Your first 90 days
Your child's first 90 days after Fayuvi for Sanfilippo syndrome type A
What happens before the first fill, the days that matter, the label's rules and who to call, from the label, the drugmaker's own program and one insurer's written rules.
Fayuvi is not a medicine you pick up at a pharmacy and give at home. It is one infusion, given once at a hospital trained in gene therapy, after a run of tests that decide whether your child can have it. The weeks that follow are about a daily steroid, regular blood tests and some extra care with diapers. This page lays out that stretch from the FDA label, Ultragenyx's UltraCare program and one insurer's written rules.
What has to happen before the first bottle ships
Fayuvi has no REMS and no pharmacy fill, so the wait is for a diagnosis, an antibody test, blood work, insurance approval and a treatment center. These are the 6 things in the way, in order.
A confirmed diagnosis of type A
Fayuvi is approved only for Sanfilippo syndrome type A, also called MPS IIIA.
- The Cigna policy on this page asks for proof from a genetic test of the SGSH gene or an enzyme test showing missing sulfamidase.
- The label's own words limit it to children whose neurodevelopmental function is still preserved.Cigna policy
The AAV9 antibody test
Fayuvi carries the new gene inside a shell made from a virus called AAV9.
- The label calls for a test for antibodies against AAV9 before treatment and does not recommend Fayuvi when the level is 1:100 or higher.
- The label says no FDA-authorized test exists yet, and Ultragenyx answers testing questions at 1-888-756-8657.FDA label
Blood tests and a health check
Before the infusion the label calls for liver tests (ALT, AST, GGT and bilirubin) and a look at your child's liver history.
- It also calls for a platelet count and 2 clotting tests, PT and aPTT.
- Treatment waits until any significant infection is under control, and the team checks for conditions that make steroids riskier.FDA label
A plan for vaccines
The label says vaccines should be avoided for 30 days before treatment and for as long as your child takes the steroid.
- Ask the care team and your pediatrician whether any shots on the regular schedule should move.FDA label
A Qualified Treatment Center
Ultragenyx makes Fayuvi available through a network of Qualified Treatment Centers, U.S. healthcare institutions with specialized gene therapy expertise and training.
- Ultragenyx said in September 2026 that fayuvi.com would list the network.
- Ask the care team early which center is nearest to your family.Ultragenyx press release
UltraCare and the insurance approval
After you enroll in UltraCare, a Guide checks your coverage, finds out whether prior authorization is needed and checks the status of any appeal.
- If your plan does not cover it, the Guide can search for other coverage.UltraCare
The days that matter
Counted from the infusion on day 1, with the steroid from the day before, weekly blood tests in month 1 and 3 months of diaper care. Type your first-dose date and the tiles become real dates you can add to your calendar.
The tiles below count days from a first dose. Enter the date of yours, or the date you expect, and each tile becomes a real date on your calendar.
The date stays on your device. It is not sent to Trial Friend or anyone else. The calendar file works with Apple, Google and Outlook calendars.Diagnosis papers and the AAV9 antibody test
The specialist gathers the genetic or enzyme test that confirms type A and orders the AAV9 antibody test.
- A level of 1:100 or higher means the label does not recommend Fayuvi.
UltraCare enrollment and insurance
An UltraCare Guide runs a full benefits investigation and finds out whether prior authorization is needed.
- The Guide also follows up if a denial is appealed.
Last vaccines for a while
The label says vaccines should be avoided from 30 days before treatment until the steroid course ends.
- Any shot your child needs should be planned around this window.
Baseline blood tests and weight
Liver tests, a platelet count and clotting tests set the baseline that later results are measured against.
- Your child is weighed, because the dose and the kit size depend on weight.
The steroid starts
Prednisone or prednisolone by mouth, 1mg/kg a day, starting the day before the infusion.
- The label asks you to call the care team at once if a dose is missed or vomited up.
The infusion
One slow infusion over about 1 hour, through a regular IV in a peripheral vein, not a central line or port.
- The team watches for reactions during and after, and a second IV line is recommended in case one is needed.
