Your Baby’s RSV Shot: The 2026–27 Dates Are Now Set — and There Are Two Antibody Options to Choose Between

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Last updated: August 2026. This article is for general information and is not a substitute for personalised advice from your doctor, health visitor, or paediatrician. See our Editorial Policy.

Quick answer: For the 2026–27 season, CDC’s administration windows are September 1, 2026 – January 31, 2027 for the maternal RSV vaccine (Pfizer’s Abrysvo, given at 32–36 weeks of pregnancy), and October 1, 2026 – March 31, 2027 for the infant antibody shots (Beyfortus/nirsevimab or Enflonsia/clesrovimab). Your baby needs one route or the other, not both — if you got Abrysvo at least 14 days before delivery, your baby is generally covered for their first ~6 months and doesn’t need the antibody. If you didn’t, your baby should get an antibody dose: within a week of birth if born October–March, or in October/November if they were born April–September. There are now two antibody products and CDC states no preference between them, so either is fine — pick whichever your practice stocks. Book now: state immunization programmes are already staging supply — North Carolina’s opened ordering for all three products on August 3, 2026 — and October appointments fill up alongside flu and COVID shots.

Why this is worth doing in August, not October

This is the boring logistics story that quietly decides whether your newborn spends a February night in a hospital or in their own cot.

North Carolina’s state immunization programme opened ordering for all three RSV products on August 3, 2026, and in the July 23 provider memo that published CDC’s 2026–27 windows, it explicitly asked practices to order early “to avoid distribution bottlenecks when COVID-19 and influenza vaccines launch for respiratory season.” Other states are staging supply on similar timelines — check your own state’s schedule if you want the local date. Translation for parents: the supply is being lined up right now, and the appointment calendar for October is about to get crowded.

There’s a second reason August matters, and it’s the one most parents miss. If you are pregnant and due between roughly October and February, the maternal vaccine is only given in a narrow four-week gestational window (32–36 weeks) that also has to land inside the September–January administration season. Miss it and the decision defaults to your baby getting a shot instead. If you’re around 28–30 weeks right now, this is the conversation to have at your next appointment, not your last one.

The 2026–27 calendar, in plain dates

  • Abrysvo (maternal RSV vaccine) — for pregnant women at 32–36 weeks — September 1, 2026 to January 31, 2027
  • Beyfortus (nirsevimab) — for babies under 8 months entering their first RSV season, plus some high-risk 8–19 month olds — October 1, 2026 to March 31, 2027
  • Enflonsia (clesrovimab) — for babies under 8 months entering their first RSV season — October 1, 2026 to March 31, 2027

These are the windows for most of the continental US. CDC notes that timing can differ where RSV circulates on a different schedule — southern Florida, Hawaii, Puerto Rico, Guam, the US Virgin Islands, the US-Affiliated Pacific Islands, and Alaska, where RSV season is often longer and less predictable. Public health authorities in those areas may start earlier or run later, and your paediatrician can also use clinical judgement to give a dose outside the window.

Option A: the shot you get, so your baby doesn’t need one

Pfizer’s Abrysvo, given at 32–36 weeks of pregnancy, works by giving you antibodies that cross the placenta. It takes about two weeks after vaccination for that protection to build and transfer, which is why the 14-day rule matters so much.

  • Protection lasts your baby’s first roughly 6 months — the window when they’re at highest risk.
  • If your baby is born less than 14 days after you’re vaccinated, they should still get an antibody shot; there wasn’t time for the transfer.
  • If you had Abrysvo in a previous pregnancy, CDC does not currently recommend a repeat dose — this baby should get the antibody after birth instead.
  • CDC lists common side effects as headache, nausea, and injection-site pain, and notes that a possible link to hypertensive disorders of pregnancy, including pre-eclampsia, is under further study. That’s a real thing to raise with your obstetrician rather than something to discover in a comment section.

Option B: the shot your baby gets — and why there are suddenly two

Until recently there was one long-acting antibody for infants. Now there are two, and this is the part generating confused questions in parenting groups.

Beyfortus (nirsevimab). Dosed by weight: 50 mg for babies under 5 kg (11 lb), 100 mg for babies 5 kg and over. It’s also the only option for the small group of high-risk 8–19 month olds entering a second RSV season — children with chronic lung disease of prematurity who needed medical support (steroids, diuretics, or supplemental oxygen) in the preceding six months, children with severe immunocompromise, children with cystic fibrosis who have severe lung disease or poor growth, and American Indian or Alaska Native children.

Enflonsia (clesrovimab). A single 105 mg dose for every eligible baby regardless of weight, which is why practices sometimes find it simpler to stock. It’s approved only for babies under 8 months in their first season — not for second-season use.

Both are monoclonal antibodies, not vaccines. They don’t train the immune system; they are the antibodies, which is why protection is immediate rather than taking two weeks to build. Both provide protection lasting at least 5 months — roughly one full RSV season.

The adult RSV vaccines you may have seen advertised — GSK’s Arexvy, Moderna’s mResvia, and Abrysvo given to adults — are not approved for infants or young children. If someone tells you your baby is getting “the RSV vaccine,” they almost certainly mean the antibody shot.

“Which one should I ask for?”

CDC’s position is that either infant antibody is recommended and there is no preferential recommendation between them. Practically, that means: take the one your paediatrician has in the fridge. Chasing a specific brand across town in November is a worse outcome than getting a dose on time.

