Why do you have to take the influenza shots annually ?

Vaccines for many diseases like measles, mumps and rubella, chicken pox, hepatitis and pneumonia offer a lifetime of protection with only two or three shots early in life but not flu.

Why do you have to take the influenza shots annually ?

What’s so special about the flu ?

Two factors make the flu a tough target.

1. First, there are more than 100 subtypes of the influenza virus, and the ones in circulation change from season to season.
2. Second, the flu’s genetic code allows it to mutate more quickly than many other viruses.

How do the flu virus multiplies ?

The flu spreads by turning a host’s own cells into viral production factories. When the virus is swallowed by a host cell, it injects its genetic material right  into the host nucleus. There it takes over the host’s cellular machinery that normally copies the host’s own genes and start making copies of the flu genes and creating more and more copies of the virus. That’s one hell of a terrorist in action.
These freshly minted influenza daughter viruses start infecting additional cells. Most viruses follow this script.

The trick with the flu is that its genetic material isn’t DNA, but a similar yet different compound called RNA. RNA viruses can mutate ( change their Genes) much faster. When cells synthesize DNA, a built-in proofreader recognizes and corrects mistakes, but the RNA synthesis mechanism doesn’t have this fail-safe.If errors creep in, they stick around, creating new variants of the virus in a regular manner

In summary :

1. RNA viruses can mutate much faster.
2. Secondly the flu’s genetic code is particularly adept in mutating more quickly than other viruses.
3. Those antigens are different for every strain of influenza. If vaccination has prepared the immune system for one strain, a different one may still be able to sneak by.
4. To make things even more complicated, sometimes two different strains combine to create an entirely new hybrid virus.
All of this makes vaccinating for the flu like trying to hit a moving, transforming target. That’s why scientists are constantly collecting data about which strains are circulating and checking to see how much those strains have mutated from previous year’s version.

Why annual shots ?

Twice in a year, the World Health Organization pulls together experts to analyze all that data. The scientists determine which strains to include in that season’s vaccine. Every year WHO picks up four most probable strains to recommend a quadrivalent vaccine for that year.

In spite of the flu’s evasive maneuvers, in recent years, WHO’s predictions have been almost always correct.

Herd immunity

Vaccination also helps protect other people in the community who may not be medically eligible for the shot by reducing the overall number of circulating viruses in the atmosphere. This is called herd immunity.

Can we get the disease from the shot ?

No.
The flu shot can’t give you the flu. It contains an inactivated virus that isn’t capable of making you sick.You might feel tired and achy after getting it, but that’s not an infection.It’s your normal immune response to the vaccine.

we have also made an inhaled vaccine that contains a weakened live virus. But this can’t be given to those with impaired immune systems.