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Flu Vaccine (cont.)

Thimerosal and Mercury in Seasonal and Pandemic Vaccines

Thimerosal is a preservative that contains mercury and is used in multidose vials of conventional and pandemic flu vaccines to prevent contamination when the vial is repeatedly used to extract the vaccine. Although thimerosal is being phased out as a vaccine preservative, it is still used in flu vaccines in low levels. There is no data that indicate thimerosal in these vaccines has caused autism or other problems in individuals. Consequently, the FDA has indicated the following:

  • There is no convincing evidence of harm caused by the small doses of thimerosal preservative in influenza vaccines, except for minor effects like swelling and redness at the injection site.
  • A study of influenza vaccination examining over 2,000 pregnant women demonstrated no adverse fetal effects associated with influenza vaccine.

However, single-dose vials and the nasal-mist formulations of both the seasonal and pandemic vaccines contain no thimerosal. These vaccine options are available to individuals who still want thimerosal-free vaccine. In addition, the new intradermal vaccine has no thimerosal. For thimerosal levels in flu vaccines, the reader should see the CDC table in the reference
under "mercury content."

What Is the Value for Individuals Getting Seasonal and Pandemic Vaccine?

The best chance for protection against seasonal (conventional) and pandemic flu is vaccination. The value for getting vaccinated is very high for many individuals and even for the world's population. For individuals, seasonal flu often causes about 36,000 deaths in the U.S., with about 200,000 people hospitalized every year. About 5%-20% of the U.S. population gets the seasonal flu each year and misses school, work, and vacation time, while productivity nationwide can decline. Seasonal flu takes the lives of our population 65 years of age and older; about 90%-95% of seasonal flu deaths occur in this age group. Without yearly seasonal flu vaccine, the illness and death rates would likely be much higher.

Pandemic flu in some instances can be far worse on world populations than seasonal flu. For example, the Spanish flu or 1918 flu pandemic killed about 40 million to 100 million people from 1918-1920. Commerce, economic systems, and travel were shut down in many areas of the world for months at a time during those years. In the recent H1N1 pandemic that began in Mexico in April 2009, the disease caused deaths "out of the usual flu season" and caused a shutdown in travel to Mexico that brought the country economic hardship. For many individuals, pandemic H1N1 flu was just a nuisance that makes people feel feverish and tired with sneezing and coughing that lasts for about a week; they recovered without any problems. For others, the pandemic H1N1 flu was disastrous and deadly. The H1N1 virus has behaved quite differently from the seasonal flu; it began in April 2009 (near the end of the seasonal flu season) and spread worldwide by September. H1N1 flu affected a different population than the seasonal flu; it caused the hospitalization and deaths of a markedly younger population (pediatric population, pregnant individuals, and young adults). Worldwide, H1N1 vaccine became available in limited amounts in late September and early October 2009. The H1N1 vaccine was initially given to those people at highest risk for complications (pediatric/children, pregnant women, caregivers). Researchers suggest the H1N1 vaccine was effective in reducing the effects of this flu virus, even though it was not as deadly as first estimated.

Vaccination against seasonal flu and the infrequent pandemic flu (1918 [no vaccine], 1957, 1968, and 2009) has been improved since it was first tried in the 1940s. Vaccination provides the best chance (about 70%-90%) to prevent the symptoms and complications (including pneumonia) of influenza infection from developing; the value of vaccinations is in the numbers of people who live and do not get sick from the disease because they were successfully vaccinated.

In the future, vaccines may be made differently; however, the vaccine hastily made in 2009 to protect people from H1N1 was deemed successful and can serve as a vaccine synthesis method until newer and faster vaccine synthesis methods are widely accepted.

Medically Reviewed by a Doctor on 10/25/2017

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