Abstract
Background: Protection offered by coronavirus disease 2019 (COVID-19) vaccines wanes over time, requiring an evaluation of different boosting strategies to revert such a trend and enhance the quantity and quality of Spike-specific humoral and cellular immune responses. These immunological parameters in homologous or heterologous vaccination boosts have thus far been studied for mRNA and ChAdOx1 nCoV-19 vaccines, but knowledge on individuals who received a single dose of Ad26.COV2.S is lacking.
Methods: We studied Spike-specific humoral and cellular immunity in Ad26.COV2.S-vaccinated individuals (n = 55) who were either primed with Ad26.COV2.S only (n = 13) or were boosted with a homologous (Ad26.COV2.S, n = 28) or heterologous (BNT162b2, n = 14) second dose. We compared our findings with the results found in individuals vaccinated with a single (n = 16) or double (n = 44) dose of BNT162b2.
Findings: We observed that a strategy of heterologous vaccination enhanced the quantity and breadth of both Spike-specific humoral and cellular immunity in Ad26.COV2.S-vaccinated individuals. In contrast, the impact of the homologous boost was quantitatively minimal in Ad26.COV2.S-vaccinated individuals, and Spike-specific antibodies and T cells were narrowly focused to the S1 region.
Conclusions: Despite the small sample size of the study and the lack of well-defined correlates of protection against COVID-19, the immunological features detected support the utilization of a heterologous vaccine boost in individuals who received Ad26.COV2.S vaccination.
Funding: This study is partially supported by the Singapore Ministry of Health’s National Medical Research Council under its COVID-19 Research Fund (COVID19RF3-0060, COVID19RF-001, and COVID19RF-008), The Medical College St. Bartholomew’s Hospital Trustees – Pump Priming Fund for SMD COVID-19 Research.
Keywords: Adenovirus vector; COVID-19; antiviral immunity; heterologous immunity; vaccines.
【저자키워드】 COVID-19, Vaccines, heterologous immunity, antiviral immunity, Adenovirus Vector, 【초록키워드】 coronavirus disease, Coronavirus disease 2019, Vaccine, vaccination, Antiviral, Vaccines, T cells, knowledge, protection, Adenovirus, BNT162b2, T cell, Ad26.COV2.S, cellular immunity, mRNA, immune responses, Singapore, antiviral immunity, utilization, homologous, ChAdOx1, ChAdOx1 nCoV-19, Heterologous, boost, single dose, specific antibodies, breadth, dose, heterologous vaccine, humoral, Medical Research Council, Support, second dose, individual, quantity, Ad26, cellular immune responses, small sample size, college, COV2.S, spike-specific antibodies, pump, Spike-specific antibody, SMD, Ministry of Health, immunological, feature, ENhance, lack, supported, individuals, homologous or heterologous, immunological parameter, of BNT162b2, offered, Trustee, 【제목키워드】 homologous, boost, Ad26.COV2.S vaccine, recipient,