Division of Clinical Virology, Center for Infectious Diseases, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan.
Division of Clinical Virology, Center for Infectious Diseases, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe, Hyogo 650-0017, Japan.
J Infect Public Health. 2023 Jul;16(7):1064-1072. doi: 10.1016/j.jiph.2023.05.004. Epub 2023 May 6.
Omicron variants with immune evasion have emerged, and they continue to mutate rapidly, raising concerns about the weakening of vaccine efficacy, and the very elderly populations are vulnerable to Coronavirus Disease 2019 (COVID-19). Therefore, to investigate the effect of multiple doses of mRNA vaccine for the newly emerged variants on these populations, cross-neutralizing antibody titers were examined against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) variants, including BQ.1.1 and XBB.
Blood samples were taken from residents at four long-term care facilities in Hyogo prefecture, Japan (median age, 91 years), after 3rd (n = 67) and 4th (n = 48) mRNA vaccinations, from April to October 2022. A live virus microneutralization assay was performed to determine the neutralizing antibody titers in participants' sera.
After 3rd vaccination, cross-neutralizing antibody prevalence against conventional (D614G) virus, Delta, Omicron BA.2, BA.5, BA.2.75, BQ.1.1, and XBB were 100%, 97%, 81%, 51%, 67%, 4%, and 21%, respectively. After 4th vaccination, the antibody positivity rates increased to 100%, 100%, 98%, 79%, 92%, 31%, and 52%, respectively. The 4th vaccination significantly increased cross-neutralizing antibody titers against all tested variants.
The positivity rates for BQ.1.1 and XBB increased after 4th vaccination, although the titer value was lower than those of BA.5 and BA.2.75. Considering the rapid mutation of viruses and the efficacy of vaccines, it may be necessary to create a system that can develop vaccines suitable for each epidemic in consideration of the epidemic of the virus.
具有免疫逃逸能力的奥密克戎变异株不断出现并快速突变，引起人们对疫苗效力减弱的担忧，老年人尤其容易感染 2019 年冠状病毒病（COVID-19）。因此，为了研究针对新出现的变异株，多次接种 mRNA 疫苗对这些人群的效果，检测了针对严重急性呼吸系统综合征冠状病毒 2（SARS-CoV-2）变异株的交叉中和抗体滴度，包括 BQ.1.1 和 XBB。
2022 年 4 月至 10 月，在日本兵库县的四个长期护理设施中采集了 67 名和 48 名第 3 次（中位数年龄 91 岁）和第 4 次（中位数年龄 91 岁）mRNA 疫苗接种后的居民血液样本。使用活病毒微量中和试验来确定参与者血清中的中和抗体滴度。
第 3 次接种后，对常规（D614G）病毒、Delta、Omicron BA.2、BA.5、BA.2.75、BQ.1.1 和 XBB 的交叉中和抗体阳性率分别为 100%、97%、81%、51%、67%、4%和 21%。第 4 次接种后，抗体阳性率分别增加至 100%、100%、98%、79%、92%、31%和 52%。第 4 次接种明显增加了对所有测试变异株的交叉中和抗体滴度。
尽管 BQ.1.1 和 XBB 的滴度值低于 BA.5 和 BA.2.75，但第 4 次接种后，其阳性率增加。考虑到病毒的快速突变和疫苗的功效，可能需要建立一个系统，在考虑病毒流行的情况下，为每种流行病毒研发合适的疫苗。
