biostudies-literatureShah MMNCATS NIH HHSNIAID NIH HHSNCI NIH HHSNIAMS NIH HHS2502-2523https://www.ebi.ac.uk/biostudies/studies/S-EPMC11368657biostudies-literatureUnknown79(9)<h4>Background</h4>During the COVID-19 pandemic, novel nanoparticle-based mRNA vaccines were developed. A small number of individuals developed allergic reactions to these vaccines although the mechanisms remain undefined.<h4>Methods</h4>To understand COVID-19 vaccine-mediated allergic reactions, we enrolled 19 participants who developed allergic events within 2 h of vaccination and 13 controls, nonreactors. Using standard hemolysis assays, we demonstrated that sera from allergic participants induced stronger complement activation compared to nonallergic subjects following ex vivo vaccine exposure.<h4>Results</h4>Vaccine-mediated complement activation correlated with anti-polyethelyne glycol (PEG) IgG (but not IgM) levels while anti-PEG IgE was undetectable in all subjects. Depletion of toAllergyElucidating allergic reaction mechanisms in response to SARS-CoV-2 mRNA vaccination in adults.PMC11368657UL1 TR002345P30 AR073752U19 AI167903U19 AI057229U54 CA260517Heider ALiu JAkk ARen ZShah MMPatterson AChinthrajah SO'Hara RLee ASDurham SRTan TJKendall PLDavis MMPham CTNChang IDunham DPark HArunachalam PSBoyd SDGibbs BFFulton WTVel MSPulendran BHourcade DESindher SBNadeau KCMonroy JMAkdis CAFernandes AGalli SJAgache IShamji MHJerath MRLayhadi JAMitchell LMFedina AfalseElucidating allergic reaction mechanisms in response to SARS-CoV-2 mRNA vaccination in adults.<h4>Background</h4>During the COVID-19 pandemic, novel nanoparticle-based mRNA vaccines were developed. A small number of individuals developed allergic reactions to these vaccines although the mechanisms remain undefined.<h4>Methods</h4>To understand COVID-19 vaccine-mediated allergic reactions, we enrolled 19 participants who developed allergic events within 2 h of vaccination and 13 controls, nonreactors. Using standard hemolysis assays, we demonstrated that sera from allergic participants induced stronger complement activation compared to nonallergic subjects following ex vivo vaccine exposure.<h4>Results</h4>Vaccine-mediated complement activation correlated with anti-polyethelyne glycol (PEG) IgG (but not IgM) levels while anti-PEG IgE was undetectable in all subjects. Depletion of to2024-01-01T00:00:00Z2024 Sep2026-05-29T07:02:43.689Z2026-04-08T03:52:37.019ZS-EPMC113686573903331210.1111/all.16231