Association between antibody responses post-vaccination and severe COVID-19 outcomes in Scotland
Macdonald C., Palmateer N., McAuley A., Lindsay L., Hasan T., Hameed SS., Hall E., Jeffrey K., Grange Z., Gousias P., Mavin S., Jarvis L., Cameron JC., Daines L., Tibble H., Simpson CR., McCowan C., Katikireddi SV., Rudan I., Fagbamigbe AF., Ritchie L., Swallow B., Moss P., Robertson C., Sheikh A., Murray J.
Several population-level studies have described individual clinical risk factors associated with suboptimal antibody responses following COVID-19 vaccination, but none have examined multimorbidity. Others have shown that suboptimal post-vaccination responses offer reduced protection to subsequent SARS-CoV-2 infection; however, the level of protection from COVID-19 hospitalisation/death remains unconfirmed. We use national Scottish datasets to investigate the association between multimorbidity and testing antibody-negative, examining the correlation between antibody levels and subsequent COVID-19 hospitalisation/death among double-vaccinated individuals. We found that individuals with multimorbidity (≥ five conditions) were more likely to test antibody-negative post-vaccination and 13.37 [6.05–29.53] times more likely to be hospitalised/die from COVID-19 than individuals without conditions. We also show a dose-dependent association between post-vaccination antibody levels and COVID-19 hospitalisation or death, with those with undetectable antibody levels at a significantly higher risk (HR 9.21 [95% CI 4.63–18.29]) of these serious outcomes compared to those with high antibody levels.