Replies

"Based on both epidemiologic and in vitro studies, Guillon et al. hypothesized that group O individuals are more resistant to SARS-CoV due to ABO antibodies and could decrease the rate of infection throughout the population (292). The degree of protection, however, may be influenced by the ABO antibody titer, secretor status, and incidence of group O in the population. Studies with human anti-A showed effective blocking with higher-titer anti-A (≥1:256) only; low-titer anti-A was ineffective (292). The latter finding has implications for individuals in industrialized countries, who tend to have low ABO titers (89). A nonsecretor phenotype would also nullify viral neutralization, since virus transmitted from a nonsecretor lacks ABH expression."