The FDA approved mFlusiva to help prevent the flu in adults ages 50 and older. The flu is a viral infection that affects the lungs and breathing airways. It causes a fever, body aches, and fatigue. mFlusiva is the first messenger RNA, or mRNA, vaccine approved for seasonal flu.Â
mFlusiva works by teaching your body how to defend itself. It carries small pieces of genetic instructions called mRNA into your cells. Your cells use these instructions to make harmless proteins found on the flu virus. Your immune system spots these proteins and builds protective antibodies against them. These antibodies help fight off the real flu virus if you come into contact with it.Â
The FDA approval was based on a large main study of 40,805 adults ages 50 and older. In this study, half of the people got mFlusiva and half got a standard flu shot. mFlusiva was better at preventing flu illness than the standard flu shot. About 2% of people who received mFlusiva got the flu, compared to 2.8% of people who got the standard shot.Â
For adults 65 and older, approval was granted under an accelerated pathway based on immune response data. In a study of 2,991 adults in this age group, mFlusiva triggered a stronger antibody response than a high-dose flu shot. A future trial will confirm the clinical benefits in this group.Â
mFlusiva is given as a single shot into the muscle of your arm. Health care providers recommend getting a flu shot once every year to stay protected.Â
The most common side effect is pain where you get the shot. Other common side effects include tiredness, a headache, muscle pain, joint pain, chills, and underarm swelling or tenderness. Most side effects are mild to moderate and go away within two days. Though rare, severe allergic reactions can happen, so your health care provider may ask you to wait a short time after getting the shot.Â
Tell your health care provider if you have ever had a severe allergic reaction to a vaccine component. You should also mention if you have a history of fainting after shots or a condition called Guillain-Barré syndrome. If you are pregnant, breastfeeding, or have a weakened immune system, discuss your options with your health care provider.Â
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