Routine Tylenol Use with Vaccine Administration in Infants May Decrease Vaccines' Effectiveness

Vaccines work in part by triggering a healthy immune response in the human body. Such an immune response alerts the body's immune system to the presence of foreign material, the vaccine, so that if a person comes into contacted with the living natural type of the bacteria or virus, such as during a flu pandemic, their immune system will be ready to swing into action and eradicate it from the body.

However, if a vaccine doesn't trigger a good immune response in a given person, it is sort of like the body ignoring the vaccine, and the person might no be effectively vaccinated. This is why vaccine manufacturers often add "adjuvants" to vaccines which help the vaccine illicit a stronger immune response from the body, and thus for the vaccine to be more effective.

Now a recent study in the medical journal Lancet, long recognized for publishing ground breaking work, is reporting that Tylenol, if given after a vaccination in children to reduce vaccine caused fever, can actually decrease the immune response to the vaccine, and possibly the effectiveness of the vaccine. The vaccines against Hib, pneumococcus, and tetanus showed reduced immune response after a dose of Tylenol was given after vaccination in infants to prevent fever.

A good immune response, i.e. production of a sufficient number of effective antibodies against the Hib bacteria, is important for children to have effective protection against this bacteria which prior to vaccination had resulted in a large number of cases of meningitis in children.

The clinical implications of the study are far from clear, however, the researchers recommended against the routine administration of Tylenol at the time of vaccination. This appears to be a sensible precaution if a child has not developed a fever. If your child has developed a fever after vaccination, especially if it is a high grade fever meaning above 100.4, you should contact your child's doctor for further instructions.

But why does Tylenol cause this problem? Young children after often advised to take Tylenol instead of aspirin as aspirin use in children with fever has been associate with Reyes syndrome. Tylenol, however, is not a completely safe medication either, indeed, Tylenol causes three times more episodes of liver failure than all other medications combined, and is the most common cause of acute liver failure in America. However, this is partly due to the large amount of Tyleonol consumed each year. When used as directed Tylenol is a safe medication for use in children and adults.

Possibly Tylenol's weak anti-inflammatory properties inhibit some branch of the immune system involved with response to foreign material, such as vaccines, or alternatively fever, even low grade fever, itself could be important for developing a healthy immune response to a vaccine in some individuals.

Likely, more research will be completed on the use of Tylenol after vaccination, which could perhaps lead to more effective vaccines in the future.

Sources:

Post-Vaccine Tylenol May Harm Immune Reponse
http://abcnews.go.com/Health/SwineFlu/tylenol-shots-hurt-vaccines-effectiveness/story?id=8840239

Tylenol
http://en.wikipedia.org/wiki/Tylenol