Public Health: Screening programmes and health protection

🌍 Screening programmes and health protection. Screening offers tests to apparently healthy people to identify those at higher risk of a condition so that earlier treatment can improve outcomes. It can also do harm, through false positives, overdiagnosis and anxiety, so programmes in the UK are introduced only on the advice of the UK National Screening Committee. Health protection covers immunisation, infection control and environmental hazards. This chapter covers the criteria for screening, every UK national programme, and the practical health protection duties of a doctor.
Your four questions about any screening programme: Does it meet the screening criteria? What are the test, the eligible population and the interval? What are the harms (false positives, overdiagnosis)? Has the person made an informed choice?

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What Screening Is (and Is Not)

• Screening (UK NSC definition): a process of identifying apparently healthy people who may be at increased risk of a disease or condition, who can then be offered information, further tests and appropriate treatment to reduce their risk and/or complications.
• A screening test is not a diagnostic test - a positive result leads to diagnostic testing (e.g. colonoscopy after positive FIT).
• Population screening - offered systematically to a defined population with call and recall, quality assurance and failsafe processes.
• Opportunistic screening / case-finding - testing during unrelated consultations (e.g. BP checks, opportunistic chlamydia testing, AF pulse checks).
• Targeted screening - offered to higher-risk groups (e.g. lung cancer screening for people with a smoking history; prostate screening for BRCA2 carriers).

Wilson and Jungner and UK NSC Criteria

• Wilson and Jungner (WHO, 1968) - ten principles:
  • The condition should be an important health problem.
  • There should be an accepted treatment for patients with recognised disease.
  • Facilities for diagnosis and treatment should be available.
  • There should be a recognisable latent or early symptomatic stage.
  • There should be a suitable test or examination.
  • The test should be acceptable to the population.
  • The natural history of the condition should be adequately understood.
  • There should be an agreed policy on whom to treat as patients.
  • The cost of case-finding should be economically balanced in relation to possible expenditure on medical care as a whole.
  • Case-finding should be a continuing process, not a "once and for all" project.
• UK NSC criteria build on these and add that there should be evidence from high-quality RCTs that the programme is effective in reducing mortality or morbidity, that the benefit outweighs the physical and psychological harm, and that the programme is acceptable, cost-effective and deliverable with adequate quality assurance.

Benefits, Harms and Informed Choice

• Benefits: reduced mortality and morbidity, less radical treatment, reassurance for true negatives.
• Harms: false positives (anxiety, further invasive tests), false negatives (false reassurance, delayed presentation), overdiagnosis and overtreatment, complications of diagnostic tests (e.g. colonoscopy perforation about 1 in 1,500), opportunity costs.
• Breast screening example (Independent UK Panel, 2012): for every 10,000 women aged 50 invited for 20 years, about 43 breast cancer deaths are prevented and about 129 women are overdiagnosed - roughly 1 death prevented for every 3 overdiagnosed cases.
• Informed choice - people must receive balanced information (NHS leaflets) and may decline; screening is an offer, not an obligation.
• Screening biases (lead-time, length-time, overdiagnosis, healthy volunteer) - see the Diagnostic Tests chapter.
• Inequalities in uptake - lower in deprived areas, some ethnic minority groups, people with learning disabilities or serious mental illness; reasonable adjustments and targeted outreach are needed.

Adult Cancer Screening Programmes

Programme	Who (England)	Test	Interval
Breast	Women aged 50 to 71st birthday (can self-refer after 71); higher-risk women from younger ages (family history, chest radiotherapy)	Mammography (two views)	Every 3 years
Cervical	People with a cervix aged 25–64	HPV primary testing (cytology only if HPV positive)	Every 5 years aged 25–64 if HPV negative (England moved 25–49s from 3 to 5 years from July 2025); HPV positive with normal cytology → repeat HPV at 1 year
Bowel	Aged 50–74 (age extension from 60 completed in 2025); over 75 can self-refer	FIT home kit; threshold 120 µg Hb/g in England (80 in Scotland) → colonoscopy (or CT colonography)	Every 2 years
Lung	Aged 55–74 who have ever smoked - risk-assessed (lung health check), targeted	Low-dose CT	Every 2 years if eligible (national rollout under way, full coverage expected by about 2029–30)
Prostate	Men aged 45–61 with a BRCA2 variant and a family history of relevant cancer (UK NSC recommendation May 2026; accepted for England, rollout expected 2027)	PSA	Every 2 years

• Bowel scope (one-off flexible sigmoidoscopy at 55) was discontinued in England in 2021.
• Cervical screening results pathway: HPV negative → routine recall; HPV positive + abnormal cytology → colposcopy; HPV positive + normal cytology → repeat in 12 months (colposcopy if still positive after two repeats).
• HPV vaccination (single dose since 2023) is expected to reduce cervical cancer greatly; screening continues for vaccinated cohorts.
• Bowel screening outcomes: around 2% of FIT kits are positive; about 1 in 10 of those has cancer and more have polyps removed.

