ABSTRACT
Since the emergence of SARS-CoV-2, humans have been exposed to distinct SARS-CoV-2 antigens, either by infection with different variants, and/or vaccination. Population immunity is thus highly heterogeneous, but the impact of such heterogeneity on the effectiveness and breadth of the antibody-mediated response is unclear. We measured antibody-mediated neutralisation responses against SARS-CoV-2 Wuhan, SARS-CoV-2a, SARS-CoV-2d and SARS-CoV-2o pseudoviruses using sera from patients with distinct immunological histories, including naive, vaccinated, infected with SARS-CoV-2 Wuhan, SARS-CoV-2a or SARS-CoV-2d, and vaccinated/infected individuals. We show that the breadth and potency of the antibody-mediated response is influenced by the number, the variant, and the nature (infection or vaccination) of exposures, and that individuals with mixed immunity acquired by vaccination and natural exposure exhibit the broadest and most potent responses. Our results suggest that the interplay between host immunity and SARS-CoV-2 evolution will shape the antigenicity and subsequent transmission dynamics of SARS-CoV-2, with important implications for future vaccine design.
Subject(s)
Severe Acute Respiratory SyndromeABSTRACT
We present a comprehensive analysis of antibody and cellular responses in children aged 12-16 years who received COVID-19 vaccination with ChAdOx1 (n=6) or mRNA vaccine (mRNA-1273 or BNT162b2, n=9) using a 12-week extended-interval schedule. mRNA vaccination of seropositive children induces high antibody levels, with one dose, but a second dose is required in infection-naïve children. Following a second ChAdOx1 dose, antibody titres were higher than natural infection, but lower than mRNA vaccination. Vaccination induced live virus neutralising antibodies against Alpha, Beta and Delta variants, however, a second dose is required in infection-naïve children. We found higher T-cell responses following mRNA vaccination than ChAdOx1. Phenotyping of responses showed predominantly early effector-memory CD4 T cell populations, with a type-1 cytotoxic cytokine signature, with IL-10. These data demonstrate mRNA vaccination induces a co-ordinated superior antibody and robust cellular responses in children. Seronegative children require a prime-boost regime for optimal protection.
Subject(s)
COVID-19ABSTRACT
Background: Immune suppression is a clinical feature of chronic lymphocytic leukaemia (CLL) and patients show increased vulnerability to SARS-CoV-2 infection and suboptimal antibody responses.Method: We studied antibody responses in 500 patients following dual COVID-19 vaccination to assess the magnitude, correlates of response, stability and functional activity of the spike-specific antibody response with 2 different vaccine platforms.Results: Spike-specific seroconversion post-vaccine was seen in 67% of patients compared to 100% of age-matched controls. Amongst responders, titres were 3.7 times lower than the control group. Antibody responses showed a 33% fall over the next 4 months. The use of an mRNA (n=204) or adenovirus-based (n=296) vaccine platform did not impact on antibody response. Male gender, BTKi therapy, prophylactic antibiotics use and low serum IgA/IgM were predictive of failure to respond. Antibody responses after CD20-targeted immunotherapy recovered 12 months-post treatment. Post-vaccine sera from CLL patients with Spike-specific antibody response showed markedly reduced neutralisation of the SARS-CoV-2 delta variant compared to healthy controls. Patients with previous natural SARS-CoV-2 infection showed equivalent antibody levels and function as healthy donors after vaccination.Interpretation: These findings demonstrate impaired antibody responses following dual COVID-19 vaccination in patients with CLL and further define patient risk groups. Furthermore, humoral protection against the globally-dominant delta variant is markedly impaired in CLL patients and indicates the need for further optimisation of immune protection in this patient cohort.Funding Information: This work was partially supported by the UK Coronavirus Immunology Consortium (UK-CIC) funded by DHSC/UKRI and the National Core Studies Immunity programme.Declaration of Interests: The authors declare no conflicts of interest.Ethics Approval Statement: Informed consent was obtained by remote consultation and work performed under the CIA UPH IRAS approval (REC 20\NW\0240) from North-West and Preston ethics committee and conducted according to the Declaration of Helsinki.