The route into epidemiologist

Disease at population scale, usually via a master's in public health — one of the strongest routes from this degree.

Three to four years, with a laboratory or research year common and worth taking.

Public health laboratory work and surveillance, a natural move via a public health master's.

Four years plus an internship year in the Saudi system; three to four years in the UK with accredited training.

Health data at population scale, usually via a master's.

Three to four years in the UK, four to five in the Kingdom and the US.

Not a direct route, and environmental exposure work sits between the two fields.

Three to four years, with fieldwork throughout and a mapping project that is often the defining piece of work.

Environmental health — exposure, air quality and their population consequences.

Three to four years, usually with fieldwork and often a placement.

A common move out of clinical practice and into disease at population scale.

Five to six years undergraduate outside North America; four years of medical school after a first degree in the US and Canada. Then residency, which is where the real length is.

A common route out of direct care, via a master's in public health.

Three to four years, roughly half of it spent on clinical placement rather than in lectures, plus an internship year in the Saudi system.

Pharmacoepidemiology — studying what medicines do across whole populations rather than one patient.

Four to six years depending on the country, plus a pre-registration or internship year before licensure.

Population rehabilitation and disability research, via a public health master's.

Four to five years plus an internship year in the Saudi system; three to four years in the UK. Some countries, notably the US, now require a doctoral-level qualification.

Mental health epidemiology and population research, via a public health master's.

Three to four years for the degree. Clinical practice requires postgraduate training on top, typically three or more further years and highly competitive.

Imaging-based screening programmes and population studies, usually via a public health master's.

Four years plus an internship year in the Saudi system; three to four years in the UK. Licensed practice follows immediately.

Biostatistics is the largest employer of statisticians and the most direct health route.

Three to four years for the bachelor's, plus a master's that is close to an entry requirement rather than an advantage.

Zoonotic disease and population health, where veterinary training is genuinely valued and under-supplied.

Five to six years undergraduate outside North America; four years after a first degree in the US and Canada.

Cambridge natural sciences; most universities require no test for biology.

• July to SeptemberUCAT testing window, sat at a test centre.
• September to JanuaryLNAT testing window for most law courses.
• OctoberMost Oxford and Cambridge subject tests — TMUA, ESAT, PAT, TSA.
• JuneSTEP, sat alongside A-Levels as a condition of a Cambridge or Warwick offer rather than for shortlisting.

The Saudi admission composite for science and health colleges.

• Several periods across the yearQudurat (General Aptitude Test), open from Grade 11. Computer-based and paper sittings both run.
• Final months of the school yearTahsili (Scholastic Achievement Test), sat near the end of Grade 12 once the syllabus is covered.
• Spring and summer of Grade 12University applications through the unified admission portals and each university's own portal.

The licence to practise, with the classification level following your qualification and setting both your scope and your pay.

Not a test, and the thing most likely to go wrong. A biology or biomedical science degree that is not accredited for clinical practice will not license you — check this before enrolling, because it cannot be fixed afterwards.

Required or advantageous at several UK universities for mathematical computing and economics courses.

• July to SeptemberUCAT testing window, sat at a test centre.
• September to JanuaryLNAT testing window for most law courses.
• OctoberMost Oxford and Cambridge subject tests — TMUA, ESAT, PAT, TSA.
• JuneSTEP, sat alongside A-Levels as a condition of a Cambridge or Warwick offer rather than for shortlisting.

For US applications; the mathematics section is read specifically for quantitative majors.

• March, May, JuneSpring sittings. The standard first attempt, in Grade 11.
• August, October, November, DecemberAutumn sittings. The second attempt, and the last one that reaches early US deadlines is usually the October or November date.
• Two to four weeks after each sittingScores released; sending them to universities is a separate step with its own timing.

Environmental science rarely requires a subject admissions test anywhere, which makes this one of the least administratively demanding science applications.

Required by most UK medical and dental schools, and several rank applicants on it directly. Booking closes in September, weeks before the mid-October application deadline.

• July to SeptemberUCAT testing window, sat at a test centre.
• September to JanuaryLNAT testing window for most law courses.
• OctoberMost Oxford and Cambridge subject tests — TMUA, ESAT, PAT, TSA.
• JuneSTEP, sat alongside A-Levels as a condition of a Cambridge or Warwick offer rather than for shortlisting.

Frequently the heaviest single component of the Saudi health-college admission composite.

• Several periods across the yearQudurat (General Aptitude Test), open from Grade 11. Computer-based and paper sittings both run.
• Final months of the school yearTahsili (Scholastic Achievement Test), sat near the end of Grade 12 once the syllabus is covered.
• Spring and summer of Grade 12University applications through the unified admission portals and each university's own portal.

Sit it early; the best score counts and an early attempt is diagnostic.

• Several periods across the yearQudurat (General Aptitude Test), open from Grade 11. Computer-based and paper sittings both run.
• Final months of the school yearTahsili (Scholastic Achievement Test), sat near the end of Grade 12 once the syllabus is covered.
• Spring and summer of Grade 12University applications through the unified admission portals and each university's own portal.

The US graduate-entry route. Nothing you do at seventeen prepares for it directly, and it is worth knowing the road has this on it.

Nursing regulators in the UK, Australia and the Gulf often require a higher English score than the university did — check the regulator's requirement, not just the university's.

• Weekly, year-roundIELTS and TOEFL both run frequently at centres across the Kingdom; Duolingo and PTE can be sat at very short notice.
• 3 to 13 days after the testResults, depending on the test. IELTS computer-delivered is among the fastest; paper-based is slower.
• Autumn of Grade 12 at the latestWhen to have sat it by, leaving room for one repeat before offers are decided.

Requirements vary by PharmD programme and several have dropped standardised testing.

Not a formal test at most programmes, and a genuine requirement of the work — this is a physically demanding profession and the placement year makes that clear quickly.

Not a test, and the real gate for clinical training. Assistant psychologist and support work posts are what competitive applicants have, and they take years to accumulate.

The real gate for this profession. Around seven in ten statisticians hold a master's or doctorate, so plan the bachelor's with that in mind.

Not a test, and a harder requirement than any test on this page. Most veterinary schools want weeks of experience across more than one setting — practice, farm, kennels, stables — and will not consider an application without it. It cannot be acquired in the month before the deadline.

Frequently multiple mini-interviews, and heavily weighted.