Single-cell transcriptomics reveals pediatric immune responses to COVID-19 vaccination

Area of Science:

• Immunology
• Vaccinology
• Pediatric Infectious Diseases

Background:

• Inactivated vaccines are crucial for COVID-19 control.
• Understanding pediatric immune responses to these vaccines is essential.

Purpose of the Study:

• To characterize the cellular and molecular immune mechanisms in children following inactivated COVID-19 vaccination.
• To delineate the dynamic immune landscape after primary and booster doses of CoronaVac.

Main Methods:

• Single-cell transcriptomics was employed to analyze peripheral blood mononuclear cells (PBMCs).
• Analysis focused on B cells, CD8+ T cells, monocytes, myeloid-derived suppressor cells, and regulatory T cells.

Main Results:

• The primary vaccine dose induced memory B cells and CD8+ T cell adaptation.
• The booster dose elicited plasma cell differentiation, class-switching, and type I interferon responses in B cells.
• Vaccination promoted pro-inflammatory monocytes and expanded regulatory cells (MDSCs, Tregs) that balance immune activation.
• PGE2 signaling was identified as a key regulator in restraining cytotoxicity and orchestrating T cell responses.

Conclusions:

• Pediatric immunity to inactivated COVID-19 vaccines is a tightly regulated, two-phase process.
• The immune response balances potent antiviral programs with crucial regulatory mechanisms for safety and efficacy.