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BackgroundDespite the availability of effective vaccines against coronavirus disease 2019 (Covid-19), the emergence of variant strains and breakthrough infections pose a challenging new reality. Booster vaccinations are needed to maintain vaccine-induced protection. MethodsENSEMBLE2 is an ongoing, randomized, double-blind, placebo-controlled, phase 3 pivotal trial including crossover vaccination after emergency authorization of Covid-19 vaccines. Adults aged [≥]18 years were randomized to receive Ad26.COV2.S or placebo as a primary dose plus a booster dose at two months. The primary endpoint was vaccine efficacy against the first occurrence of molecularly-confirmed moderate to severe-critical Covid-19 with onset [≥]14 days after booster vaccination in the per-protocol population. Key efficacy, safety, and immunogenicity endpoints were also assessed. ResultsThe double-blind phase enrolled 31,300 participants, 14,492 of whom received 2 doses and were evaluable for efficacy (per-protocol set, Ad26.COV2.S n=7484; placebo n=7008). Baseline demographics and characteristics were balanced. Vaccine efficacy was 75.2% (adjusted 95% CI, 54.6-87.3) against moderate to severe-critical Covid-19 and was similar against symptomatic infection (75.6% [55.5-99.9]). Efficacy was consistent across participants with and without comorbidities, and reached 93.7% (58.5-99.9) in the US. Vaccine efficacy against severe-critical Covid-19 was 100% (32.6-100.0; 0 vs 8 cases). The booster vaccine induced robust humoral responses and exhibited an acceptable safety profile. ConclusionsA homologous Ad26.COV2.S booster administered 2 months after primary single-dose vaccination in adults led to high vaccine efficacy, including against any symptomatic infection and SARS-CoV-2 variants prevalent during the study. (Funding: Janssen Research and Development and others; ENSEMBLE2 ClinicalTrials.gov number, NCT04614948.)
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OBJECTIVE: As per the requirement of Korean Food and Drug Administration, this post-marketing surveillance was conducted in Korea to evaluate the safety and reactogenicity of Poliorix(TM) following its introduction in 2006. METHODS: In this open, multicenter study, the vaccine was administered as per the current practice of Korean doctors and in reference to the guidebook by the Korean Pediatric Society and as indicated in the Korean label which was as follows - for primary vaccination three doses were given to infants at ages 2, 4 and 6 months whereas, for the booster dose a single dose was given to children aged 4-6 years. Safety data during this six year surveillance was collected using diary cards which were distributed to the parents to record adverse events. RESULTS: A total of 639 subjects were enrolled into the study. Of these, 617 subjects and 22 subjects received the vaccine as a primary and booster dose, respectively. At least one unsolicited symptom was reported in 11.4% (73/639) of the subjects during the 7-day follow-up period; upper respiratory tract infection (2.5%;16/639) was the most frequently reported unsolicited symptom. One subject reported at least one unsolicited symptom (gastroenteritis) of grade 3 intensity within the 31-day post-vaccination period. Approximately 1.7% (11/639) of subjects reported 13 serious adverse events (SAEs). All SAEs were resolved by the end of the study. CONCLUSION: In Korea, primary and booster vaccination with Poliorix(TM) was well-tolerated in healthy subjects when administered according to the prescribing information as part of routine clinical practice.