Similar immune response after same, different COVID-19 vaccine boosterAmong 457 adult participants in an ongoing phase 1/2 clinical trial who completed primary COVID-19 vaccination with the Moderna, Johnson & Johnson (J&J), or Pfizer/BioNTech vaccines, a booster dose with either the same (homologous) or a different brand (heterologous) induced an immune response and was safe.Baylor College of Medicine researchers led the open-label trial, published yesterday in the New England Journal of Medicine (NEJM).Adults who had completed a COVID-19 vaccine regimen of two Moderna or Pfizer doses or one J&J dose at least 12 weeks earlier received a booster dose with one of the three vaccines at 10 US sites from May 29 to Aug 13, 2021.Among the 457 participants, 154 received a booster dose with Moderna, 150 received J&J, and 153 were given Pfizer.
Participants were followed for 29 days after receipt of the booster. The researchers said they plan to monitor vaccinees for 1 year to assess long-term immune response.Regardless of whether participants received a homologous or heterologous ("mix and match") booster, neutralizing antibody concentrations against a SARS-CoV-2 pseudovirus rose fourfold, to 73, and binding levels increased fivefold, to 55.Homologous boosters increased neutralizing antibody levels fourfold, to 20, and heterologous boosters increased levels sixfold, to 73.
Spike protein-specific T-cell responses rose in all participants except for those given a homologous J&J booster.Concentrations of CD8+ T cells were most durable in those who received the J&J vaccine as their primary dose, and a heterologous J&J booster substantially increased spike-specific CD8+ T cells in those who completed primary vaccination with Moderna