Antibodies to the RBD of SARS‐CoV‐2 Wuhan (WT) virus and the variants of concern by the haemagglutination test (HAT). (a) Antibodies to the RBD were measured by HAT in previously uninfected individuals at 4 weeks (n = 62) and at 6 weeks (n = 58), and in individuals who were naturally infected (n = 36) for the WT, alpha variant, beta variant and delta. (b) Antibodies to the RBD were also measured by HAT in previously infected individuals (n = 33), at 4 and 6 weeks to WT, alpha, beta and delta. The ACE2 receptor blocking antibody titres, were correlated with the HAT titre to the WT (Spearman's r = 0.67, p < 0.0001).The differences in HAT titres to WT and variants in baseline uninfected and infected individuals were assessed by the Wilcoxon matched pairs signed ranked test. All tests were two sided. the error bars indicate the median and the interquartile ranges. Green: WT; red: Alpha; orange: Beta; blue: Delta