Reduced neutralisation of the Delta (B.1.617.2) SARS-CoV-2 variant of concern following vaccinationDavis, C., Logan, N., Tyson, G., Orton, R., Harvey, W., Haughney, J., Perkins, J., The COVID-19 Genomics UK (COG-UK) Consortium, , Peacock, T., Barclay, W. S., Cherepanov, P., Palmarini, M., Murcia, P. R., Patel, A. H., Robertson, D. L., Thomson, E. C., Willett, B. J.10.1101/2021.06.23.21259327 — Posted: 2021-06-28
Vaccines are proving to be highly effective in controlling hospitalisation and deaths associated with SARS-CoV-2 infection but the emergence of viral variants with novel antigenic profiles threatens to diminish their efficacy. Neutralising antibody titres elicited by vaccination with two doses of BNT162b2 were significantly higher than those elicited by vaccination with two doses of ChAdOx1. Fold decreases in the magnitude of neutralisation titre following two doses of BNT162b2, conferred reductions in titre of 7.77, 11.30 and 9.56-fold respectively to B.1.617.1, B.1.617.2 and B.1.351 pseudoviruses, the reduction in neutralisation of the delta variant B.1.617.2 surpassing that of B.1.1351. Fold changes in those vaccinated with two doses of ChAdOx1 were 0.69, 4.01 and 1.48 respectively.
Mix and Match
Strong immunogenicity of heterologous prime-boost immunizations with the experimental vaccine GRAd-COV2 and BNT162b2 or ChAdOx1-nCOV19Agrati, C., Capone, S., Castilletti, C., Cimini, E., Matusali, G., Meschi, S., Tartaglia, E., Camerini, R., Lanini, S., Milleri, S., Colloca, S., Vitelli, A., Folgori, A.10.1101/2021.06.22.21258961 — Posted: 2021-06-28
Here we report on the humoral and cellular immune response in eight volunteers who autonomously chose to adhere to the Italian national COVID-19 vaccination campaign more than 3 months after receiving a single administration GRAd-COV2 vaccine candidate in the context of the phase 1 clinical trial. We observed a clear boost of both binding/neutralizing antibodies as well as T cell responses upon receipt of the heterologous BNT162b2 or ChAdOx1-nCOV19 vaccines. These results, despite the limitation of the small sample size, support the concept that a single-dose of an adenoviral vaccine may represent an ideal tool to effectively prime a balanced immune response, which can be boosted to high levels by a single dose of a different vaccine platform.