Why Do I Need to Get the Flu Vaccine Every Year?

Developing an effective flu vaccine is extremely challenging for scientists because influenza strains are constantly changing and mutating. Each year several different strains of the virus are circulating the globe and medical researchers are challenged to determine the best way to protect people from this illness. Current researchers make a yearly vaccine by predicting which flu strains are most likely to thrive and manufacturing a vaccination against these three strains. There are two main limitations to these vaccinations which require the vaccines to be reproduced every year. These include our body’s response to the vaccinations and the constantly evolving nature of viruses.

The Body’s Response to Vaccination

After getting vaccinated it takes about two weeks before your body begins to produce antibodies to protect against the flu virus. Over time the antibodies created by the vaccines will have a reduced effect. After an entire year has passed from receiving immunity the antibody levels are often very low and offer little or no protection. This fact is what makes vaccinated seniors so likely to still contract the flu. Antibodies created by the vaccine will decline much more rapidly in the elderly, falling below the protective levels within the first four months.

The Flu Changes

The influenza virus changes its structure and its shape as it travels around the world and infects different types of people. Specifically there are eight RNA strands that make up the flu virus which are continuously mutating. This virus has two ways of mutating.

Antigenic Drift

The first, Antigenic drift, is when over time these mutations causes a slow evolution of the virus. Even though the changes occur slowly over time, they do happen often enough that the body’s immune system can’t recognize influenza from year to year.

Antigenic Shift

The second way the flu changes is with Antigenic shift, which occurs when an abrupt change in RNA results in significant changes to the flu virus’ components. In these cases a new type of the virus will suddenly appear. Usually two different flu strains will infect the same cell at the same time and cause a combined and new version of the virus. People will have little if any immunity to this new type even if they have received the season’s vaccination.

These mutations which happen during the flu season will make last year’s vaccination ineffective for the next year’s mutated version of the flu. Becoming immune to an earlier strand of the virus will not offer any protection for a new strand of the virus.

Why Get the Flu Vaccine?

Despite all the mutations that the flu virus goes through there are several benefits to getting the yearly flu vaccination. The vaccine offers:

• Protection for yourself and those around you from the flu
• Protection for our seniors and infants who cannot be vaccinated
• Assurance that if you do contract the flu, the side effects will be much more mild