Immunogenicity of mRNA vs. BBV152 vaccine boosters against Omicron subvariants: Final results from Phase B of the PRIBIVAC study, a randomized clinical trial.

Background: BBV152 (Covaxin™) is a whole-virion inactivated SARS-CoV-2 vaccine mixed with an immune adjuvant. We aimed to compare immune responses after booster vaccination with heterologous BBV152 versus homologous mRNA vaccine.

Methods: We conducted a randomized, participant-blinded, controlled trial.

Imprinting of IgA responses in previously infected individuals receiving bivalent mRNA vaccines (WT and BA.4/BA.5 or WT and BA.1).

Objectives: The emergence of new SARS-CoV-2 variants has led to the development of Omicron-targeting bivalent mRNA vaccines. It is crucial to understand how bivalent vaccines may improve antibody responses against new variants.

Methods: A total of 107 participants, who had three COVID-19 WT mRNA vaccine doses, were recruited, and given either a monovalent (WT) or a bivalent mRNA vaccination (Pfizer/BioNTech Bivalent (WT and BA.

Higher Delta variant-specific neutralizing antibodies prevented infection in close contacts vaccinated with ancestral mRNA vaccines during the SARS-CoV-2 Delta wave.

Identification of the risk factors and the high-risk groups which are most vulnerable is critical in COVID-19 disease management at a population level. Evaluating the efficacy of vaccination against infections is necessary to determine booster vaccination strategies for better protection in high-risk groups. In this study, we recruited 158 mRNA-vaccinated individuals during the Delta wave of SARS-CoV-2 infections in Singapore and examined the antibody profiles of infected individuals.

Third dose of BNT162b2 improves immune response in liver transplant recipients to ancestral strain but not Omicron BA.1 and XBB.

Vaccine immunogenicity in transplant recipients can be impacted by the immunosuppressive (IS) regimens they receive. While BNT162b2 vaccination has been shown to induce an immune response in liver transplant recipients (LTRs), it remains unclear how different IS regimens may affect vaccine immunogenicity after a third BNT162b2 dose in LTRs, which is especially important given the emergence of the Omicron sublineages of SARS-CoV-2. A total of 95 LTRs receiving single and multiple IS regimens were recruited and offered three doses of BNT162b2 during the study period.

Conserved longitudinal alterations of anti-S-protein IgG subclasses in disease progression in initial ancestral Wuhan and vaccine breakthrough Delta infections.

Introduction: COVID-19 has a wide disease spectrum ranging from asymptomatic to severe. While humoral immune responses are critical in preventing infection, the immune mechanisms leading to severe disease, and the identification of biomarkers of disease progression and/or resolution of the infection remains to be determined.

Methods: Plasma samples were obtained from infections during the initial wave of ancestral wildtype SARS-CoV-2 and from vaccine breakthrough infections during the wave of Delta variant, up to six months post infection.

Waning of specific antibodies against Delta and Omicron variants five months after a third dose of BNT162b2 SARS-CoV-2 vaccine in elderly individuals.

The emergence of new SARS-CoV-2 variants, such as the more transmissible Delta and Omicron variants, has raised concerns on efficacy of the COVID-19 vaccines. Here, we examined the waning of antibody responses against different variants following primary and booster vaccination. We found that antibody responses against variants were low following primary vaccination.

Efficient recall of SARS-CoV-2 variant-reactive B cells and T responses in the elderly upon heterologous mRNA vaccines as boosters.

Waning antibody levels against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the emergence of variants of concern highlight the need for booster vaccinations. This is particularly important for the elderly population, who are at a higher risk of developing severe coronavirus disease 2019 (COVID-19) disease. While studies have shown increased antibody responses following booster vaccination, understanding the changes in T and B cell compartments induced by a third vaccine dose remains limited.

Heterologous booster vaccination with CoronaVac following prime vaccination with mRNA vaccine.

Objective: Despite the high vaccine efficacy of mRNA COVID-19 vaccines, there are individuals who developed excessive reactogenic and/or allergic responses after the first mRNA dose and were considered ineligible for further mRNA doses. CoronaVac, an inactivated SARS-CoV-2 vaccine, is recommended in Singapore as an alternative.

Methods: Individuals, ineligible for further mRNA vaccines (BNT162b2 or mRNA-1273) because of excessive reactive responses to prime mRNA vaccination, were recruited and offered two doses of CoronaVac as booster vaccination 38-224 days post their mRNA vaccine dose.

Decreased memory B cell frequencies in COVID-19 delta variant vaccine breakthrough infection.

The SARS-CoV-2 Delta (B.1.617.

Gut-Evolved Induces Metabolic Changes in Neutrophils.

Serial passaging of the human fungal pathogen in the gastrointestinal tract of antibiotics-treated mice selects for virulence-attenuated strains. These gut-evolved strains protect the host from infection by a wide range of pathogens trained immunity. Here, we further investigated the molecular and cellular mechanisms underlying this innate immune memory.

Resistance of SARS-CoV-2 variants to neutralization by convalescent plasma from early COVID-19 outbreak in Singapore.

The rapid spreading of SARS-CoV-2 variants B.1.1.

PET Imaging of Translocator Protein as a Marker of Malaria-Associated Lung Inflammation.

Malaria-associated acute respiratory distress syndrome (MA-ARDS) is a severe complication of malaria that occurs despite effective antimalarial treatment. Currently, noninvasive imaging procedures such as chest X-rays are used to assess edema in established MA-ARDS, but earlier detection methods are needed to reduce morbidity and mortality. The early stages of MA-ARDS are characterized by the infiltration of leukocytes, in particular monocytes/macrophages; thus, monitoring of immune infiltrates may provide a useful indicator of early pathology.

Microbial exposure during early human development primes fetal immune cells.

The human fetal immune system begins to develop early during gestation; however, factors responsible for fetal immune-priming remain elusive. We explored potential exposure to microbial agents in utero and their contribution toward activation of memory T cells in fetal tissues. We profiled microbes across fetal organs using 16S rRNA gene sequencing and detected low but consistent microbial signal in fetal gut, skin, placenta, and lungs in the 2 trimester of gestation.

Sensitive detection of total anti-Spike antibodies and isotype switching in asymptomatic and symptomatic individuals with COVID-19.

Early detection of infection is crucial to limit the spread of coronavirus disease 2019 (COVID-19). Here we develop a flow cytometry-based assay to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (S) protein antibodies in individuals with COVID-19. The assay detects specific immunoglobulin M (IgM), IgA, and IgG in individuals with COVID-19 and also acquisition of all IgG subclasses, with IgG1 being the most dominant.