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Abstract: FR-PO034

COVID-19 Vaccination as a Trigger for Atypical Hemolytic Uremic Syndrome

Session Information

Category: Coronavirus (COVID-19)

  • 000 Coronavirus (COVID-19)


  • Bouwmeester, Romy N., Radboudumc, Nijmegen, Gelderland, Netherlands
  • Van Zuilen, Arjan D., University Medical Center Utrecht, Utrecht, Utrecht, Netherlands
  • Wetzels, Jack F., Radboudumc, Nijmegen, Gelderland, Netherlands
  • Van De Kar, Nicole, Radboudumc, Nijmegen, Gelderland, Netherlands

After introduction of COVID-19 vaccination, rare but severe thrombocytopenia-associated complications have been reported. Although several patients developed aHUS after COVID-19 infection, to date it is unknown if COVID-19 vaccination could trigger aHUS in pediatric and adult patients with a pathogenic complement variant.

Case Description

Here we present three adult and one pediatric aHUS patient (all with pathogenic C3 variants) who developed a total of 5 episodes of onset cq relapse of atypical hemolytic uremic syndrome (aHUS) at a median of 7 days (range 2-26) after mRNA based (Pfizer/BioNTech’s, BNT162b2) and adenoviral (AstraZeneca, ChAdOx1 nCoV-19) COVID-19 vaccination. Other aHUS triggering or explanatory events were absent in all patients. During eculizumab treatment, kidney function recovered in all but one adult. Eculizumab was discontinued after stabilization of kidney function and a median treatment duration of 12 weeks (2.5-15).


We identified COVID-19 vaccination, independent of the vaccine type, as a potential trigger for aHUS onset and relapse in pediatric and adult patients. We hypothesize that the synergistic effect of a local complement-amplifying condition and a pre-existing (pathogenic) complement genetic variant might cause conversion of a ‘normal’ pro-inflammatory state into an unrestrained overactivation of the alternative pathway. We advise clear patient instruction and routinely monitoring of serum creatinine, proteinuria, mechanical hemolytic anemia (MAHA) parameters, and blood pressure approximately 3-7 days after COVID-19 vaccination in patients with a previous episode of aHUS, and/or a proven (likely) pathogenic variant in complement protein(s), and who are not treated with complement inhibitory therapy (eculizumab/ravulizumab). In addition, aHUS should be included in the differential diagnosis of patients with vaccine-induced thrombocytopenia, especially if co-occuring with MAKA and acute kidney injury.