Does infection with Flu give me natural immunity? 

If you get flu your body makes antibodies, but only to the particular strain of flu that made you unwell. Sometimes this is at the price of having to endure a really unpleasant illness, that some people die from every year. Unfortunately natural immunity is limited to that one particular strain. A key feature of flu viruses is that they change over time, so as to be continually able to cause infection. As new strains appear, protection from past infection or previous vaccination becomes unreliable. Until vaccines are developed that provide broader protection (still a long way off), the most effective way of increasing your protection is to be vaccinated every year. Each year’s flu jab is formulated to provide up to date protection against the prevailing strains of flu.