Active Immunity
artificial active
Not everyone has an immunity to Swine Flu.
Not everyone has an immunity to Swine Flu.
I caught the flu after being exposed to someone who was sick.
People receive flu shots to build immunity to several varieties of the flu virus.
No, probably not. There is genetic material from Asian Pig Influenza in the A-H1N1/09 "Swine Flu", but it also has components of Avian (bird) Flu, European Pig Influenza and Human Flu. The new strain is very different from prior strains of the H1N1 flu or any other Type A Influenza viruses, so there should be no antibodies effective for A-H1N1/09m
Yes, flu vaccines will work. It is basically dead or weakened flu viruses that are injected into your body. When your immune system finds the viruses, it makes antibodies to kill them, and this develops an immunity to that specific type of flu. If you are asking how long from the time you get the shot until your immunity is developed, then for healthy adults it is usually 2-3 weeks after the vaccination. Children under 10 need two vaccinations given a month apart because of their immature immune system functioning. Their full immunity will develop 2-4 weeks after the second vaccination.
No, since the particular type and subtype of H1N1/09 pandemic swine flu from 2009 was a brand new virus, it is likely no one had immunity. Some people may have had some resistance from having had prior flu viruses that were very close to the new one, and some people do have hereditary resistance to some infections, but the majority of people, even those who have had the flu many times over their lives, did not have immunity against the swine flu prior to the 2009 pandemic. Those who have now had the H1N1/09 virus or the vaccine specifically for it, should now have immune protection.
Unless you were tested when you were ill, there is really no way to know for sure which type of flu you may have had. If you were not tested at the time, to be sure you have immunity to the swine flu, it is advised that you get a vaccination. It will not hurt you if you already had the same flu, and it can prevent another illness if the flu you had was a different strain. For best protection from the flu during the 2009-2010 flu season, get both a swine flu vaccination and a seasonal flu vaccination.
Because there are many strains of flu virus, so unless you have immunity to them all you will catch flu again.
Because they have either respectively not yet developed sufficient immunity, or may have weakened immunity.
There are many different types of flu and the seasonal flu shot only prevents three of the most likely to be circulating flu viruses. So if you happened to get exposed to a type of flu that wasn't in the vaccination, then you could get sick from it.Another reason might be that you caught the flu before you got the flu shot and so there was not time for the shot to work before you got sick.Another reason might be that you got the shot and then were exposed to the flu before your immune system could give you immunity from the vaccination. It takes around two weeks after getting the vaccination for an adult to have full immunity from it. For children under 10, a series of two vaccinations are needed given approximately a month apart, then it takes another few weeks before the body has developed the full immunity, so exposure during any of those time frames before full immunity can cause illness in those children.