Immunoassay and mass cytometry revealed immunological profiles induced by inactivated BBIBP COVID-19 vaccine

Dynamic immunogenicity after primary and booster inactivated SARS-CoV-2 vaccination in people living with HIV: A longitudinal observational study

People living with HIV (PLWH) have poor outcomes from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); vaccination reduces the associated mortality. The humoral immune response dynamics after booster inactivated vaccinations in PLWH remain unclear. In this longitudinal observational study, 100 PLWH after primary inactivated SARS-CoV-2 vaccination were consecutively recruited and followed up. After booster vaccination (BV), neutralizing antibodies (NAbs) were detected at 1 month from all the PLWH, and the titer increased sixfold compared to that associated with the primary vaccination (PV), similar to that in healthy controls after BV. The NAbs titer declined over time after BV, but remained higher at 6 months than after PV. The NAbs response was elevated after BV with CD4 count <200 cells/μL, it was the poorest among the different CD4 cell count subgroups. Similar results were observed for anti-RBD-IgG responses. Moreover, RBD-specific MBCs were significantly elevated after BV in PLWH. No serious AEs were observed after BV in PLWH. In conclusion, booster inactivated SARS-CoV-2 vaccination is well tolerated and can elicit robust and durable humoral responses in PLWH. PLWH may benefit from a third dose of the inactivated vaccine.

Post-vaccination SARS-CoV-2 seroprevalence in children aged 3-11 years and the positivity in unvaccinated children: A retrospective, single-center study

OBJECTIVE

To analyze the positivity and levels of SARS-CoV-2 antibodies in vaccinated children to evaluate the humoral immune response of vaccination on pediatric population. Analysis on the causes of antibody positivity in unvaccinated children.

METHODS

A retrospective study was conducted on children who were admitted to the Children's Hospital Affiliated to Capital Institute of Pediatrics. The clinical data of serological testing of SARS-CoV-2 immunoglobulin M (IgM) and IgG antibodies were collected from SARS-CoV-2 vaccinated or unvaccinated children with no evidence of prior novel coronavirus infection. Chemiluminescence immunoassay was utilized for the in vitro determination of SARS-CoV-2 antibodies.

RESULTS

A total of 3,321 healthy children aged 6-11 years received two doses of inactivated SARS-CoV-2 vaccine. At 1 month after the second dose, the positive rate (96.5%) and levels [8.039 (interquartile range (IQR), 6.067-9.098)] of SARS-CoV-2 IgG antibodies reached the peak and remained at a high level for 2-3 months, after which the positive rate and level of vaccine-induced IgG antibody gradually decreased. Compared with 1 month after the second dose of vaccine, the positive rate of IgG antibody decreased to 70.4% at 7 months, and the antibody level decreased by 69.0%. A total of 945 children aged 3-5 years received one or two doses of inactivated vaccine. The positive rate and levels of SARS-CoV-2 IgG antibody in participants remained high for 3 months after vaccination. There was no gender-based difference in positive rate of IgG antibody in children aged 3-11 years old (P>0.05). Among the 5,309 unvaccinated children aged 0 day to 11 years, 105 (2.0%) were positive for SARS-CoV-2 IgG antibody, which was associated with passive infusion. The maternal humoral response to COVID-19 vaccination in noninfected pregnant women was transferred through the placenta to the fetus, and some children obtained SARS-CoV-2-positive antibodies through blood transfusion.

CONCLUSIONS

Inactivated SARS-CoV-2 vaccines could induce robust humoral immune response that gradually declined within several months after the second dose. Therefore, it helps to determine whether children receive a booster dose and elicit a long-term memory immune response. Positive SARS-CoV-2 antibodies in unvaccinated children were associated with passive IgG antibody infusion.

Immunoassay and mass cytometry revealed immunological profiles induced by inactivated BBIBP COVID-19 vaccine

With the global prevalence of COVID-19 and the constant emergence of viral variants, boosters for COVID-19 vaccines to enhance antibody titers in human bodies will become an inevitable trend. However, there is a lack of data on antibody levels and the protective effects of booster injections. This study monitored and analyzed the antibody potency and the antibody responses induced by the booster injection in the subjects who received three vaccine doses. The study was conducted in a multicenter collaboration and recruited 360 healthy adults aged 20-74. Participants received the first, second, and booster doses of inactivated Sinopharm/BBIBP COVID-19 vaccine at 0, 1, and 7 months. Vaccine-induced virus-specific antibody levels (SARS-COV-2-IgA/IgM/IgG) were monitored at multiple time points, surrogate virus neutralization test (sVNT), and the spatial distribution and proportion of immune cells and markers were analyzed using the CyTOF method before vaccination and a month after the second dose. The titers of SARS-CoV-2-IgA/IgM/IgG and neutralizing antibodies increased to a high level in the first month after receiving the second dose of vaccine and declined slowly after that. The antibody levels of SARS-CoV-2-IgG and sVNT were significantly increased at 0.5 months after the induction of the booster (p < 0.05). Despite a downward trend, the antibody levels were still high in the following 6 months. The B cell concentration (in humoral sample) a month after the second injection was significantly reduced compared to that before the vaccine injection (p < 0.05). The proportion of the C01 cell cluster was significantly decreased compared with that before vaccine injection (p < 0.05). Individual cell surface markers showed distinctions in spatial distribution but were not significantly different. This study has shown that serum antibody titer levels will decrease with time by monitoring and analyzing the antibody efficacy and the antibody reaction caused by the booster injection of healthy people who received the whole vaccination (completed three injections). Still, the significant peak of the antibody titer levels after booster highlights the recall immune response. It can maintain a high concentration of antibody levels for a long time, which signifies that the protection ability has been enhanced following the injection of booster immunization. Additionally, CyTOF data shows the active production of antibodies and the change in the immunity environment.