Centre for Virus Research, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya,; Institute of Tropical Medicine, Nagasaki University, P.O. Box 19993-00202, Nairobi, Kenya,.
Department of Project Planning and Management, Mitsubishi Tanabe Pharma Corporation, 1-1-1, Marunouchi Chiyoda-ku, Tokyo 100-8205, Japan.
Vaccine. 2024 Sep 17;42(22):126210. doi: 10.1016/j.vaccine.2024.126210. Epub 2024 Aug 15.
Kenya introduced a monovalent rotavirus vaccine administered orally at 6 and 10 weeks of age into her National Immunization Program in July 2014. The study evaluated the long-term impact of the vaccine on hospitalization for all-cause and rotavirus-specific acute gastroenteritis (AGE) and strain epidemiology in Kenya.
Data on all-cause and rotavirus-specific AGE and strain distribution were derived from an eleven-year hospital-based surveillance of AGE among children aged <5 years at Kiambu County Teaching and Referral Hospital (KCTRH) in Central Kenya between 2009 and 2020. Fecal samples were screened for group A rotavirus using ELISA and genotyped using multiplex semi-nested RT-PCR. Trends in all-cause and rotavirus-related AGE and strain distribution were compared between the pre-vaccine (July 2009-June 2014), early post-vaccine (July 2014-June 2016) and late post-vaccine (February 2019-October 2020) periods.
Rotavirus-specific AGE was detected at 27.5% (429/1546, 95% CI: 25.5-30.1%) in the pre-vaccine period; 13.8% (91/658, 95% CI: 11.3-16.6%) in the early post-vaccine period (July 2014-June 2016); and 12.0% (229/1916, 95% CI: 10.6-13.5%) in the late post-vaccine period (February 2019-October 2020). This amounted to a decline of 49.8% (95% CI: 34.6%-63.7%) in rotavirus-specific AGE in the early post-vaccine period and 53.4% (95% CI: 41.5-70.3%) in the late post-vaccine period when compared to the pre-vaccine period. All-cause AGE hospitalizations declined by 40.2% (95% CI: 30.8%-50.2%) and 75.3% (95% CI: 65.9-83.1%) in the early post-vaccine and late post-vaccine periods, respectively, when compared to the pre-vaccine period. G3P [8] was the predominant strain in the late post-vaccine period, replacing G1P[8] which had predominated in the pre-vaccine and early post-vaccine periods. Additionally, we detected considerable proportions of uncommon strains G3P[6] (4.8%) and G12P[6] (3.5%) in the post-vaccine era.
Rotavirus vaccination has resulted in a significant decline in all-cause and rotavirus-specific AGE, and thus, provides strong evidence for public health policy makers in Kenya to support the sustained use of the rotavirus vaccine in routine immunization. However, the shift in strain dominance and age distribution of rotavirus AGE in the post-vaccine era underscores the need for continued surveillance to assess any possible vaccine-induced selective pressure that could diminish the vaccine effectiveness over time.
肯尼亚于 2014 年 7 月将单价轮状病毒疫苗纳入国家免疫计划，以 6 周和 10 周龄的婴儿为接种对象。本研究评估了该疫苗对肯尼亚所有病因和轮状病毒特异性急性胃肠炎（AGE）住院的长期影响，以及该疫苗对肯尼亚轮状病毒的流行病学影响。
本研究基于 2009 年至 2020 年期间肯尼亚中部基安布县教学和转诊医院（KCTRH）以 5 岁以下儿童为对象的基于医院的急性胃肠炎（AGE）的 11 年监测数据，研究人员对所有病因和轮状病毒特异性 AGE 以及轮状病毒株分布情况进行了分析。采用 ELISA 检测粪便样本中的轮状病毒，并采用多重半巢式 RT-PCR 进行基因分型。本研究比较了疫苗接种前（2009 年 7 月至 2014 年 6 月）、疫苗早期（2014 年 7 月至 2016 年 6 月）和疫苗后期（2019 年 2 月至 2020 年 10 月）三个时期的所有病因相关 AGE 和轮状病毒相关 AGE 以及轮状病毒株分布情况。
疫苗接种前、疫苗早期和疫苗后期轮状病毒特异性 AGE 的检出率分别为 27.5%（429/1546，95%CI：25.5%-30.1%）、13.8%（91/658，95%CI：11.3%-16.6%）和 12.0%（229/1916，95%CI：10.6%-13.5%）。与疫苗接种前相比，疫苗早期和疫苗后期轮状病毒特异性 AGE 分别下降了 49.8%（95%CI：34.6%-63.7%）和 53.4%（95%CI：41.5%-70.3%）。与疫苗接种前相比，所有病因 AGE 住院分别下降了 40.2%（95%CI：30.8%-50.2%）和 75.3%（95%CI：65.9%-83.1%）。在疫苗接种后期，G3P[8]取代了 G1P[8]，成为主要流行株，而 G1P[8]在疫苗接种前和疫苗早期是主要流行株。此外，我们还在疫苗接种后时期检测到相当比例的不常见株 G3P[6]（4.8%）和 G12P[6]（3.5%）。
轮状病毒疫苗接种显著降低了所有病因和轮状病毒特异性 AGE，这为肯尼亚公共卫生政策制定者提供了有力证据，支持在常规免疫中持续使用轮状病毒疫苗。然而，轮状病毒 AGE 在疫苗接种后时期的流行株优势和年龄分布的变化，突显了需要持续监测，以评估任何可能因疫苗接种而导致的选择性压力变化，这种压力可能会随着时间的推移降低疫苗的有效性。