Other Adult Screening Programmes

Programme	Who	Test	Notes
Abdominal aortic aneurysm (AAA)	Men in their 65th year (older men can self-refer)	One-off abdominal ultrasound	<3.0 cm normal; 3.0–4.4 cm annual scan; 4.5–5.4 cm 3-monthly; ≥5.5 cm refer to vascular surgery (seen within 2 weeks); also refer if growing >1 cm/year or symptomatic
Diabetic eye screening	People with diabetes aged 12 and over	Digital retinal photography	Annual; 2-yearly for low-risk people (no retinopathy on two consecutive screens)
NHS Health Check (not a UK NSC programme - a local authority prevention programme)	Aged 40–74 without existing CVD, diabetes, CKD or hypertension	BP, BMI, cholesterol, QRISK, AUDIT-C, physical activity, dementia awareness (65+)	Every 5 years
AF	Not recommended as a national screening programme (UK NSC) - opportunistic pulse checks instead	-	-

• Learning disability annual health checks (age 14+) and severe mental illness physical health checks are prevention programmes rather than UK NSC screening.

Antenatal and Newborn Screening

• Antenatal (offered to all pregnant women):
  • Infectious diseases - HIV, hepatitis B and syphilis (at booking; repeat offered later if declined).
  • Sickle cell and thalassaemia - by 10 weeks (family origin questionnaire; partner testing if carrier).
  • Fetal anomaly - dating scan; combined test at 11+2 to 14+1 weeks (nuchal translucency, PAPP-A, hCG) for Down's (T21), Edwards' (T18) and Patau's (T13) syndromes; quadruple test at 14+2 to 20+0 weeks if too late for the combined test; higher-chance result → offered NIPT (cell-free fetal DNA) or diagnostic test (CVS or amniocentesis, about 0.5% miscarriage risk); anomaly scan at 18+0 to 20+6 weeks (11 conditions including spina bifida, anencephaly, serious cardiac abnormalities, cleft lip, gastroschisis, exomphalos).
  • Gestational diabetes - OGTT for women with risk factors (BMI >30, previous macrosomic baby ≥4.5 kg, previous GDM, family history of diabetes, high-risk ethnicity).
  • Blood group and antibodies (rhesus D) and full blood count.
• Newborn:
  • Newborn and infant physical examination (NIPE) within 72 hours and at 6–8 weeks (eyes, heart, hips, testes).
  • Newborn hearing screening (automated otoacoustic emissions, then auditory brainstem response if needed).
  • Newborn blood spot on day 5 - nine conditions: sickle cell disease, cystic fibrosis, congenital hypothyroidism, and six inherited metabolic diseases (PKU, MCADD, MSUD, isovaleric acidaemia, glutaric aciduria type 1, homocystinuria). SCID screening has been evaluated in England.

Conditions Not Screened For - and Why

• Population prostate cancer screening - PSA has poor specificity; screening causes overdiagnosis and overtreatment with modest mortality benefit (UK NSC 2026 recommended against screening all men).
• Ovarian cancer - the UKCTOCS trial (CA125 and ultrasound) showed no reduction in mortality.
• Thyroid cancer - screening in South Korea led to a large rise in diagnosis with no change in mortality (overdiagnosis).
• Neuroblastoma - infant screening trials detected regressing tumours without reducing mortality.
• Population AF, dementia and ovarian cancer screening - not recommended; evidence of benefit lacking or harms unclear.
• Whole-body CT or commercial "health MOTs" - high rates of incidental findings and false reassurance; not recommended.

