Ideally your should take full course of the rabies vaccine because rabies has not cure but it is an easily preventable disease. No need to worry about having covid or any other flu or fever interfering with the rabies vaccine. Taking the risk of getting rabies is too high to skip the vaccine for any fever. Consult your treating doctor regarding the fever also. He should know in detail about your health.
Next Steps
Complete rabies vaccine course.
Health Tips
Rabies vaccines are of different kind with various schedules. Follow the full course the vaccine that you have started.