Vaccine efficacy and duration of protection

If an individual did not develop high antibody titers after vaccination, should he/she be vaccinated again with another vaccine? Is it safe? What should be an interval between two vaccinations?

WHO does not recommend testing for antibodies after any routine or seasonal vaccination. Testing, if available, will significantly complicate the programme and increase its cost. It will also raise issues of the tests’ quality and may trigger rumors about quality and safety of vaccines. In addition, the post-vaccination protective immunity of vaccines depends not only on availability and quantity of virus-neutralizing antibodies, but also on cellular immunity.