PPOIT-003LT Interim Analysis F1: Follow-on study of a multicentre, randomised, controlled trial (PPOIT-003) evaluating the long-term safety and efficacy of Probiotic and Peanut Oral Immunotherapy (PPOIT) compared with Oral Immunotherapy (OIT) alone and with placebo in peanut allergic individuals (PPOIT-003 Follow-On)