Evaluation of the immunogenicity of prime-boost vaccination with the replication-deficient viral vectored COVID-19 vaccine candidate ChAdOx1 nCoV-19
Authors:S.P. Graham et al.
Link to paper: https://www.biorxiv.org/content/10.1101/2020.06.20.159715v1
Key Words:vaccination, ChAdOx1 nCoV-19
A booster immunisation 28 days post prime vaccination slightly increases spike-peptide reactive CD4 and CD8 T cell numbers in pigs, but not in mice.
The booster immunisation enhanced binding antibody titers in BALB/c mice and pigs, with a concomitant significant increase in SARS-CoV-2 neutralising titres in pigs.
Immunogenicity of a single administration of the adenoviral vector expressing SARS-CoV-2 spike protein (ChAdOx1 nCoV-19) was demonstrated previously in macaques. Here, the effect of a booster administered 28 days post initial immunisation is determined in mice and pigs. The booster immunisation slightly increases spike-peptide reactive CD4 and CD8 T cell numbers in pigs, but not in mice. It did enhance the antibody responses, particularly in pigs, with a significant increase in SARS-CoV-2 neutralising titres.
Impact for SARS-CoV2/COVID19 research efforts
Develop a vaccine for SARS-CoV2/COVID19
In vitro study
In vivo study; BALB/c and CD1 mice, and pigs
Strengths and limitations of the paper
Novelty: A prime-boost strategy is more effective than a single dose of ChAdOx1 nCoV-19
Standing in the field:An increase in immune response is expected upon booster. Interestingly, the Moderna vaccine prime+booster has superior antibody titers, whereas ChAdOx1 nCoV-19 has superior cellular responses.
Appropriate statistics: Appropriate; ANOVA or a mixed-effects model were conducted to
compare responses over time and between vaccine groups at different time points post-vaccination.
Viral model used:Lentiviral-based SARS-CoV-2 pseudoviruses for neutralisation responses
SARS-CoV-2 isolate England-2 stocks also used for neutralisation responses
Translatability:ChAdOx1 nCoV-1 is in phase I clinical trials and already cGMP produced by AstraZeneca.
Main limitations: Authors have not demonstrated protection after prime and booster vaccine to a challenge of the pigs (not sure if possible) or at least the mice (with mouse-adapted SARS-CoV-2)
Low number of pigs.
No clear marking of significance in the figures.