Officials warned us that this year’s flu vaccine will not be as effective because they detected changes in the virus strain after the vaccine went into production.

Scientists have discovered that the strain of influenza they prepared for this year has mutated, making the vaccine they prepared less effective.The changes were found this September by the U.S Health Department, but by then it was too late, the virus H3N2 has already suffered mutations.

Why can`t experts develop a new vaccine?

Officials at the World Health Organization and the U.S Food and Drug Administration explained to us the process of making vaccines.

Every year they choose three or four strains of flu virus, found in South America, and they test for clues to what will possibly hit the U.S in the fall or winter season. Also experts say that examination of the virus can determine how fast the strain mutates, making the process even more difficult.

After careful examination of the respective strains, they produce the vaccine by February, so that mass production can begin in March. So the “process of making a vaccine is not something done over night”, as Dr.William Shaffner, an  infectious disease expert at Vanderbilt University School of Medicine, said in a official statement.

The vaccines are made by injecting fertilized chicken eggs with the strain virus. The main types of vaccine that can be administered are those who can protect against three or four strains of the virus.

Given the fact that the virus can mutate at any given time and rate, this could mislead experts in the production of the vaccine. While not being as effective as originally designed, the vaccine may still offer protection against other strains or lessen the symptoms during infection.

The main issue with this year’s strain, the H3N2, is that it has been associated with a higher mortality rate, even so, health officials still encourage people to get vaccinated.

Dr. Thomas Frieden, Director of CDC (U.S Centers of Disease Control and Prevention) said during a news conference: “ We continue to recommend flu vaccine as the single best way to protect yourself against the flu.”