Septic and Crystal-Induced Arthritis (Pseudogout) Post-COVID-19 Vaccination.

Severe acute respiratory syndrome coronavirus 2 infection has been a global public health crisis for the past two years. Vaccination has been a mainstay preventive approach among other strategies such as hand washing, social distancing, and wearing facemasks. Here, we present a case of concomitant calcium pyrophosphate deposition disease flare and septic arthritis of the right knee following coronavirus disease 2019 (COVID-19) booster vaccination in a 69-year-old African American male who presented with a painful swollen right knee with associated fever, chills, and rigors three days post-vaccination. Right knee synovial fluid aspirate appeared turbid with elevated white cell count, positive for both intra and extracellular calcium pyrophosphate crystals, and positive for beta-hemolytic group C. The swollen joint improved with right knee arthroscopic irrigation and intravenous antibiotics on admission. The patient subsequently completed a total of six weeks of antibiotics with clinical improvement and normalization of inflammatory markers. No reported incidence of gout or pseudogout post-COVID-19 vaccination has been reported despite reported cases of gout flares with other vaccines. Improper aseptic vaccination technique has been implicated as a possible cause of septic arthritis post-vaccination. Healthcare providers must discuss such adverse events with their patients prior to vaccine administration.