Abstract: Objective　To explore the therapeutic effect of nucleoside analogues (NAs) on reactivation of HBV in children with chronic hepatitis B virus (HBV) infection treated by chemotherapy or immunosuppressant, and to observe the preventive and therapeutic and preventive effect of antiviral drugs given before treatment on reactivation of HBV. Methods Forty-one children with chronic HBV infection who received chemotherapy or immunosuppressive therapy from January 2009 to December 2018 were selected as the study subjects. The children who had chemotherapy or immunosuppressant therapy but did not receive NAs prophylactic antiviral therapy were included into the control group. The children who started to use NAs 1~2 weeks before chemotherapy or immunosuppressive drugs and continued for at least 3 months were included into the prevention group. The reactivation of HBV and liver function were observed in two groups. Results　Among the 41 children, 18 had HBV reactivation, including 1 (6.3%) in the prevention group (n=16) and 17 (68.0%) in the control group (n=25), and the incidence of reactivation was significantly different between the two groups (χ2=18.72, P<0.001). In the prevention group, one child had HBV reactivation due to control use of NAs. In the control group, 11 children were treated with NAs after HBV reactivation, among whom 9 had decreased HBV DNA and 2 had increased HBV DNA after secondary infection. Conclusions　All children with chronic HBV infection who need chemotherapy or immunosuppressant should be routinely screened for HBV serological markers, HBV DNA and liver function before treatment. Prophylactic use of NAS before HBV reactivation and timely standardized use of NAs in children who have already had HBV reactivation are of great significance in reducing the occurrence of HBV reactivation, improving clinical prognosis, reducing HBV replication and reducing liver function damage.

Key words: 　chemotherapy;　immunosuppression;　hepatitis B virus;　reactivation;　child