Week 1 blood tests
Liver tests and a platelet count are due this week.
- The label says platelet drops have generally happened within the first 2 weeks, and liver enzyme rises most often start within 14 days.
Week 2 blood tests
Liver tests and a platelet count are repeated this week.
- After this visit, liver tests move to every 2 weeks while platelets stay weekly through week 4.
Week 3 platelet count
This week brings a platelet count on its own, with no liver test.
- Watch for bruising or bleeding you cannot explain, which the label says needs medical attention.
Week 4, the last weekly platelet check
Liver tests and the fourth weekly platelet count are due.
- From here, platelets are checked monthly until 6 months after the infusion.
Liver tests, every 2 weeks
Liver tests continue every 2 weeks until 2 weeks after the steroid taper ends.
- If they rise, the steroid dose may go up or last longer.
The steroid taper decision
After 8 weeks, the label says the steroid is tapered if liver enzymes are at or below where they started.
- The taper then lasts at least 4 weeks, by the label.
- Liver tests continue every 2 weeks, and a monthly platelet count is due around now.
Earliest end of the steroid taper
An 8-week course plus a 4-week taper ends around here at the soonest.
- Liver tests run until 2 weeks after the last steroid dose, and vaccines can be discussed again once the steroid has stopped.
Diaper and hand washing care ends
The label asks families to seal used diapers in bags and wash hands after contact with body fluids or waste for 3 months after the infusion.
The label, revision by revision
The FDA lists which sections changed in each revision of a label. These are the revisions the current Fayuvi label records, dated by the FDA, with a plain note on what each one meant for a patient. Older references and handouts can lag these by months.
Label dated October 1, 2026, read on DailyMed. FDA label
- October 2026
The label was posted on DailyMed with an October 2026 revision date. The sections compared for this page match the September 2026 package insert, with no boxed warning and no contraindications.FDA label
- September 2026
In the approval letter, Ultragenyx committed to studies supporting an FDA-authorized AAV9 antibody test, with completion due December 31, 2028.FDA letter
- July 2025
The FDA's approval letter says a March 2026 resubmission answered its earlier action letter of July 7, 2025, which did not approve the first application.FDA letter
How the label says to take it
The parts of the prescribing information and the patient leaflet that come up in the first 3 months, in plain words.
- Given once, by weight
The label dose is 3.0 × 10¹³ vector genomes per kilogram, given one time.
- Fayuvi arrives as a kit of 5 to 105 vials matched to your child's weight.
- Children over 70kg (about 154 pounds) are dosed as if they weighed 70kg.FDA label
- How the infusion goes in
The label calls for a regular IV in a peripheral vein, a syringe pump and a filter, and says not to use a central line or port.
- If a reaction happens, the infusion is paused and may restart more slowly.FDA label
- The daily steroid
Prednisone or prednisolone starts the day before the infusion at 1mg/kg a day for 8 weeks, then tapers over at least 4 weeks.
- The care team may raise the dose or stretch the course if liver tests rise.FDA label
- A missed or vomited steroid dose is a phone call
The label asks families to contact the healthcare provider immediately if a steroid dose is missed or vomited up.
- Ask the care team which number to call after hours.FDA label
- Check every new medicine and supplement
The label asks families not to give any medicine, herbal product or supplement without first confirming with a healthcare professional that it is not harmful to the liver.FDA label
- Vaccines wait
Vaccines should be avoided for 30 days before treatment and while your child is on the steroid, according to the label.
- Ask the care team when the regular schedule can pick up again.FDA label
- Diapers and hand washing for 3 months
Fayuvi leaves the body for a while in urine, stool and saliva.
- The label asks families to seal used diapers in a bag before putting them in the regular trash and to wash hands after contact with body fluids or waste.FDA label
- Reporting a cancer
Because AAV vector DNA may join the body's own DNA, the label lists cancer as a possible risk.
- If your child ever develops one, the label asks you to tell your provider and Ultragenyx at 1-888-756-8657.FDA label
What the label says to act on
The symptoms the label singles out, and what it tells patients and prescribers to do about each. If any of these happen, the label's instruction is the one to follow, with your care team.
