Humoral response among patients with interstitial lung disease vaccinated with the BNT162b2 SARS-Cov-2 vaccine: a prospective cohort study.

Background: Patients with interstitial lung disease (ILD) are at high risk of severe COVID-19 infection. Additionally, their anti-inflammatory and antifibrotic treatment may cause immunosuppression. Nevertheless, their ability to mount an adequate immune response to messenger RNA SARS-CoV-2 vaccines was not evaluated. Therefore, we aimed to evaluate the humoral response after the BNT162b2 vaccine among idiopathic pulmonary fibrosis (IPF) patients treated with antifibrotic therapy and among non-IPF ILD patients treated with anti-inflammatory therapy.

Methods: We conducted an observational prospective cohort study to evaluate the level of anti-spike (S-IgG) antibodies after two doses of the BNT162b2 vaccine in patients with ILD. The cohort included 40 patients with idiopathic pulmonary fibrosis (IPF) treated with anti-fibrotic therapy and 29 patients with non-IPF ILD treated with anti-inflammatory therapy. For S-IgG titer measurement, one serology test was drawn from all patients 4-6 months after the second vaccine dose. In addition a control group matched for age and sex was created from a healthy control cohort of 107 patients. The study was conducted in Rabin Medical Center (Israel) between June and August 2021.

Results: All patients in the anti-fibrotic arm were seropositive (40/40), corresponding to the matched control group (P = 1.0). The anti-fibrotic arm had a significantly lower median antibody titer in comparison to the matched control group (361.10 [IQR, 207-811] AU/ml vs. 820.75 [IQR, 459-1313] AU/ml; P < 0.001). Only 48.3% (14/29) of patients in the anti-inflammatory arm were seropositive in comparison to 100% (29/29) in the healthy control group (P < 0.001). The anti-inflammatory arm had a significantly lower median antibody titer in comparison to the healthy control group (39.6 [IQR, 4.25-165] AU/ml vs. 970.1 [IQR, 505-1926] AU/ml; P < 0.001).

Conclusion: IPF patients treated with antifibrotic therapy mount an adequate immune response after 2 doses of the BNT162b2 vaccine, and maintain a 100% seropositivity rate 4-6 months after vaccination. However, their antibody titer was reduced in comparison to a healthy control group. Among patients with non-IPF ILD treated with anti-inflammatory therapy, 48% were seronegative 4-6 months after the second vaccine dose. Moreover, treatment with rituximab caused significant immunosuppression, even in comparison to other anti-inflammatory treatments.