Immunisation Policy and Programmes

• JCVI advises; UKHSA implements; the Green Book (Immunisation against infectious disease) is the clinical reference.
• Types of vaccine: live attenuated (MMR/MMRV, rotavirus, BCG, LAIV nasal flu, yellow fever, oral typhoid), inactivated (IPV, hepatitis A, rabies), subunit/toxoid (diphtheria, tetanus, acellular pertussis, hepatitis B, HPV), conjugate (Hib, PCV, MenACWY - protein conjugation produces T-cell-dependent responses in infants), mRNA (COVID-19, RSV in some products), viral vector.
• Live vaccines are contraindicated in significant immunosuppression and pregnancy; give two live vaccines on the same day or 4 weeks apart (rule now limited to specific combinations - check the Green Book).
• Coverage targets: WHO recommends ≥95% for MMR; UK coverage of the second MMR dose has been below 90% in recent years, with measles outbreaks in England in 2024–25.
• Vaccine hesitancy (WHO "3 Cs": confidence, complacency, convenience) - address with respectful conversation, evidence and easy access.
• Adult and seasonal programmes: influenza (65+, clinical risk groups, pregnant women, health and social care workers, children aged 2 to school Year 11 via nasal LAIV), COVID-19 (seasonal for older and high-risk groups), pneumococcal (65+ and risk groups), shingles (Shingrix - from age 65 in cohorts, 70–79, and immunosuppressed adults from 18), RSV (pregnancy from 28 weeks to protect infants; adults 75–79), pertussis in pregnancy (16–32 weeks).
• Occupational immunisation for healthcare workers - hepatitis B (check anti-HBs response), MMR, varicella (if non-immune), BCG (if at risk), influenza and COVID-19.
• Post-exposure prophylaxis: rabies, hepatitis B (vaccine ± HBIG), tetanus-prone wounds, measles (MMR within 72 hours or HNIG within 6 days for vulnerable contacts), varicella (VZIG or antivirals for susceptible pregnant women and immunosuppressed people), meningococcal contacts (ciprofloxacin).

Infection Prevention and Control

• Standard infection control precautions (for all patients): hand hygiene (WHO 5 moments - before patient contact, before aseptic task, after body fluid exposure risk, after patient contact, after touching patient surroundings), PPE, respiratory hygiene, safe sharps, safe management of the environment, linen and waste, occupational exposure management.
• Transmission-based precautions: contact (gloves, apron - MRSA, C. difficile), droplet (fluid-resistant surgical mask), airborne (FFP3 respirator with fit testing, negative-pressure room - TB, measles, chickenpox).
• Hand hygiene: alcohol hand rub is effective for most organisms, but soap and water are needed for C. difficile spores and norovirus.
• Healthcare-associated infections: C. difficile (antimicrobial stewardship - avoid the "4 Cs": cephalosporins, co-amoxiclav, clindamycin, ciprofloxacin; isolate; stop PPIs if possible), MRSA (screening, decolonisation), Gram-negative bloodstream infections (catheter care), surgical site infections, CPE (carbapenemase-producing Enterobacterales).
• Antimicrobial resistance (AMR) - the UK national action plan (2024–2029); stewardship ("Start smart, then focus"), reducing unnecessary prescribing, infection prevention, vaccination, surveillance.
• Needlestick injury: encourage bleeding, wash with soap and water, report to occupational health, risk-assess the source (HIV, hepatitis B and C); HIV PEP within 72 hours (ideally within 1 hour) for significant exposures; hepatitis B booster/HBIG according to immunity; baseline and follow-up testing.

Tuberculosis Control

• Incidence in England is about 8–9 per 100,000 and rising since 2021; most cases are in people born outside the UK, and rates are highest in deprived urban areas and among people experiencing homelessness, prisoners and people who use drugs.
• Notify all cases on suspicion; contact tracing (household and close contacts screened with IGRA/Mantoux and CXR).
• Treatment: 6 months (2 months rifampicin, isoniazid, pyrazinamide and ethambutol; then 4 months rifampicin and isoniazid); longer for CNS TB; directly observed therapy (DOT) or video-observed therapy for those at risk of non-adherence.
• Latent TB infection testing and treatment for new entrants aged 16–35 from high-incidence countries (≥150 per 100,000), contacts, and people starting immunosuppression (e.g. anti-TNF).
• Pre-entry TB screening for UK visa applicants from high-incidence countries.
• Infection control: smear-positive pulmonary TB is infectious - isolate (negative pressure for MDR-TB) until 2 weeks of effective treatment and clinical improvement.

Environmental Hazards and Emergency Preparedness

• Air pollution - the largest environmental risk to public health in the UK; fine particulate matter (PM2.5) and NO₂ contribute to an estimated 29,000–43,000 deaths a year; linked with asthma, COPD, CVD, lung cancer and low birth weight. The coroner's verdict in the death of Ella Adoo-Kissi-Debrah (2020) was the first in the UK to list air pollution.
• Climate change - heatwaves (older people, chronic disease, medicines that impair thermoregulation such as diuretics and antipsychotics), flooding, vector-borne disease changes, food security.
• Cold homes - excess winter deaths (CVD, respiratory illness), damp and mould (asthma, respiratory infections in children).
• Carbon monoxide - headache, nausea, dizziness, often several household members or pets affected; check COHb; high-flow oxygen.
• Radon - second leading cause of lung cancer after smoking; high-radon areas (e.g. Cornwall, Derbyshire); home testing and remediation.
• Chemical, biological, radiological and nuclear (CBRN) incidents, pandemic planning, and the Civil Contingencies Act 2004 (NHS organisations are category 1 responders).

