Department of International and Community Oral Health, Tohoku University Graduate School of Dentistry, 4-1, Seiryo-Machi, Aoba-Ku, Sendai, Miyagi, 980-8575, Japan.
Department of Preventive Medicine, Nagoya University Graduate School of Medicine, Aichi, Japan.
BMC Infect Dis. 2024 Jan 29;24(1):135. doi: 10.1186/s12879-024-09035-3.
Bivalent COVID-19 vaccines have been implemented worldwide since the booster vaccination campaigns of autumn of 2022, but little is known about their effectiveness. Thus, this study holistically evaluated the effectiveness of bivalent vaccines against infection in older adults in Japan.
We adopted the test-negative design using COVID-19 test data of individuals, aged ≥ 65 years, residing in three municipalities in Japan, who underwent tests in medical institutions between October 1 and December 30, 2022. Logistic regression analyses were conducted to estimate the odds of testing positive according to vaccination status. Vaccine effectiveness was defined as (1 - odds ratio) × 100%.
A total of 3,908 positive and 16,090 negative results were included in the analyses. Receiving a bivalent dose in addition to ≥ 2 monovalent doses was 33.6% (95% confidence interval [CI]: 20.8, 44.3%) more effective than receiving no vaccination, and 18.2% (95% CI: 9.4, 26.0%) more effective than receiving ≥ 2 monovalent doses but not receiving a bivalent vaccination. In addition, the effectiveness peaked at 14-20 days after administration and then gradually declined over time. Furthermore, a bivalent booster dose provided 18.6% (95% CI: 9.9, 26.5%) additional protection among those vaccinated with ≥ 2 monovalent doses, in the absence of a previous infection history. However, we did not find sufficient evidence of effectiveness of bivalent vaccines among previously infected older adults.
Bivalent vaccines are effective against COVID-19 infections among older adults without a history of infection.
自 2022 年秋季加强针接种运动以来，全球范围内已开始接种二价 COVID-19 疫苗，但对于其有效性知之甚少。因此，本研究全面评估了二价疫苗在日本老年人中预防感染的效果。
我们采用了测试阴性设计，使用了 2022 年 10 月 1 日至 12 月 30 日期间在日本三个市的医疗机构接受检测的年龄≥65 岁的个体的 COVID-19 检测数据。通过逻辑回归分析，根据接种状态估计检测阳性的几率。疫苗有效性定义为(1-比值比)×100%。
共有 3908 例阳性和 16090 例阴性结果纳入分析。与未接种疫苗相比，同时接种二价疫苗和≥2 剂单价疫苗的效果更好，有效率为 33.6%(95%置信区间[CI]：20.8%，44.3%)；与仅接种≥2 剂单价疫苗相比，有效率为 18.2%(95%CI：9.4%，26.0%)。此外，接种后 14-20 天效果达到峰值，随后逐渐下降。此外，在没有既往感染史的情况下，对于已接种≥2 剂单价疫苗的人群，二价加强针提供了 18.6%(95%CI：9.9%，26.5%)的额外保护。然而，我们没有发现二价疫苗在既往感染的老年人中具有足够的有效性证据。
二价疫苗对无感染史的老年人预防 COVID-19 感染有效。
