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Abstract: TH-PO937

Humoral Response After Three Doses of SARS-CoV-2 Vaccines in Hemodialysis Patients

Session Information

Category: Coronavirus (COVID-19)

  • 000 Coronavirus (COVID-19)

Authors

  • Trigo, Filipa, Centro Hospitalar do Medio Tejo EPE, Torres Novas, Santarem, Portugal
  • Duarte, Rui A., Centro Hospitalar do Medio Tejo EPE, Torres Novas, Santarem, Portugal
  • Lopes, Karina, Centro Hospitalar do Medio Tejo EPE, Torres Novas, Santarem, Portugal
  • Luz, Ivan Andrade, Centro Hospitalar do Medio Tejo EPE, Torres Novas, Santarem, Portugal
  • Santos, Paulo A., Centro Hospitalar do Medio Tejo EPE, Torres Novas, Santarem, Portugal
Background

Hemodialysis patients (HDP) are at higher risk of exposing and developing severe coronavirus disease 2019 (COVID-19). To protect this population, the Portuguese government implemented an early vaccination of these patients in the national COVID-19 immunization plan. Nevertheless, the humoral response to the two doses of BNT162b2 on HDP was lower than the one expected in the general population, leading us to believe that a third dose is of high importance at this group of patients. This study aims to determine the humoral response to the third dose of SARS-CoV-2 mRNA vaccine.

Methods

A single center observational prospective study was conducted following HDP receiving SARS-CoV-2 mRNA vaccines in a Portuguese center. Specific anti-Spike IgG quantification 3 weeks after first and second doses, and 3 months after the third dose, was used to determine absolute values and non-responders (NR).

Results

A total of 59 patients were enrolled in this study, 33.4% of them were female and the median age was 71.3 years old. About 44% of the patients had COVID-19, all of them after the immunization with two doses of BNT162b2 vaccine. All of them suffered from mild to moderate disease. The median IgG anti-Spike S1 level after the second dose was 43.71AU/mL, with an IQR of 53, whereas 3 months after the third dose was of 473.5AU/mL, with an IQR of 1403.8 (Figure 1). The rate of NR (IgG anti-Spike S1 levels <1AU/mL) also had a high variation with the number of the doses administrated - 14% of the patients after the second dose versus 0% after the third dose. After the last immunization, only 20% of the patients remained weak responders (IgG anti-Spike S1 < 150AU/mL). Age, sex, hemoglobin, ferritin, parathyroid hormone (PTH), C-Reactive Protein (CPR) and albumin did not impact on the response to the vaccine.

Conclusion

Most of HDP responded strongly to the third dose of SARS-CoV-2 vaccine, even though the IgG anti-Spike levels were only measured 3 months after the administration. There is no analytical feature that can predict the response to the vaccine. Therefore, every hemodialysis patient would benefit from the administration of a third vaccine dose at least six months after receiving the second one.