Swine Flu Vaccine - Influenza A (H1N1)

Swine Flu H1N1 Vaccine Basics and History

Pregnant woman having blood test in doctor's office
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Do you need a swine flu vaccine? The good news is that if you get the regular seasonal flu shot, you are likely getting immunized for the swine flu as well. The swine flu - Influenza A (H1N1) caused a world-wide pandemic in 2009. At that time, it was a new virus, but it has since evolved into a human seasonal flu virus. It is called swine flu because when identified in 2009 it was similar to a strain found in pigs.

It still circulates in pigs as well as humans.

When H1N1 was first circulating in 2009,  there was no vaccine immediately available for it. The seasonal flu vaccine that year didn't cover this new virus and a new vaccine had to be developed, tested, and FDA-approved before being given to the public. There was a concern as younger people may not have developed any prior immunity to this strain.

The public health emergency for 2009 H1N1 expired June 23, 2010. The 2010-11 vaccine covered this virus as well as others likely to circulate. In 2014, the swine flu was one of the predominant strains of seasonal flu in the United States. It was covered in the influenza vaccine that year. The trivalent vaccine issued each year since included influenza A(H1N1) as well as an Influenza A (H3N2) vius and an influenza B virus.

Should You Get the Flu Vaccine?

The CDC recommends a yearly flu vaccine for everyone aged six months and older.

Get vaccinated as early in the flu season as possible, October through May. The vaccines are adjusted each year to match the strains that are predicted to be the most common in the upcoming season. There can be surprises, such as in 2009. In those cases, an additional vaccine may need to be developed and disseminated to cover the new strain.

Swine Flu Vaccine 2009

The challenge in 2009 was to produce and disseminate an H1N1 vaccine. It couldn't be combined with the vaccine already in production that year. As initial supplies would be limited, the CDC issued guidance on who should get it first.

CDC’s Advisory Committee on Immunization Practices (ACIP) recommended that the 2009 swine flu vaccine should first go to:

  • Pregnant women
  • Household contacts and caregivers for children younger than 6 months of age
  • Healthcare and emergency medical services personnel
  • All children and young adults from 6 months through 24 years of age, and
  • Persons aged 25 through 64 years who have health conditions associated with higher risk of medical complications from influenza

Next, as swine flu vaccine improved to the point that all priority groups have gotten vaccinated, everyone from the ages of 25 through 64 years could get vaccinated too. Lastly, people 65 or older, who have the least risk from the swine flu will be offered the swine flu vaccine.They had the least risk due to the natural immunity they were likely have due to previous swine flu epidemics in their lifetimes.

Kids who wee nine years old and under needed two doses of the 2009 H1N1 swine flu vaccine separated by at least four weeks to get full protection against the swine flu.

Older children, like adults, needed just one dose.

Finding Swine Flu Shots

Although five companies were making H1N1 swine flu shots, including Sanofi Pasteur, Novartis, GSK, Medimmune and CSL, doctors weren't able to directly order swine flu vaccine from them. Instead, the federal government is purchased all of the swine flu shots and then distributed them via a centralized distribution program. Pediatricians and other healthcare providers could order swine flu vaccine if they wanted to receive swine flu vaccine to give their patients.

Although the swine flu vaccine was free, pediatricians would likely charge a small vaccine administration fee to their patients.

Swine Flu Vaccine Trials

The National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, conducted swine flu clinical trials to make sure the new swine flu vaccines were safe and effective. They were conducted at eight university research hospitals and medical organizations across the United States, including Baylor College of Medicine in Houston, Children's Hospital Medical Center in Cincinnati, and Emory University in Atlanta.

The first clinical trials tested whether one or two doses are needed and will test both 15mcg and 30mcg doses of vaccine. Although the trials started in adults, they were also tested in children.

The safety of the 2009 H1N1 vaccine continues to be monitored by the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) through reporting of vaccine side effects to VAERS.

1976 Swine Flu Vaccine

Although it is true that we didn't have a swine flu vaccine when this pandemic began, there once was a swine flu vaccine that was made to target the swine flu H1N1 strain that was found at Fort Dix, New Jersey. Because of fears that this swine flu strain was similar to the flu strain that caused the 1918 Spanish Flu pandemic, a vaccination program immunized more than 40 million people in the United States between October 1976 to December 1976.

The immunization program was stopped early because the swine flu pandemic didn't occur, and the swine flu vaccine was thought to cause many side effects, including Guillain-Barre syndrome.

It is important to note that the 2009 H1N1 swine flu vaccine that was used in the United States was basically a flu vaccine and the FDA states that it was 'manufactured using the same approved processes used to produce the seasonal influenza vaccines.' It did not contain any new adjuvants, which are vaccine additives that can help them to work better. It was the possibility that the 2009 H1N1 swine flu vaccine was going to contain some new adjuvants which made people originally think this was a 'new' vaccine and created some of the controversy about it.

