The Flu Vaccine

My aunt doesn't believe in the flu vaccine and doesn't really want to vaccinated her two kids(ages 11 and 7).  So, this year, she did a survey of her Facebook friends and asked them if they got the vaccine and if they got the flu.

Her results:
Out 306 of my friends who reported, 55 have been ill with flu-like symptoms this flu season (17.974%).
-151 were vax'd and 32 reported illness (21.119%)
-154 were unvax'd and 23 reported illness (14.935%)
-The vax'd group had illness at a rate 6.184% higher than the unvax'd group.
-Of the four respondants who are over 65, 3 of 4 were vax'd and 0 of 4 became ill.

She uses this to reinforce her anti-vaccine attitude.

Here's the problems with the study.  First, she only used risk difference for her results (that's the percent thing she has), which is just not that good of a measure.  A better measure is a ratio, which still shows the same results, but has the meaning that she attributed to the percentage.
Second, her study does not have any cases of confirmed illnesses.  So, for all we know, these people were all hit with a heavy-duty cold.
Third, the flu doesn't always show symptoms in the infected people.
Fourth, many people call stomach bugs the stomach flu(which is stupid, because there is no such thing and then people get it confused with influenza), which means that some of these that reported illness may be reporting food poisoning as flu.
Fifth, she collected no information about why those who got vaccinated chose to do so.  Are they at greater risk for the flu?  I know that my aunt has many friends who homeschool(as she does herself).  It goes without saying that if you aren't around sick people, you have a much lower chance of getting sick.  When did the people get ill?  If it was within two weeks of the vaccine, the vaccine didn't fail to protect them, they didn't have protection yet.
Sixth, there is no evidence that those who got the vaccine and those who didn't were roughly equal in demographics.  There is no evidence that these are control groups and treatment groups, but there does appear to be evidence that these people are not the same, as they did not get the flu at the same rate(which is what would be expected in the flu vaccine does not work).

There.  "Study" debunked.