Travel Health and Imported Infection

• Pre-travel advice: vaccines (hepatitis A, typhoid, yellow fever at certified centres, rabies, Japanese encephalitis, tick-borne encephalitis, meningococcal ACWY for Hajj), malaria prevention (ABCD: Awareness, Bite prevention, Chemoprophylaxis, prompt Diagnosis), food and water hygiene, sexual health, venous thromboembolism, travel insurance.
• Fever in a returning traveller - malaria until proven otherwise (falciparum within 3 months of travel to an endemic area): three negative thick and thin films or RDTs 12–24 hours apart are needed to exclude it.
• Viral haemorrhagic fever - risk assessment if fever within 21 days of travel to an affected area (Ebola, Lassa, Marburg, CCHF); isolate and involve infectious diseases and UKHSA.
• Other imported infections: dengue, enteric fever (typhoid), rickettsial infection, schistosomiasis, amoebic liver abscess, TB, HIV, MERS (Middle East travel with respiratory illness).

Screening at a Glance

Programme	Who	Test and interval
Breast	Women 50–71	Mammogram, 3-yearly
Cervical	25–64	HPV primary, 5-yearly
Bowel	50–74	FIT (≥120 µg/g), 2-yearly
Lung	55–74 ever-smokers (risk-assessed)	Low-dose CT
AAA	Men in 65th year	One-off ultrasound; refer ≥5.5 cm
Diabetic eye	Diabetes, 12+	Retinal photos, annual (2-yearly low risk)
Prostate (targeted)	BRCA2 carriers with family history, 45–61	PSA, 2-yearly (from 2027)
Newborn blood spot	Day 5	Nine conditions

Spot the Answer

• A 66-year-old man's screening scan shows a 5.6 cm AAA. → Refer to vascular surgery (seen within 2 weeks) for repair assessment.
• A woman of 32 has HPV detected with normal cytology. → Repeat HPV test in 12 months.
• Twenty-year survival from cancer improves after screening is introduced but mortality is unchanged. → Lead-time bias and overdiagnosis.
• Which hand hygiene for a patient with C. difficile? → Soap and water (alcohol does not kill spores).
• A nurse has a needlestick from an HIV-positive source. → HIV PEP as soon as possible (ideally within 1 hour, up to 72 hours).
• Measles coverage target? → 95% (herd immunity threshold about 93–95%).

Exam-style Scenarios

• Scenario. A 52-year-old woman asks whether she should have a CA125 test "to screen for ovarian cancer" as she has no symptoms.
  Answer: Ovarian cancer screening is not recommended - the UKCTOCS trial showed no mortality benefit, and false positives lead to surgery. Discuss symptoms to watch for, and refer for assessment of familial risk if there is a family history (BRCA testing).
• Scenario. A health board must decide whether to start screening for a newly treatable rare metabolic disorder. What questions should be asked?
  Answer: Apply the Wilson–Jungner/UK NSC criteria: important condition, detectable early stage, accurate and acceptable test, effective early treatment better than later treatment, RCT or strong evidence of benefit, harms of false positives, cost-effectiveness, capacity for diagnosis and treatment, and quality assurance.
• Scenario. An unvaccinated 30-year-old pregnant woman is in contact with chickenpox at 20 weeks; she does not recall having had it.
  Answer: Check VZV IgG urgently. If non-immune, offer post-exposure prophylaxis (oral antivirals from day 7 to 14 after exposure, or VZIG per current UKHSA guidance), advise urgent review if a rash develops, and avoid contact with other pregnant women. Varicella vaccine is live and contraindicated in pregnancy.

Key Points

• Screening is offered to healthy people; it must do more good than harm, judged by the UK NSC.
• Know the UK programmes: breast 50–71 (3-yearly), cervical 25–64 HPV (5-yearly), bowel FIT 50–74 (2-yearly), AAA men at 65, lung CT 55–74 ever-smokers, targeted prostate screening for BRCA2 carriers.
• Informed choice is essential; overdiagnosis is a real harm.
• Herd immunity, high vaccine coverage and the Green Book underpin immunisation.
• Soap and water for C. difficile and norovirus; FFP3 for airborne infections.

Guidelines and Further Reading

• UK National Screening Committee: criteria for a population screening programme; current recommendations (including prostate cancer, 2026)
• Wilson JMG, Jungner G. Principles and practice of screening for disease. WHO 1968
• NHS England: population screening programmes (breast, cervical, bowel, AAA, diabetic eye, antenatal and newborn)
• Independent UK Panel on Breast Cancer Screening. Lancet 2012
• UKHSA: Immunisation against infectious disease (the Green Book); routine immunisation schedule
• NHS England: National infection prevention and control manual (NIPCM)
• NICE NG33: Tuberculosis
• UK Government: Confronting antimicrobial resistance 2024 to 2029
• UKHSA: Chief Medical Officer's annual report 2022 (air pollution)