Humoral responses to SARS-CoV-2 mRNA vaccines: Role of past infection

• Published in: PloS one Vol. 16; no. 11; p. e0259703
• Main Authors: Gray, Ashley N, Martin-Blais, Rachel, Tobin, Nicole H, Wang, Yan, Brooker, Sarah L, Li, Fan, Gadoth, Adva, Elliott, Julie, Faure-Kumar, Emmanuelle, Halbrook, Megan, Hofmann, Christian, Kashani, Saman, Kazan, Clayton, Yang, Otto O, Fulcher, Jennifer A, Grovit-Ferbas, Kathie, Rimoin, Anne W, Aldrovandi, Grace M
• Format: Journal Article
• Language: English
• Published: San Francisco Public Library of Science 08.11.2021; Public Library of Science (PLoS)
• Subjects: Analysis; Antibodies; Authorship; Biology and Life Sciences; Chemiluminescence; Control; Coronaviruses; COVID-19; Decay; Decay rate; Disease transmission; Dosage; Drug dosages; Emergency response; Emergency services; Epidemics; Fire departments; Fires; Geffen, David; Health aspects; Health risks; Immune response; Immunization; Immunoassay; Infections; Infectious diseases; Medical personnel; Medicine; Medicine and Health Sciences; Microparticles; mRNA; mRNA vaccines; Pandemics; Pediatrics; Proteins; Public health; Respiratory diseases; Severe acute respiratory syndrome; Severe acute respiratory syndrome coronavirus 2; United States; Vaccines; Viral diseases; United States; Los Angeles County California; Los Angeles California; California; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0259703

Two mRNA vaccines (BNT162b2 and mRNA-1273) against severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) are globally authorized as a two-dose regimen. Understanding the magnitude and duration of protective immune responses is vital to curbing the pandemic. We enrolled 461 high-risk health services workers at the University of California, Los Angeles (UCLA) and first responders in the Los Angeles County Fire Department (LACoFD) to assess the humoral responses in previously infected (PI) and infection naïve (NPI) individuals to mRNA-based vaccines (BNT162b2/Pfizer- BioNTech or mRNA-1273/Moderna). A chemiluminescent microparticle immunoassay was used to detect antibodies against SARS-CoV-2 Spike in vaccinees prior to (n = 21) and following each vaccine dose (n = 246 following dose 1 and n = 315 following dose 2), and at days 31–60 (n = 110) and 61–90 (n = 190) following completion of the 2-dose series. Both vaccines induced robust antibody responses in all immunocompetent individuals. Previously infected individuals achieved higher median peak titers (p = 0.002) and had a slower rate of decay (p = 0.047) than infection-naïve individuals. mRNA-1273 vaccinated infection-naïve individuals demonstrated modestly higher titers following each dose (p = 0.005 and p = 0.029, respectively) and slower rates of antibody decay (p = 0.003) than those who received BNT162b2. A subset of previously infected individuals (25%) required both doses in order to reach peak antibody titers. The biologic significance of the differences between previously infected individuals and between the mRNA-1273 and BNT162b2 vaccines remains uncertain, but may have important implications for booster strategies.