A 76-year-old woman with stable RA developed malaise and a high-grade fever (>39.0 C) 5 days after receiving a second dose of BNT162b2 mRNA vaccine. Ten days after vaccination, she developed a persistent cough and dyspnea. Seventeen days after vaccination, she was admitted to another hospital because of persistent fever. Blood tests showed a white blood cell (WBC) count of 4990/muL and lactate dehydrogenase (LDH) and C-reactive protein (CRP) levels of 477 U/L and 6.4 mg/dL, respectively. Although the antigen test for SARS, serum B-D glucan, and blood culture was negative, tests for Mycoplasma, Chlamydia, and sputum culture were not examined. Chest computed tomography (CT) showed infiltration and ground glass opacites (GGOs) in all lung fields (Figure 1(a)). The patient was provisionally diagnosed with interstitial lung disease (ILD) and was transferred to our hospital 21 days after vaccination.
Prior to the onset of her symptoms, the patient's RA had been stable on methotrexate treatment (12 mg/week), which she had taken for 15 years.
On admission, her body temperature, blood pressure, pulse, respiratory rate, and SpO2 were 36.5 C, 110/60 mmHg, 65 beats/min, 18 breaths/min, and 98% (in room air), respectively. Her arthritis was stable and showed no changes of note since a previous check-up one month earlier. The results of blood tests were as follows: WBC, 5420/muL; red blood cells (RBC), 377 x 104/muL; hemoglobin (Hb), 11.2 g/dL; hematocrit, 35.5%; platelets, 40.4 x 104/muL; CRP 1.47 mg/dL; LDH, 311 U/L; Krebs von den Lungen-6 (KL-6), 452.4 U/mL; and surfactant protein D (SP-D), 226 ng/mL. Her rheumatoid factor, anti-cyclic citrullinated peptide antibody, and antinuclear antibody were negative.
Tests for Mycoplasma, Chlamydia, and tuberculosis (T-Spot), and antigen tests for Cryptococcus, Candida, Aspergillus, cytomegalovirus antigen, and SARS-CoV-2 antigen were negative. Serum beta-D glucan, blood culture, and polymerase chain reaction testing of respiratory samples for Pneumocystis jirovecii DNA were also negative. Chest CT showed a significant improvement compared to the chest CT performed 4 days earlier (Figure 1(b)). The patient was treated conservatively and did not receive antibiotics or immunosuppressive drugs during hospitalization. Her cough, dyspnea, and fever resolved spontaneously, and she was discharged from hospital after 7 days. Her final diagnosis was transient pneumonitis induced by a COVID-19 mRNA vaccine. At the 3-month follow-up, she had not experienced a relapse of pneumonitis and her blood test results had improved: CRP, 0.06 mg/dL (from 1.47 mg/dL); LDH, 189 U/L (from 311 U/L); KL-6, 165.1 U/mL (from 452.4 U/mL); and SP-D, 102 ng/mL (from 226 ng/mL).