Yellow skin or yellow whites of the eyes
The label lists this as a sign of liver trouble and asks families to contact the healthcare provider immediately.
- Liver enzyme rises happened in 85% of children in the studies, most often within the first 14 days.FDA label
Bruising or bleeding you cannot explain
Fayuvi can lower platelets, generally within the first 2 weeks.
- The label says to seek medical attention for unexpected bruising or bleeding.FDA label
Seizures, passing less urine, or bruising and bleeding
These can be signs of thrombotic microangiopathy, which can lower platelets and red blood cells and harm the kidneys.
- It has been reported with other AAV gene therapies but not with Fayuvi in its studies.
- The label says to seek immediate medical attention for any of them.
- Ask the team how to tell a new seizure from your child's usual pattern.FDA label
Reactions during or after the infusion
Low blood pressure, fever, a pounding heart, nausea, vomiting, chills or headache can be infusion reactions.
- The label says to tell the medical staff right away.FDA label
Common side effects
In 27 children given the approved dose, vomiting occurred in 67%, behavior changes in 56%, diarrhea in 48% and fever in 41%.
- A rounder, fuller face (Cushingoid features) occurred in 30%, and reduced appetite in 22%.FDA label
Why the pharmacy or the insurer says no, and what fixes it
Most first-fill delays are one of these. Knowing which one tells you who to call.
- The AAV9 antibody level is 1:100 or higherThe label does not recommend Fayuvi at this level, and Cigna requires a baseline result below 1:100. This is a medical limit, not a paperwork problem, and the specialist can explain what it means for your child.Cigna policy
- The diagnosis is not documented as type ACigna asks for a genetic test showing SGSH variants or an enzyme test showing missing sulfamidase. The specialist's office sends the genetic or enzyme report to the plan.Cigna policy
- The prescriber is not the right kind of specialistCigna requires a neurologist, medical geneticist or metabolic disease specialist to prescribe Fayuvi. A referral to one of these specialists, or a consult note, fixes this.Cigna policy
- The weight on file is too oldCigna needs a body weight from the past 30 days, since the kit is built for that weight. The office weighs your child again and sends the new weight to Cigna.Cigna policy
- The approval ran out before the infusionCigna's approval covers one dose and stays open for 90 days. If scheduling slips past that window, the office asks Cigna for a new approval.Cigna policy
- Your child had another gene therapy beforeCigna does not cover Fayuvi after any earlier gene therapy, because Fayuvi was not studied in that group.Cigna policy
- Out-of-pocket costs you cannot payUltraCare's Copay Assistance program may cover out-of-pocket costs for the medicine and its administration for families with commercial insurance who meet Ultragenyx criteria. With government or commercial insurance, 501(c)(3) foundations may help with incidental medical costs related to the disease, and families apply to them directly.UltraCare
Cigna prior authorization policy, October 16, 2026
- The child has not had Fayuvi before, checked in claims or confirmed by the prescriber
- Sanfilippo syndrome type A confirmed by a genetic test of the SGSH gene or an enzyme test showing missing sulfamidase
- A baseline AAV9 antibody level below 1:100
- Prescribed by a neurologist, medical geneticist or metabolic disease specialist
- A body weight taken within the past 30 days
- The label dose of 3.0 × 10¹³ genome copies per kilogram, checked by a Medical Director against the weight
Approval length. One dose per lifetime, with the approval open for 90 days to give it.
This is Cigna's first policy for Fayuvi, effective October 16, 2026, and it cites the September 2026 label. It treats Fayuvi after any earlier gene therapy as not medically necessary. Its criteria do not spell out how to show preserved neurodevelopmental function, which is part of the label's approved use. It is here as an example of what a plan asks for, not as a rule. Cigna policy
Who to call, and what they can do
The drugmaker's program handles most of the first-fill problems above. Charity funds and foundation help are on the help paying page.
