Get Your Flu Shot Now, Health Officials Urge
December 5, 2014
Officials at the United States Centers for Disease Control and Prevention (CDC) are finding that vaccines administered this year to protect people from influenza (the flu) are not as effective as they had hoped. But, they stressed, people should not use this as an excuse to skip this year’s flu shot. In addition to feeling miserable, people with the flu may develop flu-related complications that may lead to hospitalization and death, health officials said. Children and the elderly are especially at risk.
Global flu outbreaks occur each year, usually in winter months. Each outbreak is caused by viruses slightly different from those associated with earlier outbreaks. The differences are caused by mutations that occur in the viruses. A mutation is a change in the hereditary material of an organism. Mutations in a flu virus may cause an unexpected flu strain to become more common in a given year. That seems to be the case in 2014. This strain was associated with severe outbreaks, including higher-than-normal numbers of hospitalizations and deaths, during the 2003-2004, 2007-2008, and 2012-2013 flu seasons.
Influenza viruses may cause flu when they are inhaled. The viruses shown here are greatly magnified and artificially colored. (© Linda Stannard, UCT/SPL from Photo Researchers)
Vaccine manufacturers must produce flu vaccine months before any outbreak in order to ensure sufficient vaccine supplies when flu season hits. But the vaccine must closely match the strains (types) in each year’s outbreak. The decision on what strains should be used in a year’s vaccine is based on the common strains found worldwide by global health agencies in the past year. However, CDC scientists found that fewer than half of the flu virus samples obtained from patients from October and November 2014 matched any of the strains used to make this year’s vaccines. Scientists often name the different flu strains after the place where the strain was first identified. This year’s flu vaccines were made to match several flu strains, including one called A/Texas/50/2012. But in samples from flu patients taken in October and November, only 48 percent matched this flu strain. Most of the other virus samples were from a strain called A/Switzerland/9715293. This strain was not used to make flu vaccine in 2014. As a result, the flu vaccine currently used is not as effective at protecting people from this strain.
Nevertheless, medical experts note that even if a vaccine does not exactly match the most common strains of flu circulating, the vaccine still provides significant protection. People who have had a flu shot may still get sick this year. However, they will typically experience a less severe illness than they would have without the shot. CDC officials stressed that over the years, hundreds of millions of Americans have safely received flu vaccines. The most common side effects are soreness, redness, tenderness or swelling where the flu shot was given and nasal congestion after the flu vaccine nasal spray.
Additional World Book articles:
- Epidemic
- Spanish flu
- Influenza: A New Threat from an Old Foe (a Special Report)
- Handwashing: The First Line of Defense Against Disease (a Special Report)
Information about flu and flu vaccines can be found on the Influenza page of the CDC website.
