Background Maintaining durable immunity following vaccination represents a major challenge, but whether mRNA booster vaccination improves durability is unknown.Methods We measured antibody responses in 55 healthy adults, who received a booster dose of the Pfizer-BioNTech or Moderna vaccine against SARS-CoV-2 and calculated the half-life of the antibody titers. We also measured memory B and T cell responses in a subset of 28 participants. In 13 volunteers who received a second booster vaccine, we measured serum antibody titers and memory B and T cell responses.Results The booster (third immunization) dose at 6 to 10 months increased the half-life of the serum–neutralizing antibody (nAb) titers to 76 days from 56 to 66 days after the primary 2-dose vaccination. A second booster dose (fourth immunization) a year after the primary vaccination further increased the half-life to 88 days. However, despite this modestly improved durability in nAb responses against the ancestral (WA.1) strain, there was a loss of neutralization capacity against the Omicron subvariants BA.2.75.2, BQ.1.1, and XBB.1.5 (48-, 71-, and 66-fold drop in titers, respectively, relative to the WA.1 strain). Although only 45% to 65% of participants demonstrated a detectable nAb titer against the newer variants after the booster (third dose), the response declined to below the detection limit in almost all individuals by 6 months. In contrast, booster vaccination induced antigen-specific memory B and T cells that persisted for at least 6 months.Conclusion The durability of serum antibody responses improves only marginally following booster immunizations with the Pfizer-BioNTech or Moderna mRNA vaccines.
Prabhu S. Arunachalam, Lilin Lai, Hady Samaha, Yupeng Feng, Mengyun Hu, Harold Sai-yin Hui, Bushra Wali, Madison Ellis, Meredith E. Davis-Gardner, Christopher Huerta, Kareem Bechnak, Sarah Bechnak, Matthew Lee, Matthew B. Litvack, Cecilia Losada, Alba Grifoni, Alessandro Sette, Veronika I. Zarnitsyna, Nadine Rouphael, Mehul S. Suthar, Bali Pulendran
Serum antibody responses following mRNA booster vaccinations.