*2.4.2 Vaccine response and breakthroughs infection*

Davis et al. calculated the neutralisation capacity of BNT162b2 (Pfizer/BioNTech) and ChAdOx1 (Oxford/AstraZeneca) vaccines against the SARS-CoV-2 B.1.617.1 and B.1.617.2 lineages. Both B.1.617.1 and B.1.617.2 reduced antibody neutralisation by 4.31 and 5.11-fold in vaccine recipients, respectively. However, the neutralisation response was significantly higher in two doses of BNT162b2 vaccine recipients than in two doses of ChAdOx1 [55]. During a period of high Delta prevalence, Havers et al. found that hospitalisation rates in unvaccinated individuals were more than 10 times higher than in vaccinated recipients [75]. Twohig et al. found that the risk of hospitalisation or emergency care was higher in delta variant patients who were either unvaccinated or received the first dose (dose taken within 21 days) compared to that of alpha variant patients [24]. When compared to unvaccinated individuals, Veneti et al. showed a reduction in hospitalisation risk of 72 percent (95% CI 59–82%) and 76% (95% CI 61–85%) in partially or fully vaccinated individuals after adjusting for gender, age group, country of birth, variant, and underlying comorbidities [37].
