Thanks to vaccines, many diseases that used to afflict mankind have been eliminated or significantly reduced. Unfortunately, there are many myths surrounding vaccines that discourage people from getting vaccinated.

Myth or fact: “Vaccines themselves cause disease.”

Fact: Vaccines are safe and effective so long as they are used correctly.

Vaccines are drugs. Like any other drug, they have benefits and potential side effects. So the real question is: are the benefits of getting a vaccine worth the risks? The answer is: it depends. The flu shot is routinely given to pregnant women because it is a safe and effective way to protect both mother and baby from influenza. Then there are other vaccines that should be avoided during pregnancy or in children younger than a certain age. For example, Pneumovax, a vaccine used to prevent pneumonia, should not be used in children younger than two years old simply because it will not be as effective in this age group. Varivax, the vaccine used to prevent chicken pox, is safe and effective in children as young as one year old, but should be avoided in pregnant women.

The truth is that, as with other drugs, certain vaccines should be avoided in certain people. The following websites provide a list of who should and should not be vaccinated:

www.vaccines.gov/basics/safety/should/index.html

www.cdc.gov/vaccines/vpd-vac/should-not-vacc.htm

Myth or fact: “Diseases began to disappear long before vaccines were available.”

Fact: True reduction in infectious diseases did not occur until after vaccines became available. This is easily proven by comparing the actual number of cases of infectious diseases before and after vaccines became available. Here is one example: in the early 1980s the Haemophilus influenzae bacteria (Hib) caused more than 20,000 cases each year of pneumonia, meningitis and other serious diseases. After the Hib vaccine became available the number of cases decreased from 20,000 to 17 by 2010.

Myth or fact: “You should avoid getting the flu shot when you are sick.”

Fact: It depends on how sick you are. Vaccines are usually postponed if you have a moderate or severe illness, but if you have a mild illness, such as a head cold, you may still be able to receive the flu shot.

Myth or fact: “I don’t need the flu shot this year because I already got the flu shot last year.”

Fact: Unfortunately, last year’s flu shot only protects you from last year’s virus. Every year the virus mutates and changes enough that the body’s immune system fails to recognize it. That is why each year scientists look at how the virus has mutated and then they update the flu vaccine so that it protects you from the new form of the virus. In essence, you need the flu shot each year because it will “teach” your immune system to recognize the new form of this ever changing virus.

Myth or Fact: “Every time I get the flu shot, I end up getting the flu.”

Fact: It is impossible for the flu shot to give you the flu because it contains an inactive (dead) version of the virus. Also, bear in mind that the flu shot takes two weeks to take effect. So suppose you got the flu shot today and two days later someone at work sneezes, unknowingly exposing you to the flu virus. When you come down with flu symptoms it would be easy to blame it on the flu shot (when actually you got it from the person who sneezed), or to mistakenly conclude that the flu shot failed to protect you, when actually it did not yet take effect because it takes two weeks to work and you only got the shot a few days earlier.

[Reymond Barreto is a registered pharmacist and holds a Doctor of Pharmacy degree from the University of Florida. He has been a practicing pharmacist for 20 years and currently resides in Sullivan County, NY. He can be reached at reypharmd@yahoo.com. In a future column he will continue his look at Vaccines: Myths and Facts.]