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Evaluation of NHS newborn screening for SCID extended to March 2024

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The UK National Screening Committee (UK NSC) last reviewed the evidence for newborn screening for severe combined immunodeficiency (SCID) in 2017 and the evidence looked promising, but more research was needed. The committee therefore recommended there should be a practical ‘in-service’ evaluation of screening for SCID in English NHS services to answer some important questions.

Following ministerial approval of this recommendation, the Department of Health and Social Care (DHSC) and NHS England (NHSE) launched the in-service evaluation (ISE) in September 2021.

Interim data from the first 21 months of this ISE is encouraging and is summarised later in this article.

On the recommendation of the UK NSC:

NHSE and the DHSC have agreed to extend the evaluation until the end of March 2024, rather than September 2023 as originally planned.

About SCID

SCID is the name for a group of rare conditions that affect the immune system and make it very hard for babies to fight off common infections. Without bone marrow transplant treatment, babies with SCID usually die before they are a year old, and treatment is more likely to be successful if SCID is detected early.

About a third of babies with SCID are diagnosed because another member of their family has the condition. Without screening, the remaining affected babies are usually diagnosed only when they become ill.

Life-changing benefits of newborn screening

Wednesday, 28 June, marks International Neonatal Screening Day, celebrating the birthday of microbiologist Dr Robert Guthrie, who introduced the paper blood spot card and a newborn screening test for phenylketonuria (PKU) in the 1960s.

Dr Guthrie’s work revolutionised the early asymptomatic detection of treatable rare conditions and laid the foundation for newborn blood spot (NBS) screening programmes worldwide. The NHS NBS Screening Programme currently tests for 9 rare but serious conditions and provides life-changing benefits for children who are identified and treated before these conditions can cause irreversible damage.

SCID could become the tenth NBS condition if results from the ISE reassure the UK NSC that screening does more good than harm at reasonable cost.

Interim ISE results

The NHS invites and screens for SCID around two-thirds of the newborn population of England in the areas covered by the ISE.

An estimated 635,000 babies were screened for SCID during the first 21 months of the evaluation (6 September 2021 to 31 May 2023).

As a result, 399 babies were referred with abnormal results. 10 of these were found to have SCID. Two of the 10 had already been identified because members of their family were affected, so the remaining 8 were diagnosed early thanks to screening.

While around half of the babies referred did not have any problems with their immune system on further testing, some were found to have other immunological conditions causing low white blood cell counts.

The ISE is being extended to collect more data because fewer babies with SCID have been detected than had been anticipated. The testing process has been more complicated and difficult than expected, so the extension of the ISE also gives more time for new approaches to be tested.

Evaluation improves screening pathway and addresses important questions

The ISE is proving of huge value in helping to determine the optimum way to screen for SCID.

During the past year, the NHSE-led ISE team has been reviewing the data to change the way in which positive results are calculated. This has helped reduce the number of false positive results – and associated anxiety for parents – without missing any babies with SCID.

Data from the ISE will help answer questions about the effectiveness of NHS screening for SCID in England compared to the way babies are detected without screening.

These questions include:

  • how many babies are born each year with SCID
  • how well babies get on if they are diagnosed early
  • how long babies found by screening stay in hospital if they are diagnosed early
  • the percentage of SCID babies who would be diagnosed because they have an affected family member
  • the impact of screening on families – for example, how worried they are, how many babies need more tests, how many other conditions are detected and is that beneficial, and how many babies have unnecessary tests and treatments
  • the ability of NHS services to deliver screening, including workforce implications for specialised teams
  • the cost of the test

The ISE is also conducting research to gather opinions on the impact of screening on the public and health care professionals. This will include insights from parents of unaffected babies, babies given false positive results and babies with other conditions detected by screening.

Next steps

When the evaluation is complete, the ISE team will submit a report to the UK NSC. This will include the views of patient representatives, academics, doctors, nurses and commissioners.

The UK NSC will review the report, take the advice of its newborn screening experts and consult for 3 months before making a recommendation to ministers on whether SCID should become part of the NHS NBS Screening Programme in the UK.

Thanks to all involved

The planning and delivery of the ISE has involved the hard work of many health care professionals, including midwives, laboratory staff, paediatricians, child health services, modellers, statisticians commissioners, immunisation leads and IT experts.

One of the team’s biggest challenges was having to change the neonatal BCG vaccination programme in England because BCG can make the treatment for SCID more complicated. The BCG vaccination is now given at around 6 weeks, after babies have received their SCID results. The UK Health Security Agency is monitoring, with NHSE, any potential impacts of the ISE on neonatal BCG vaccination services.

Many thanks to all involved and we will keep you updated on progress with the ISE via this blog.

Keep up to date

The UK NSC blog provides up to date news from the UK National Screening Committee. You can register to receive updates direct to your inbox, so there’s no need to keep checking for new articles. If you have any questions about this blog article, or about the work of the UK NSC, email

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