Stable Levels of Antibodies Against Unrelated Toxoid Vaccines After COVID-19: COVID-19 Infection Does Not Affect Toxoid Vaccine Antibody Levels.

BACKGROUND

Lymphopenia is common in COVID-19. This has raised concerns that COVID-19 could affect the immune system akin to measles infection, which causes immune amnesia and a reduction in protective antibodies.

METHODS

We recruited COVID-19 patients (n = 59) in Helsinki, Finland, and collected plasma samples on 2 to 3 occasions during and after infection. We measured IgG antibodies to diphtheria toxin, tetanus toxoid, and pertussis toxin, along with total IgG, SARS-CoV-2 spike protein IgG, and neutralizing antibodies. We also surveyed the participants for up to 17 months for long-term impaired olfaction as a proxy for prolonged post-acute COVID-19 symptoms.

RESULTS

No significant differences were found in the unrelated vaccine responses while the serological response against COVID-19 was appropriate. During the acute phase of the disease, the SARSCoV-2 IgG levels were lower in outpatients when compared to inpatients. SARS-CoV-2 serology kinetics matched expectations. In the acute phase, anti-tetanus and anti-diphtheria IgG levels were lower in patients with prolonged impaired olfaction during follow up than in those without.

CONCLUSIONS

We could not detect significant decline in overall humoral immunity during or after COVID-19 infection. In severe COVID-19, there appears to be a temporary decline in total IgG levels.