Hi, I had gone through your question and understand your concerns.
Yes , flu vaccines like Vaxigrip, Agripal are available to vaccinate your baby.
Flu vaccines cause
antibodies to develop in the body about two weeks after
vaccination , so it is recommended to get vaccine at least 2 weeks before travel , and get a booster shot after 1-2 months of Ist dose , thereafter a single shot every year as long as protection required.
You should get him vaccinated before travel .
Regarding degree of protection it is not straight forward as it depends on a number of factor, like body's response to vaccine , similarity between circulating strains of
influenza virus, and vaccine strain , roughly there is 70-75 percent reduction in hospitalization due to flu in vaccinated individuals.
Moreover , all persons in family getting vaccinated in family is an additional protection for child.
Hope this answers your question. If you have additional questions then please do not hesitate in writing to us.
Wishing you and your child good health.