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Vaccines (Basel) ; 10(7)2022 Jun 30.
Article in English | MEDLINE | ID: covidwho-1917867


The advent of the Omicron variant globally has hastened the requirement for a booster vaccination dose to confer continuous protection against symptomatic SARS-CoV2 infection. However, different vaccines are available in different countries, and individuals who had adverse reactions to certain vaccine types require heterologous vaccine boosters. To understand the efficacy of different vaccination regimens in inducing humoral responses to SARS-CoV2, we examined plasma antibodies and frequencies of Omicron RBD-specific B cells in individuals who had different priming-booster vaccination regimens. We found that individuals with three homologous doses of mRNA vaccines had higher levels of IgG of all subclasses against RBD of Omicron than individuals with three homologous doses of inactivated virus vaccine. A booster with mRNA vaccine resulted in significant increases in median levels of RBD-reactive IgG1 (17-19 fold) and IgG3 (2.3-3.3 fold) as compared to individuals receiving inactivated virus booster shots regardless of priming vaccine types. More importantly, individuals who received a booster dose of mRNA vaccine, irrespective of the priming vaccine, had antibodies with higher neutralizing capability against the Omicron variant than those who received a booster dose of inactivated virus vaccine. Corroborating the antibody results, boosting with the mRNA vaccine increased the frequencies of Omicron RBD-binding B cells by (1.5-3.3 fold) regardless of priming vaccine types. Together, our data demonstrate that an mRNA vaccine (BNT162b2 or mRNA-1273) booster enhances humoral responses against the Omicron variant in individuals vaccinated with either two prior doses of mRNA or inactivated virus vaccine (CoronaVac or BBIBP-CorV), potentially providing more effective protection against SARS-CoV-2 infection, particularly by the Omicron variant.

Front Immunol ; 12: 710217, 2021.
Article in English | MEDLINE | ID: covidwho-1555700


Severe SARS-CoV-2 infection can trigger uncontrolled innate and adaptive immune responses, which are commonly associated with lymphopenia and increased neutrophil counts. However, whether the immune abnormalities observed in mild to severely infected patients persist into convalescence remains unclear. Herein, comparisons were drawn between the immune responses of COVID-19 infected and convalescent adults. Strikingly, survivors of severe COVID-19 had decreased proportions of NKT and Vδ2 T cells, and increased proportions of low-density neutrophils, IgA+/CD86+/CD123+ non-classical monocytes and hyperactivated HLADR+CD38+ CD8+ T cells, and elevated levels of pro-inflammatory cytokines such as hepatocyte growth factor and vascular endothelial growth factor A, long after virus clearance. Our study suggests potential immune correlates of "long COVID-19", and defines key cells and cytokines that delineate true and quasi-convalescent states.

COVID-19/immunology , SARS-CoV-2/immunology , Adult , Aged , COVID-19/complications , Cohort Studies , Convalescence , Female , Humans , Male , Middle Aged