Additionally, febrile seizures and Reye syndrome can occur, most commonly in children. Influenza-associated encephalopathy can occur directly from central nervous system infection from the presence of the virus in blood and presents as suddent onset of fever with convulsions, followed by rapid progression to coma. An atypical form of encephalitis called encephalitis lethargica, characterized by headache, drowsiness, and coma, may rarely occur sometime after infection. In survivors of influenza-associated encephalopathy, neurological defects may occur. Primarily in children, in severe cases the immune system may rarely dramatically overproduce white blood cells that release cytokines, causing severe inflammation.People who are at least 65 years of age, due to a weakened immune system from aging or a chronic illness, are a high-risk group for developing complications, as are children less than one year of age and children who have not been previously exposed to influenza viruses multiple times. Pregnant women are at an elevated risk, which increases by trimester and lasts up to two weeks after childbirth. Obesity, in particular a body mass index greater than 35–40, is associated with greater amounts of viral replication, increased severity of secondary bacterial infection, and reduced vaccination efficacy. People who have underlying health conditions are also considered at-risk, including those who have congenital or chronic heart problems or lung (e.g. asthma), kidney, liver, blood, neurological, or metabolic (e.g. diabetes) disorders, as are people who are immunocompromised from chemotherapy, asplenia, prolonged steroid treatment, splenic dysfunction, or HIV infection. Current or past tobacco use also places a person at risk.
Pegcetacoplan, sold under the brand name Empaveli among others, is a medication used to treat paroxysmal nocturnal hemoglobinuria (PNH).The most common side effects include injection-site reactions, infections, diarrhea, abdominal pain, respiratory tract infection, viral infection, and fatigue.Paroxysmal nocturnal hemoglobinuria is characterized by red blood cell destruction, anemia (red blood cells unable to carry enough oxygen to tissues), blood clots, and impaired bone marrow function (not making enough blood cells).Pegcetacoplan is the first treatment for paroxysmal nocturnal hemoglobinuria that binds to and inhibits complement protein C3. Pegcetacoplan was approved for medical use in the United States in May 2021. Pegcetacoplan binds to complement protein C3 and its activation fragment C3b with high affinity, thereby regulating the cleavage of C3 and the generation of downstream effectors of complement activation. Medical uses
Pegcetacoplan is indicated to treat adults with paroxysmal nocturnal hemoglobinuria (PNH). Pegcetacoplan is only available for patients who are under the special REMS program. Two weeks before receiving pegcetacoplan, patients must receive vaccinations for pneumonia, meningitis, or influenza type B. Patients who have been vaccinated in the past may still need to get vaccinated two weeks before initiation of the medication. Pharmacology
Patients with PNH have greater and uninhibited complement activity, which may leads to intravascular (inside blood vessels) or extravascular (within the liver or spleen) hemolysis. Adverse effects
Meningococcal (a type of bacteria) infections can occur in people taking pegcetacoplan and can become life-threatening or fatal if not treated early. Pegcetacoplan may also predispose individuals to serious infections, especially infections caused by encapsulated bacteria.