The U.S. Food and Drug Administration has approved four vaccines against the 2009 H1N1 influenza virus.
Based on preliminary data from adults participating in multiple clinical studies, the 2009 H1N1 vaccines induce a robust immune response in most healthy adults eight to 10 days after a single dose, as occurs with the seasonal influenza vaccine.
Clinical studies under way will provide additional information about the optimal dose in children. The recommendations for dosing will be updated if indicated by findings from those studies. The findings are expected in the near future.
As with the seasonal influenza vaccines, the 2009 H1N1 vaccines are being produced in formulations that contain thimerosal, a mercury-containing preservative, and in formulations that do not contain thimerosal.
People with severe or life-threatening allergies to chicken eggs, or to any other substance in the vaccine, should not be vaccinated.
In the ongoing clinical studies, the vaccines have been well tolerated. Potential side effects of the H1N1 vaccines are expected to be similar to those of seasonal flu vaccines.
For the injected vaccine, the most common side effect is soreness at the injection site. Other side effects may include mild fever, body aches, and fatigue for a few days after the inoculation. For the nasal spray vaccine, the most common side effects include runny nose or nasal congestion for all ages, sore throats in adults, and -- in children 2 to 6 years old -- fever.
What is Influenza A (H1N1) 2009 Monovalent Vaccine?
Influenza A (H1N1) 2009 Monovalent Vaccine is an inactivated influenza virus vaccine indicated for active immunization of persons ages 18 years of age and older against influenza disease caused by pandemic (H1N1) 2009 virus.
How will I receive Influenza A (H1N1) 2009 Monovalent Vaccine?
Based on currently available information, the vaccination regimen is as follows:
Adults 18 years of age and older:
- A single 0.5 mL intramuscular injection.
Influenza A (H1N1) 2009 Monovalent Vaccine is an inactivated vaccine that cannot cause influenza but rather stimulates the immune system to produce antibodies.
Dosage Forms and Strengths
Influenza A (H1N1) 2009 Monovalent Vaccine, a sterile suspension for intramuscular injection, is supplied in two presentations:
- 0.5 mL preservative-free, single-dose, pre-filled syringe.
- 5 mL multi-dose vial containing ten doses. Thimerosal, a mercury derivative, is added as a preservative; each 0.5 mL dose contains 24.5 micrograms (mcg) of mercury.
Important information
Influenza A (H1N1) 2009 Monovalent Vaccine should not be used in patients who have hypersensitivity to eggs or chicken protein, neomycin, or polymyxin, or life-threatening reaction to previous influenza vaccination.
If Guillain-Barr¨¦ Syndrome (GBS) has occurred within 6 weeks of previous influenza vaccination, the decision to give Influenza A (H1N1) 2009 Monovalent Vaccine should be based on careful consideration of the potential benefits and risks.
Immunocompromised persons may have a diminished immune response to Influenza A (H1N1) 2009 Monovalent Vaccine.
What other drugs will affect Influenza A (H1N1) 2009 Monovalent Vaccine?
Do not mix Influenza A (H1N1) 2009 Monovalent Vaccine with any other vaccine in the same syringe or vial.
Immunosuppressive therapies may diminish the immune response to Influenza A (H1N1) 2009 Monovalent Vaccine.
Before receiving Influenza A (H1N1) 2009 Monovalent Vaccine
Safety and effectiveness of Influenza A (H1N1) 2009 Monovalent Vaccine have not been established in pregnant women, nursing mothers or in persons less than 18 years of age.
Influenza A (H1N1) 2009 Monovalent Vaccine Side Effects
The most common (= 10%) local (injection-site) adverse reactions were tenderness, pain, redness, and swelling. The most common (= 10%) systemic adverse reactions were headache, malaise, and muscle aches.
Any severe or unusual adverse reactions should be reported to the healthcare provider.
To report SUSPECTED ADVERSE REACTIONS, contact VAERS at 1-800-822-7967 and www.vaers.hhs.gov.