- An UltraCare Guide assigned after you enroll, who helps you understand your insurance coverage
- Specially trained Gene Therapy Guides, now part of UltraCare, who also help arrange treatment support and answer questions about the treatment process Ultragenyx press release
- A full benefits investigation, a check on prior authorization, the status of any appeal and a search for other coverage
- Copay Assistance for commercial insurance that may cover out-of-pocket costs for the medicine and its administration, for patients who meet Ultragenyx criteria
- Information on 501(c)(3) foundations that may help with incidental medical costs related to the disease, for government or commercial insurance
- Patient Assistance programs whose details UltraCare explains by phone
Details as the drugmaker publishes them. UltraCare
Five questions for the pharmacist or the support line
- Which Qualified Treatment Center is nearest to us, and how long is the wait for a date?
- Who runs the AAV9 antibody test, and when will we get the result?
- Which lab do the weekly blood tests go to, and can they be drawn closer to home?
- What do we do if our child vomits the steroid or refuses it?
- Which of our child's current medicines or supplements need a liver check?
- Does UltraCare or our plan help with travel and lodging for the infusion visit?
Questions people ask in the first weeks
Is Fayuvi given more than once?
No, Fayuvi is given one time only, as a single dose. The label describes a single infusion into a vein over about 1 hour. All children in the main study developed antibodies to AAV9 afterward, and Cigna approves it once per lifetime.
Which children can get Fayuvi?
The label covers children with Sanfilippo syndrome type A whose neurodevelopmental function is still preserved. It is not recommended when the AAV9 antibody level is 1:100 or higher. The specialist decides whether a given child fits the label and the plan's rules.
Why does my child need steroids with Fayuvi?
The label gives prednisone or prednisolone to every child because Fayuvi can raise liver enzymes. It starts the day before the infusion at 1mg/kg a day for 8 weeks, then tapers over at least 4 weeks.
How many blood tests are there after Fayuvi?
Platelet counts are weekly for 4 weeks, then monthly until 6 months after the infusion. Liver tests are weekly for 2 weeks, then every 2 weeks until 2 weeks after the steroid taper ends.
Can my child have vaccines around Fayuvi?
The label says vaccines should be avoided for 30 days before treatment and while your child is on the steroid. Ask the care team and your pediatrician how to adjust the regular schedule.
Is my child contagious after the infusion?
Traces of the gene therapy's DNA leave the body in urine, stool and saliva for a while, according to the label. For 3 months it asks families to seal used diapers in bags and wash hands after contact with body fluids or waste.
Where is Fayuvi given?
Ultragenyx makes Fayuvi available through a network of Qualified Treatment Centers, U.S. healthcare institutions trained to give gene therapy. An UltraCare Guide at 1-888-756-8657 can help with the steps to get there.
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Sources
- DailyMed - FAYUVI- rebisufligene etisparvovec-hopf kit (prescribing information, revised October 2026, SPL version 1), Ultragenyx, via DailyMed, October 1, 2026.
- Package Insert - FAYUVI, FDA, September 17, 2026.
- FAYUVI, FDA, Center for Biologics Evaluation and Research, October 15, 2026.
- September 17, 2026 Approval Letter - FAYUVI, FDA, September 17, 2026.
- September 17, 2026 Summary Basis for Regulatory Action - FAYUVI, FDA, September 17, 2026.
- Ultragenyx Announces Approval of FAYUVI™ Gene Therapy, the First-Ever FDA-Approved Treatment for Sanfilippo Syndrome Type A (MPS IIIA), Ultragenyx, September 17, 2026.
- Patient Services - UltraCare, Ultragenyx, November 9, 2026.
- Mucopolysaccharidosis – Gene Therapy – Fayuvi, Drug Coverage Policy IP0849, Cigna, October 16, 2026.
This page explains what the FDA label, the drugmaker's support program and an insurer policy say. It is not medical advice and does not tell anyone to start, stop or change a medicine. Dosing, test timing and restarts after a gap are decisions for the prescribing metabolic genetics specialist. Found an error? Use the report link in the footer and it will be checked against the source.