Vaccine Alliance Aotearoa New Zealand and Malaghan Institute of Medical Research, PO Box 7060, Wellington 6242, New Zealand.
University of Otago, 2 Riccarton Ave, Christchurch 8011, New Zealand.
Vaccine. 2023 Aug 31;41(38):5535-5544. doi: 10.1016/j.vaccine.2023.07.051. Epub 2023 Jul 27.
The ability of a third dose of the Pfizer-BioNTech BNT162b2 SARS-CoV-2 vaccine to stimulate immune responses against subvariants, including Omicron BA.1, has not been assessed in New Zealand populations. Unlike many overseas populations, New Zealanders were largely infection naïve at the time they were boosted. This adult cohort of 298 participants, oversampled for at-risk populations, was composed of 29% Māori and 28% Pacific peoples, with 40% of the population aged 55+. A significant proportion of the cohort was obese and presented with at least one comorbidity. Sera were collected 28 days and 6 months post second vaccination and 28 days post third vaccination. SARS-CoV-2 anti-S IgG titres and neutralising capacity using surrogate viral neutralisation assays against variants of concern, including Omicron BA.1, were investigated. The incidence of SARS-CoV-2 infection, within our cohort, prior to third vaccination was very low (<6%). This study found a third vaccine significantly increased the mean SARS-CoV-2 anti-S IgG titres, for every demographic subgroup, by a minimum of 1.5-fold compared to titres after two doses. Diabetic participants experienced a greater increase (∼4-fold) in antibody titres after their third vaccination, compared to non-diabetics (increase of ∼ 2-fold). This corrected for the deficiency in antibody titres within diabetic participants which was observed following two doses. A third dose also induced a neutralising response against Omicron variant BA.1, which was absent after two doses. This neutralising response improved regardless of age, BMI, ethnicity, or diabetes status. Participants aged ≥75 years consistently had the lowest SARS-CoV-2 anti-S IgG titres at each timepoint, however experienced the greatest improvement after three doses compared to younger participants. This study shows that in the absence of prior SARS-CoV-2 infection, a third Pfizer-BioNTech BNT162b2 vaccine enhances immunogenicity, including against Omicron BA.1, in a cohort representative of at-risk groups in the adult New Zealand population.
第三剂辉瑞-生物科技公司的 BNT162b2 SARS-CoV-2 疫苗刺激针对亚变种（包括奥密克戎 BA.1）的免疫反应的能力尚未在新西兰人群中进行评估。与许多海外人群不同，新西兰人在接受加强针时主要是没有感染过的。这项由 298 名参与者组成的成人队列，对高危人群进行了超额采样，其中 29%为毛利人，28%为太平洋岛民，40%的人群年龄在 55 岁以上。该队列的相当一部分人肥胖，并患有至少一种合并症。在第二次接种后 28 天和 6 个月以及第三次接种后 28 天采集血清。使用针对关注变种（包括奥密克戎 BA.1）的替代病毒中和测定法，研究了 SARS-CoV-2 抗-S IgG 滴度和中和能力。在第三次接种疫苗之前，我们队列中 SARS-CoV-2 感染的发生率非常低（<6%）。这项研究发现，与两剂相比，第三剂疫苗使每个人群亚组的 SARS-CoV-2 抗-S IgG 滴度至少增加了 1.5 倍，这显著增加了疫苗接种效果。与非糖尿病患者相比，糖尿病患者在第三次接种后抗体滴度增加了约 4 倍（增加了约 2 倍）。这纠正了两剂疫苗后观察到的糖尿病患者抗体滴度不足的情况。第三剂还诱导了对奥密克戎变异体 BA.1 的中和反应，而在两剂后则没有这种中和反应。无论年龄、BMI、种族或糖尿病状况如何，这种中和反应都有所改善。≥75 岁的参与者在每个时间点的 SARS-CoV-2 抗-S IgG 滴度始终最低，但与年轻参与者相比，在接受三剂后，他们的改善最大。这项研究表明，在没有先前 SARS-CoV-2 感染的情况下，第三剂辉瑞-生物科技公司的 BNT162b2 疫苗增强了免疫原性，包括对奥密克戎 BA.1 的免疫原性，这在新西兰成年高危人群的队列中得到了体现。
