Study aim: Comparing safety and serological response following homologous vs. heterologous COVID-19 booster vaccine in patients receiving autologous hematopoietic stem cell transplants(AHSCT) Design: This is a phase 2-3 double-blind, randomized controlled clinical trial to compare the serological response of the homologous COVID-19 vaccine versus the heterologous booster dose in 90 adult patients receiving AHSCT. For randomization, a balanced block randomization list was generated using the research institute's Web-based software, after entering the sample size and number of each block. Settings and conduct: Eligible adult patients receiving AHSCT in a research institute for oncology, hematology, and cell therapy, will be invited four weeks (±7 days) after the 2nd dose. After obtaining the written informed consent, COVID-19 rapid test and antibody titer test will be performed, afterward, the national code enter into the system, and the vaccine code will be announced. The vaccine will be injected. Antibody titer and Side effects are evaluated four weeks (±7 days) after the vaccination. Participants/Inclusion and exclusion criteria: Inclusion criteria: Age: 18-70 Time interval: 6 to 12 months after AHSCT Receiving two doses of Pastocovac vaccine, Exclusion criteria: Relapse of underlying disease Intervention groups: Group A is a homologous vaccine (Pastocovac), and group B is a heterologous vaccine (Sinopharm ). In both groups, the rapid COVID-19 test will be performed, and then the blood sample will be tested to measure the COVID-19 antibody titer. The patient will randomly receive the vaccine, and after four weeks (±7 days), the patient's blood sample will test for antibody titer, and the vaccine's side effects will be recorded. Main outcome variables: SARS-CoV-2 Anti SPIKE IgG titer three weeks (±7 days) following homologous versus heterologous booster vaccine