Swine Flu Vaccine Timeline - 2009-2010

  • June 4, 2009 - the CDC has provided a candidate vaccine virus to several laboratories and manufacturers so that they can produce pilot lots of swine flu vaccines that can be tested to make sure they are safe and effective.
  • June 12 - Novartis, a Swiss drug maker, which makes the Fluvirin flu vaccine for seasonal flu, has announced that they have produced their first batch of swine flu vaccine. This is still an experimental vaccine though, that needs to complete clinical trials to make sure it is safe and effective before it can be further produced for everyone to use.
  • June 26 - although 115 million doses of seasonal flu vaccine is usually used each year, it is estimated that up to 600 million doses of swine flu (H1N1) vaccine may be needed in the fall, since most people will need two doses. Only about 60 million doses will likely be ready by September though.
  • July 9 - the US government will spend about $7.5 billion if a swine flu vaccination program is thought to be necessary in the fall, in addition to the billion dollars already spent on bulk ingredients for the swine flu vaccines being developed.
  • July 13 - the WHO has endorsed new recommendations about swine flu vaccination, including that health-care workers should be vaccinated as a first priority and that countries should next follow a step-wise approach to vaccinate other groups as swine flu vaccine becomes available, including pregnant women; those aged above 6 months with one of several chronic medical conditions; healthy young adults of 15 to 49 years of age; healthy children; healthy adults of 50 to 64 years of age; and healthy adults of 65 years of age and above.
  • July 22 - the first human trials for a swine flu vaccine in the United States are expected to start soon.
  • August 18 - the Department of Health and Human Services reports that a delay in swine flu vaccine development will mean that only about 45 million doses of vaccine will be ready by October 15. Another 20 million doses will be then be ready each week, with about 195 million doses ready by the end of December.
  • August 18 - pediatric trials for a swine flu vaccine are set to begin following reports that there were no safety concerns in adult trials.
  • September 2 - pediatricians who are interested in providing the H1N1 swine flu vaccine to their patients should begin to preregister with their state/jurisdiction contact. They will be shipped in mid-October via a centralized distribution program from private suppliers. Doctors will not be able to order them directly from the vaccine manufacturers.
  • September 15 - the FDA has approved the 2009 H1N1 swine flu vaccine and it is on track for delivery in October. It will be available as an injection with and without the preservative thimerosal, and as a nasal spray.
  • September 18 - the CDC states that 3.4 million doses of the nasal spray form of the H1N1 swine flu vaccine will be available in the first week of October.
  • September 21 - young children who are nine years old or younger will likely need two doses of the 2009 H1N1 swine flu vaccine at least twenty-one days apart to get the best protection against the swine flu.
  • October 6 - the first doses of the 2009 H1N1 swine flu vaccine are arriving at doctor's offices and clinics, although they will be in a very limited supply at first.
  • October 16 - the CDC reports that almost 6 million doses of the 2009 H1N1 swine flu vaccine have been shipped to doctors and clinics, which is well behind schedule.
  • October 28 - about 23 million doses of the 2009 H1N1 swine flu vaccine has now been allocated and ready for doctors and clinics to order.
  • October 30 - the World Heath Organization's Strategic Advisory Group of Experts (SAGE) on Immunization reports that 'experts reviewed early results from the monitoring of people who have received pandemic vaccines and found no indication of unusual adverse reactions' and that reported side effects are 'well within the range of those seen with seasonal vaccines, which have an excellent safety profile.'
  • November 6 - almost 36 million doses of the 2009 H1N1 swine flu vaccine has now been allocated and ready for doctors and clinics to order.
  • December 11 - over 76 million doses of the 2009 H1N1 swine flu vaccine have now been shipped to doctors and clinics across the United States.
  • December 15 - About 800,000 doses of the 2009 H1N1 vaccine have been recalled in a non-safety related H1N1 recall because of problems with the potency of the vaccine.
  • December 22 - About 4.7 million doses of the FluMist nasal spray version of the 2009 H1N1 vaccine have been recalled in a non-safety related H1N1 recall because of problems with the potency of the vaccine.
  • January 10, 2010 - This week is National Influenza Vaccination Week, 'a national observance to highlight the importance of continuing influenza vaccination beyond the holiday season.'
  • February 18 - The WHO has recommended that the 2009 H1N1 swine flu virus be included in next year's seasonal flu shot.
  • March 30 - The CDC 'continues to encourage vaccination at this time for all persons 6 months of age and older' because of 'ongoing, persistent 2009 H1N1 activity in the United States.'
  • The public health emergency for 2009 H1N1 expired June 23, 2010. The 2010-11 vaccine covered this virus as well as others likely to circulate.


CDC. H1N1 Clinicians Questions and Answers. Recommendations for the 2009 H1N1 Vaccine. Accessed October 2009.

CDC. Use of Influenza A (H1N1) 2009 Monovalent Vaccine. Recommendations of the Advisory Committee on Immunization Practices (ACIP), 2009. Accessed September 2009.

PandemicFlu.gov. Draft Guidance on Allocating and Targeting Pandemic Influenza Vaccine. Accessed April 2009.

Plotkin: Vaccines, 5th ed.

Sencer, David J. Reflections on the 1976 Swine Flu Vaccination Program. Emerging Infectious Diseases. Vol. 12, No. 1, January 2006.

WHO. Pandemic (H1N1) 2009 briefing note 2. Accessed July 2009.

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