous exposure to SARS-CoV-2 and age <80 years were both associated with higher specific antibody levels. No differences in neutralising capacity were observed for the infection-naïve participants in either gender or age group. Similar to anti-Spike IgG titers, neutralising capacity decreased 3 to 9-fold at 6 months after initial vaccination for all platforms. Neutralising capacity against Omicron was between 10-58 fold lower compared to ancestral B.1 for all vaccine platforms at 21 days post dose 2 and 180 days post dose 1. This work provides evidence about the humoral response and neutralising capacity elicited by vaccination of a vulnerable elderly population. This data could be useful for pandemic management in defining public health policies, highlighting the need to apply reinforcements after a complete vaccination schedule.

Biologics in COVID-19 So Far: Systematic Review.

This systematic review aimed to reevaluate the available evidence of the use of biologics as treatment candidates for the treatment of severe and advanced COVID-19 disease; what are the rationale for their use, which are the most studied, and what kind of efficacy measures are described? A search through Cochrane, Embase, Pubmed, Medline, medrxiv.org, and Google scholar was performed on the use of biologic interventions in COVID-19/SARS-CoV-2 infection, viral pneumonia, and sepsis, until 11 January 2022. Throughout the research, we identified 4821 records, of which 90 were selected for qualitative analysis. Amongst the results, we identified five popular targets of use: IL6 and IL1 inhibitors, interferons, mesenchymal stem cells treatment, and anti-spike antibodies. None of them offered conclusive evidence of their efficacy with consistency and statistical significance except for some studies with anti-spike antibodies; however, Il6 and IL1 inhibitors as well as interferons show encouraging data in terms of increased survival and favorable clinical course that require further studies with better methodology standardization.