Vaccine hesitation refers to the refusal or delay of vaccination when vaccination services are available and is one of the top ten threats to global health. Vaccine hesitation varies in different countries，and its influencing factors are very complex.However，domestic research on this phenomenon is still in its infancy.This article reviews the phenomenon of vaccine hesitation，the occurrence and influencing factors of vaccine hesitation in some developed countries since the 21st century，to provide the basis for taking effective measures for the phenomenon of vaccine hesitation in China.

Objective:To investigate the correlation between the lipocalin-2 (LCN-2) level and white matter hyperintensities (WMHs) in patients with ischemic stroke.Methods:Consecutive patients with ischemic stroke admitted to the Department of Neurology, Jinling Hospital, Medical School of Nanjing University from September 2021 to November 2021 and whose duration from onset to hospitalization <14 d were prospectively enrolled. Enzyme-linked immunosorbent assay was used to detect the serum LCN-2. Fazekas scale was used to assess the severity of periventricular and subcortical WMHs. A total WMHs score ≥3 was defined as severe WMHs. Multivariate logistic regression analysis was used to determine the correlation between serum LCN-2 level and WMHs. Results:A total of 179 patients were enrolled, including 122 males (68.2%), aged 64.7±11.6 years. The median serum LCN-2 level was 387.1 g/L, and 86 patients (48.0%) had severe WMHs. Serum LCN-2 in the severe WMH group was significantly higher than that in the non-severe WMH group (505.3±342.4 g/L vs. 367.8±224.5 g/L; t=3.110, P=0.002). Multivariable logistic regression analysis showed that after adjusting for the relevant confounding factors, there was a significant correlation between higher serum LCN-2 and severe WMHs (odds ratio 2.32, 95% confidence interval 1.17-4.63; P=0.017) and higher total WMHs score (odds ratio 1.62, 95% confidence interval 1.12-2.35; P=0.011). Conclusion:Higher serum LCN-2 level is associated with severe WMHs in patients with ischemic stroke.