Mucosal antibody response and SARS-CoV-2 shedding in patients with
COVID-19 related olfactory dysfunction
Abstract
Olfactory dysfunction was one of the most common symptom of infection
with the Wuhan strain of SARS-CoV-2 and could persist for several months
after symptom onset. The pathogenesis of prolonged olfactory dysfunction
(OD) remains poorly understood but probably involves sustained viral
replication associated with limited mucosal immune response to the
virus. This prospective study was conducted to investigate the potential
relationship between nasal SARS-CoV-2 viral load and antibody levels in
patients with loss of smell. One hundred and five patients were
recruited 2 weeks after presenting with confirmed COVID-19 associated
OD. Based on the identification sniffing test performed at enrollment,
52 patients were still anosmic or hyposmic and 53 were normosmic.
SARS-CoV-2 was detectable in nasal wash of about 50% of anosmic and
normosmic patients. Higher viral load was detected in anosmic patients
with lower levels of SARS-CoV-2 specific nasal IgG and IgA. This
association was not observed in normosmic patients. No relationship
between nasal viral load and antibodies to endemic coronaviruses was
observed. SARS-CoV-2 replication in the nasal cavity may be promoted by
defective mucosal antibody responses in patients with OD. Boosting
mucosal immunity may limit nasal SARS-CoV-2 replication and thereby help
in the control of persistent OD.