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There are thousands of different viruses and even the same virus will have mutated
over a year so it becomes a "cousin of a cousin's great great grandchild".
A vaccine is a small dose of the virus. Not enough to make you ill, but enough that
your body recognizes THAT PARTICULAR invader and learns to fight it.
Wiki User
∙ 14y ago
Wiki User
∙ 14y agoBecause the strains of viruses that cause the seasonal flu mutate very rapidly and by the time the virus has spread during the flu season and then moved on, it usually will have started to mutate and will no longer be prevented by the prior year's vaccines.
Wiki User
∙ 11y agoThere are different kinds of influenza. So a vaccine against one, usually won't be effective against another. Also, the flu virus mutates easily and rapidly. When it mutates, the old vaccine is may no longer be effective, depending on how different the mutation is to the original strain. It is also under study to determine if there is a gradual loss of immunity from flu over long time periods as some believe occurs in some people with use of some vaccines and with some types of flu.
Wiki User
∙ 7y agoThe flu virus changes over time. By next year, it isn't exactly the same as it is this year.
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Should you get a Swine Flu vaccination if you got a seasonal flu shot?
Last flu season, 2009-2010, you needed two shots. But this year the seasonal flu shot also protects against swine flu, so, in the US, you only need one flu shot for the 2010-2011 flu season.
What are seasonal plants?
seasonal plants are grown in seasons only.
Does Justin Bieber have the seasonal flu?
he was really sick at the end of last year.
What is seasonal goods?
Seasonal goods refer to the merchandise that is only popular during certain times of the year. The period may be Easter or Christmas
What are some seasonal constellations?
Most constellations are seasonal, meaning they appear in the sky during reasonable evening hours only at certain times of the year. For example, Orion is a popular winter constellation. Only circumpolar constellations are not seasonal.
Why is sugar industry seasonal?
sugar industry is considered as a seasonal industry because sugarcane operates only 20 to 32 weeks in a year.......
What is the definition of seasonal expense?
Seasonal expenses are things you only have to buy or pay for at certain times, such as certain seasons of the year, or certain months, etc.
Is a pediatrician year round or seasonal?
it all depends on the doctors if they want to work year round or seasonal.
How often do they get shots?
they should get shots once a year.
Is the chef occupation full-time year round or seasonal?
It would depend on where you're a Chef. If it's a restaurant that's open year-round, then you have a year-round job. If you cook at a ski resort that's only open for business in the winter, then you have a seasonal job.
What is Seasonal variation?
Variation in the values of a variable dependent upon the time of the year is seasonal variation. A variable having seasonal variation exhibits a pattern that repeats after exactly one year.
How long does a rabies shot last?
it depends on the type of animal,for example u have to give a cat rabies shots every 3 years, dogs rabies shots every 5-7 years or lower.You have to take prophylactic vaccine for rabies on day 0, 7, 28 and 90 or on day 0, 28 and then on day 90. Booster doses are to be taken yearly.
