Background:
Anti-tumour necrosis factor (TNF) drugs such as infliximab are associated with attenuated antibody responses after COVID-19 vaccination. It is unknown how infliximab impacts vaccine-induced serological responses against highly transmissible Omicron variants, which possess the ability to evade host immunity and are now the dominating variants causing current waves of infection.
Methods:
CLARITY IBD is a prospective, multicentre, observational cohort study investigating the impact of infliximab and vedolizumab on SARS-CoV-2 infection and vaccination in patients with inflammatory bowel disease (IBD). In the current work, the primary outcome was neutralising antibody responses against SARS-CoV-2 wild-type and Omicron BA.1 and BA.4/5 variants after three doses of COVID-19 vaccination in 1288 patients with IBD without prior COVID-19 infection, who were established on either infliximab (n=871) or vedolizumab (n=417). Cox proportional hazards models were constructed to investigate the risk of breakthrough infection in relation to neutralising antibody titres.
Findings:
Following three doses of COVID-19 vaccine, neutralising titre NT50 (half-inhibitory neutralising titre) was significantly diminished in patients treated with infliximab as compared to patients treated with vedolizumab, against wild-type (geometric mean [95% CI], 1990 [1781, 2223] vs 3212 [2780, 3712], p<0·0001), BA.1 (95·46 [82·80, 110·0] vs 599·1 [492·6, 728·6], p<0·0001) and BA.4/5 (30·73 [26·26, 35·96] vs 212·2 [177·0, 254·4], p<0·0001) variants. Breakthrough infection was significantly more frequent in patients treated with infliximab (13·66% [11·49%, 16·16%], 119/871) compared to patients treated with vedolizumab (6·95% [4·79%, 9·95%], 29/417, p=0·0004). Cox proportional hazards models of time to breakthrough infection after the third dose showed infliximab treatment to be associated with a higher hazard risk of 1·71 [1·08 to 2·71] p=0·022) compared to vedolizumab. Higher neutralising antibody titres against BA.4/5 were associated with a lower hazard risk and a longer time to breakthrough infection (HR 0·87 [0·79 to 0·95] p=0·0028).