• Flu vaccine: the causative factors of the comon cold are the influenza (rhino & corona) virus. Through the “antigen shift” & “antigen drift” these viruses change their antigen regularly from year to year. As a result, vaccination can’t show their effectiveness in the cold virus prevention.
• In the cold/flu treatment, people most likely use OTC medications such as decongestants, cough suppressants and expectorants. These products may make the cold sufferer feel better, but do nothing to shorten the length of infection. These popular over-the-counter remedies may have side effects such as drowsiness and dry mouth and may not be appropriate for individuals who have other conditions such as irregular heartbeat. The best approach to using these products is to target only the symptoms that are a problem.
• Because colds are caused by viruses, antibiotics have no role in treatment because they treat only bacterial infections
• Within the cold/flu season people most likely use antihistamine. These products are of particular concern and may not be effective, because the histamine is still present in the person’s body, almost all histamine are already bind with the histaminic receptor & produce their pharmacological effects.
• The mast cell stabilizer sodium cromogylate or its derivatives can only be applicable in the prophylaxis purpose.
• Mutation in influenza viruses, decrease the susceptibility against the  the specific antiviral like TAMIFLU (oseltamivir phosphate), RELENZA (ZANAMIVIR). Moreover, they are more effective in the prophylaxis rather than treatment.

Now let’s come to the characteristics natures of the vitamin C, which will explain the justification of my opinion.

One known function of Vitamin C in the immune system is aiding in the killing power of neutrophils.  Neutrophils are cells involved in the "first line of defense" of the immune system.  Netrophils will engulf (eat) harmful bacteria and viruses in an effort to stop an infection.  Once the neutrophils have engulfed any of the above, they use powerful oxidation reactions to kill or inactivate these agents.

Studies have shown that Vitamin C increases the killing power of neutrophils; therefore, making the immune system stronger in a sense.  
 
Its sequestering properties, or ability to "chelate" (tie up) certain metal ions may also play an important role.  There are many metals that are important for many forms of life including humans, animals, bacteria, etc. Therefore, the body has mechanisms to keep a strong hold on these metals. At the same time, harmful bacteria which may cause infections also have mechanisms to take these metal ions from the body.

Establish of my opinion.

Presenting at the 60th Anniversary Meeting of the American Academy of Allergy, Asthma, and Immunology (AAAAI) on Tuesday, Ritter and colleagues reported that 12 healthy subjects who took one gram of vitamin C a day for two weeks showed a boosted immune system response during that time.
What's more, when they looked at responses in four of the patients, they found that in two of them, the response to vitamin C took place within five hours. According to Ritter, this might mean that taking a vitamin C tablet at the first sign of a cold could achieve an effect quickly enough to ward off that cold. "You may not have to take it every day," she says.
Ritter and colleagues drew blood from the subjects before and after they had taken one gram of vitamin C a day for two weeks. They isolated the immune system cells from the blood of the subjects and measured the levels of immunity boosting substances called cytokines.
Certain virus-fighting cytokines were increased after two weeks of taking the vitamin; however, when they measured the levels two weeks later, they found that the levels had returned to normal, suggesting that the effect is short-lived.
     
So, Protect yourself and your child by following the recommended diet habit.