Your browser doesn't support javascript.
Show: 20 | 50 | 100
Results 1 - 4 de 4
Clin Infect Dis ; 2022 Jun 20.
Article in English | MEDLINE | ID: covidwho-1901150


The emergence of SARS-CoV-2 variants raised questions regarding the durability of immune responses after homologous or heterologous booster vaccination after Ad26.COV2.S priming. We found that SARS-CoV-2-specific binding antibodies, neutralizing antibodies and T-cells are detectable 5 months after boosting, although waning of antibodies and limited cross-reactivity with Omicron BA.1 was observed.

Sci Immunol ; 7(69): eabo2202, 2022 03 25.
Article in English | MEDLINE | ID: covidwho-1673343


The severe acute respiratory distress syndrome coronavirus 2 (SARS-CoV-2) Omicron variant is spreading rapidly, even in vaccinated individuals, raising concerns about immune escape. Here, we studied neutralizing antibodies and T cell responses targeting SARS-CoV-2 D614G [wild type (WT)] and the Beta, Delta, and Omicron variants of concern in a cohort of 60 health care workers after immunization with ChAdOx-1 S, Ad26.COV2.S, mRNA-1273, or BNT162b2. High binding antibody levels against WT SARS-CoV-2 spike (S) were detected 28 days after vaccination with both mRNA vaccines (mRNA-1273 or BNT162b2), which substantially decreased after 6 months. In contrast, antibody levels were lower after Ad26.COV2.S vaccination but did not wane. Neutralization assays showed consistent cross-neutralization of the Beta and Delta variants, but neutralization of Omicron was significantly lower or absent. BNT162b2 booster vaccination after either two mRNA-1273 immunizations or Ad26.COV2 priming partially restored neutralization of the Omicron variant, but responses were still up to 17-fold decreased compared with WT. SARS-CoV-2-specific T cells were detected up to 6 months after all vaccination regimens, with more consistent detection of specific CD4+ than CD8+ T cells. No significant differences were detected between WT- and variant-specific CD4+ or CD8+ T cell responses, including Omicron, indicating minimal escape at the T cell level. This study shows that vaccinated individuals retain T cell immunity to the SARS-CoV-2 Omicron variant, potentially balancing the lack of neutralizing antibodies in preventing or limiting severe COVID-19. Booster vaccinations are needed to further restore Omicron cross-neutralization by antibodies.

COVID-19 , SARS-CoV-2 , CD8-Positive T-Lymphocytes , COVID-19/prevention & control , COVID-19 Vaccines , Humans
N Engl J Med ; 386(10): 951-963, 2022 03 10.
Article in English | MEDLINE | ID: covidwho-1642068


BACKGROUND: The Ad26.COV2.S vaccine, which was approved as a single-shot immunization regimen, has been shown to be effective against severe coronavirus disease 2019. However, this vaccine induces lower severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein (S)-specific antibody levels than those induced by messenger RNA (mRNA)-based vaccines. The immunogenicity and reactogenicity of a homologous or heterologous booster in persons who have received an Ad26.COV2.S priming dose are unclear. METHODS: In this single-blind, multicenter, randomized, controlled trial involving health care workers who had received a priming dose of Ad26.COV2.S vaccine, we assessed immunogenicity and reactogenicity 28 days after a homologous or heterologous booster vaccination. The participants were assigned to receive no booster, an Ad26.COV2.S booster, an mRNA-1273 booster, or a BNT162b2 booster. The primary end point was the level of S-specific binding antibodies, and the secondary end points were the levels of neutralizing antibodies, S-specific T-cell responses, and reactogenicity. A post hoc analysis was performed to compare mRNA-1273 boosting with BNT162b2 boosting. RESULTS: Homologous or heterologous booster vaccination resulted in higher levels of S-specific binding antibodies, neutralizing antibodies, and T-cell responses than a single Ad26.COV2.S vaccination. The increase in binding antibodies was significantly larger with heterologous regimens that included mRNA-based vaccines than with the homologous booster. The mRNA-1273 booster was most immunogenic and was associated with higher reactogenicity than the BNT162b2 and Ad26.COV2.S boosters. Local and systemic reactions were generally mild to moderate in the first 2 days after booster administration. CONCLUSIONS: The Ad26.COV2.S and mRNA boosters had an acceptable safety profile and were immunogenic in health care workers who had received a priming dose of Ad26.COV2.S vaccine. The strongest responses occurred after boosting with mRNA-based vaccines. Boosting with any available vaccine was better than not boosting. (Funded by the Netherlands Organization for Health Research and Development ZonMw; SWITCH number, NCT04927936.).

/immunology , Antibodies, Viral/blood , COVID-19 Vaccines/immunology , Immunization, Secondary , Immunogenicity, Vaccine , Immunoglobulin G/blood , /immunology , Adult , Antibodies, Neutralizing/blood , Female , Humans , Interferon-gamma/blood , Male , Middle Aged , SARS-CoV-2 , Single-Blind Method , T-Lymphocytes/immunology