What is the Gera Immunity Gap Score?

The Gera Immunity Gap Score (GIGS) is a Gera Systems measure of how far an area's vaccination coverage falls below full uptake. The flu variant is 100 minus over-65 flu uptake per ICB; the childhood variant is 100 minus a weighted average of MMR1, MMR2 and 6-in-1 coverage per local authority. A higher score means a wider immunity gap. It uses only real UKHSA and NHS England data under the Open Government Licence v3.0.

Why two variants instead of one combined score?

The cited sources publish flu uptake cleanly by Integrated Care Board (42 ICBs) and childhood coverage by upper-tier local authority (149 areas) — different geographies and different years. Rather than force them onto one mismatched map or invent missing values, Gera publishes a flu Immunity Gap per ICB and a childhood Immunity Gap per local authority, each on its own real data. No number is estimated to fill a gap.

Is the score reproducible?

Yes. Every input is a real, published figure: UKHSA flu uptake in GP patients (2024–25) and NHS England / UKHSA COVER childhood coverage (2023–24), both OGL v3.0. The formulae above are the complete calculation — anyone can download the same files and reproduce every score exactly. Gera invents no numbers.

Which area has the widest immunity gap?

On the latest data, the widest flu Immunity Gap among ICBs is North East London (39.6/100, from 60.4% over-65 flu uptake), and the widest childhood Immunity Gap among local authorities is Hackney and City of London (29.9, from 78.2% MMR1 coverage). See their pages for the full figures.

Does a high score mean an area is unsafe?

No. The score measures the population-level vaccination gap, which is driven by access, eligibility, demographics and confidence — not the quality of local services. It is an area-wide figure, never a prediction for any individual. If you or your child have missed a vaccine, a GeraClinic clinician can advise and arrange catch-up vaccination.

Gera Immunity Gap Score — Methodology

The complete, reproducible formula behind the Gera Immunity Gap Score, computed only from real UKHSA and NHS England vaccination data.

The formulae

GIGS_flu = 100 − flu_uptake_65plus (per ICB)

GIGS_child = 100 − (0.5·MMR1_5y + 0.3·MMR2_5y + 0.2·SixInOne_12m) (per local authority)

A higher score means a wider gap below full coverage. England-level scores use the national uptake figures (74.9% flu over-65; 91.9% MMR1 at 5).

Step by step

Take the real source figures. Read the published uptake percentages: UKHSA flu vaccine uptake in GP patients for the 2024–25 season (per ICB) and NHS England / UKHSA COVER childhood coverage for 2023–24 (per local authority). Each childhood coverage % is the published numerator (vaccinated) ÷ denominator (eligible population) × 100. No estimates are introduced.
Compute the flu Immunity Gap (per ICB). Gera Immunity Gap Score (flu) = 100 − flu vaccine uptake among GP patients aged 65 and over (%). A higher score means a wider gap below full coverage.
Compute the childhood Immunity Gap (per local authority). Gera childhood Immunity Gap = 100 − (0.5 × MMR1 at 5 years + 0.3 × MMR2 at 5 years + 0.2 × 6-in-1 at 12 months), each as a percentage. The weights prioritise first-dose measles protection while still rewarding completion of the second dose and the primary 6-in-1 course.
Read against the targets. Compare each score to the relevant benchmark: the WHO 75% flu target for older adults and the WHO 95% two-dose MMR target for measles herd immunity. The score is published per ICB (flu) and per local authority (childhood); England-level scores use the national uptake figures.

Widest immunity gaps

Widest Gera Immunity Gap — flu (by ICB) and childhood (by local authority)
Area	Type	Headline coverage	Gera Immunity Gap
North East London	Flu (ICB)	60.4% over-65 flu	39.6 / 100
Hackney and City of London	Childhood (LA)	78.2% MMR1 at 5	29.9

Computed across 42 ICBs (flu) and 149 local authorities (childhood).

Why this score, and what it is not

Headline uptake percentages are easy to quote but hard to compare across areas and vaccines. The Gera Immunity Gap Score restates coverage as the distance below full protection, so a wider gap is always the larger number. It measures the population-level vaccination gap — driven by access, eligibility, demographics and confidence — not the quality of local services, and it is an area-wide figure, never a prediction for any individual.

Gera Immunity Gap Score: frequently asked questions

What is the Gera Immunity Gap Score?: The Gera Immunity Gap Score (GIGS) is a Gera Systems measure of how far an area's vaccination coverage falls below full uptake. The flu variant is 100 minus over-65 flu uptake per ICB; the childhood variant is 100 minus a weighted average of MMR1, MMR2 and 6-in-1 coverage per local authority. A higher score means a wider immunity gap. It uses only real UKHSA and NHS England data under the Open Government Licence v3.0.
Why two variants instead of one combined score?: The cited sources publish flu uptake cleanly by Integrated Care Board (42 ICBs) and childhood coverage by upper-tier local authority (149 areas) — different geographies and different years. Rather than force them onto one mismatched map or invent missing values, Gera publishes a flu Immunity Gap per ICB and a childhood Immunity Gap per local authority, each on its own real data. No number is estimated to fill a gap.
Is the score reproducible?: Yes. Every input is a real, published figure: UKHSA flu uptake in GP patients (2024–25) and NHS England / UKHSA COVER childhood coverage (2023–24), both OGL v3.0. The formulae above are the complete calculation — anyone can download the same files and reproduce every score exactly. Gera invents no numbers.
Which area has the widest immunity gap?: On the latest data, the widest flu Immunity Gap among ICBs is North East London (39.6/100, from 60.4% over-65 flu uptake), and the widest childhood Immunity Gap among local authorities is Hackney and City of London (29.9, from 78.2% MMR1 coverage). See their pages for the full figures.
Does a high score mean an area is unsafe?: No. The score measures the population-level vaccination gap, which is driven by access, eligibility, demographics and confidence — not the quality of local services. It is an area-wide figure, never a prediction for any individual. If you or your child have missed a vaccine, a GeraClinic clinician can advise and arrange catch-up vaccination.

Explore the data

Contains public sector information published by UK Health Security Agency and licensed under the Open Government Licence v3.0. Source: UKHSA — Seasonal influenza vaccine uptake in GP patients in England, winter season 2024 to 2025 (2024–25 flu season (1 Sep 2024 – 28 Feb 2025), published 22 May 2025).

Contains public sector information published by NHS England Digital / UKHSA and licensed under the Open Government Licence v3.0. Source: NHS England — Childhood Vaccination Coverage Statistics, England, 2023-24 (COVER) (2023–24 (year ending 31 March 2024), published 17 September 2024).