If you want the numbers behind that, they come from different trial designs and aren’t a head-to-head comparison, so read them as “both work well” rather than “one wins”:

  • Nirsevimab, pooled Phase II/III trials: 79.0% efficacy against medically attended RSV lower respiratory tract infection, 80.6% against RSV-associated hospitalisation, through 150 days. Early real-world data put it at at least 70% effective at preventing RSV hospitalisation.
  • Clesrovimab, clinical trials: 60.4% against medically attended RSV LRTI (95% CI 44.1–71.9%), 90.9% against RSV-associated LRTI hospitalisation (95% CI 76.2–96.5%), through 150 days.

The clesrovimab hospitalisation figure looks higher and the medically-attended figure looks lower, but the confidence intervals are wide and the trials measured slightly different populations and endpoints. CDC treating them as equivalent options is the honest reading.

Both can be given at the same visit as routine childhood vaccines, with no waiting interval needed before or after live vaccines like MMR or varicella. So this doesn’t have to be an extra trip.

Does it actually work outside a clinical trial?

This is the fair question, and the 2024–25 season was the first full one with both prevention routes widely available. CDC reported that real-world effectiveness studies estimate nirsevimab and maternal vaccination together protect against roughly 70–80% of RSV-associated hospitalisations in infants, and that two national surveillance networks measured RSV hospitalisation rates among babies aged 0–7 months as 43% and 28% lower than pre-pandemic seasons — two different networks, two different numbers, same direction.

For scale: before RSV immunisations existed, an estimated 58,000–80,000 children under 5 were hospitalised with RSV in the US each year, making it the leading cause of infant hospitalisation. CDC states that two to three out of every 100 infants under 3 months are hospitalised with RSV annually. (Merck’s own materials cite the same 2–3 per 100 figure for infants under 6 months, so the sources differ on the exact age band — either way, it’s a meaningful share of very young babies.)

What RSV actually looks like in a baby — the part worth memorising

RSV often doesn’t announce itself. It can look like a routine cold for a few days and then get worse, and most babies won’t run a fever.

Early signs: runny nose, eating or drinking less, a cough that may progress to wheezing or difficulty breathing.

In babies under 6 months, the signs are quieter and easier to miss:

  • Irritability
  • Decreased activity
  • Eating or drinking less
  • Apnea — pauses in breathing lasting more than 10 seconds

Seek medical care if your child is having difficulty breathing, isn’t drinking enough fluids, or is getting worse rather than better. Apnea in a young infant is a call-now sign, not a monitor-overnight one.

And the statistic that reframes the whole thing: most children will get RSV by the time they’re 2. The immunisation isn’t about avoiding the virus — it’s about not being hospitalised by it the first time round.

What it costs

Nirsevimab is covered by the Vaccines for Children (VFC) programme, which provides it at no cost to children who are Medicaid-eligible, uninsured, underinsured, or American Indian/Alaska Native. ACIP also voted to include Enflonsia in the VFC programme.

Most private insurance plans cover nirsevimab, and most cover the maternal vaccine, though your out-of-pocket cost depends on your plan — worth one phone call to your insurer now rather than a surprise bill in November. Under Medicaid and CHIP, ACIP-recommended vaccines are generally covered at no cost. If you’re budgeting for a first year, this sits alongside the other line items we broke down in the real cost of raising a baby in 2026.

Your five-minute action list this week

  • If you’re pregnant: work out what gestation you’ll be on September 1. If you’ll hit 32–36 weeks between September and January, ask about Abrysvo at your next appointment.
  • If your baby was born April–September 2026: they’re outside the birth-dose window, so ask your paediatrician to book an antibody dose for October or November.
  • If you’re due October–March: ask now whether your hospital gives the antibody during the birth stay. Ideally it happens before you go home.
  • Call your insurer and ask specifically whether nirsevimab/clesrovimab and the maternal RSV vaccine are covered, and at what cost.
  • Ask which product your practice is stocking — Beyfortus, Enflonsia, or both. It saves a confusing conversation in the room.

What actually helps at home during RSV season

None of this replaces the immunisation, but if a cold does land, these are the things that reduce misery for a congested baby:

  • A cool-mist humidifier for the nursery — dry winter air makes congestion worse.
  • A nasal aspirator and saline drops — the only genuinely effective way to clear a young baby’s nose before a feed, since they can’t blow it.
  • A reliable digital thermometer (rectal for under-3-months, per standard paediatric guidance) — RSV often doesn’t cause fever, but you want an accurate number when it matters.
  • Nothing extra in the cot. No pillows, wedges, or inclined sleepers to “help them breathe” — inclined sleepers (any sleep surface angled more than 10 degrees) are banned outright in the US under the Safe Sleep for Babies Act, and a congested baby is not an exception.

Our New Parent Starter Bundle already covers newborn essentials and hospital-bag planning; a one-page “RSV season timeline” showing when to book each shot by due-date month is a natural addition for anyone picking it up before autumn.

The bottom line

The 2026–27 RSV calendar is now fixed: Abrysvo September 1 to January 31, at 32–36 weeks of pregnancy; Beyfortus or Enflonsia October 1 to March 31 for babies. Your baby needs one route, not both. There are two infant antibody options now and CDC doesn’t prefer one over the other, so take whichever your practice stocks rather than shopping around. The mistake that costs families isn’t picking the wrong product — it’s arriving in December still meaning to call. Supply is already being staged for the autumn; the appointment book is the bottleneck, and it’s open today.

Sources

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