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AsthmaDecember 2024Summary reviewed November 2026

Twice-yearly injection cuts severe asthma attacks by more than half

People with severe asthma and high eosinophil counts who received this injection twice a year had far fewer asthma attacks than those on placebo. The treatment reduced attack rates from about 1 per year to roughly half that, and was well-tolerated.

What the trial was testing

The SWIFT-1 and SWIFT-2 enrolled 395 patients with asthma. The study was sponsored by GlaxoSmithKline and tracked outcomes across the full group of patients who matched the trial's eligibility profile.

It was a large trial designed to confirm whether the treatment works well enough for wider use. Trials at this stage are designed to produce evidence regulators and physicians can act on — not just observations to follow up later.

What the results showed

Asthma attacks dropped by 58% compared to placebo in one trial, 48% in the other.

The New England journal of medicine · 2024 · NCT04719832

These findings — that annualized exacerbation rates fell 58% and 48% vs. placebo across two trials — were published in the The New England journal of medicine and represent the headline result of the study.

Researchers tracked outcomes across 395 patients enrolled in the trial. The result was consistent enough across the group that the team felt confident reporting it.

What this means for patients

For patients with asthma, this result changes the calculus on what to ask their care team about. Whether it changes day-to-day care depends on factors like disease subtype, prior treatments, and where the patient is in their care journey.

What you can do now

If you have severe asthma that's not controlled even on high-dose inhalers, this treatment could mean significantly fewer attacks and emergency visits. The injection is given just twice a year, which is much simpler than daily pills or frequent dosing. This is an FDA-approved option — talk to your doctor about whether you're a good candidate.

Eligibility for the treatments mentioned above depends on specific test results and clinical history. Bring this summary, the trial name, and your most recent labs or pathology report to your next visit.