By: Dr Ed Parker, Assistant Professor and Co-Director of the Vaccine Centre at the London School of Hygiene & Tropical Medicine (LSHTM)

And so another COVID-19 booster campaign begins in the UK. As winter approaches, and an under-pressure health system prepares to weather the storm ahead, our friends, loved ones, colleagues, and carers who are most vulnerable to the SARS-CoV-2 virus are being offered an additional vaccine dose – fortifying their protection against this unpredictable foe.

Almost three years have passed since the first doses of COVID-19 vaccines were administered in the UK. It is an opportune moment to take stock of things. I am part of a team of researchers using OpenSAFELY – a platform developed to deliver urgent research during the pandemic. To help paint a picture of what’s happened, we’ve recently published a snapshot of England’s vaccination history. How many doses of COVID-19 vaccine have people typically received? How long has passed since their most recent dose? And, crucially, how do these measures differ by age, ethnicity, socioeconomic status, and in different clinical risk groups?

The report stands as a testament to the achievements of the UK’s vaccination programme. On average, people over 75 years have received six doses, with 88% vaccinated within the past 12 months. People aged 50–74 have received an average of four doses. Although under-50s have been eligible for fewer booster campaigns, over two-thirds have received at least two doses.

If the pandemic has blunted our response to health statistics such as these, we would do well to consider the myriad stories underlying them. These are stories of practice managers coordinating the logistical challenges of delivering multiple booster campaigns each year. Of individuals taking time out of their busy schedules to come forward and get vaccinated. And of nurses, GPs, and many others finding the right words for those in need of reassurance.

These vaccines have saved lives on a vast scale. Time and time again, studies have emphasised the protective effects of vaccination, including the incremental benefits of booster doses. For individuals with weakened immune systems, repetition is particularly important  – while the response to initial vaccine doses may fall short, the chance of responding grows with each additional dose.

As the SARS-CoV-2 virus has evolved to evade our protective immunity, the vaccines have been modified to keep up. The campaign this autumn is employing a combined vaccine that targets the original SARS-CoV-2 virus and the Omicron BA.4-5 variant. New vaccines targeting the XBB variant (which rose to prominence earlier this year) may become available over the course of the campaign. While the recent emergence of the BA.2.86 ‘Pirola’ variant prompted the start of autumn boosting to be brought forward as a “precautionary measure”, early signs suggest that the updated vaccines elicit a strong immune response to this latest viral permutation.

Yet significant challenges remain. Worryingly, differences in vaccine uptake according to ethnicity and socioeconomic status remain as stark now as they did in the early days of the vaccine rollout. Based on the latest OpenSAFELY report, the proportion of over-75s vaccinated within the last 12 months stands at 90% for White individuals, 67% for people of mixed ethnicity, 56% for South Asian individuals, and 49% for Black individuals. In the latter group, one out of every five are yet to receive a single vaccine dose.

Gaps in vaccine coverage are also seen in several vulnerable clinical subgroups. For example, the proportion of kidney transplant recipients unvaccinated in the past year is 28% among 50–64 year-olds and 50% in under-50s.

These issues go beyond COVID-19. Reports from the UK Health Security Agency highlight a continuing downward trend in routine vaccine uptake across the UK. While this trend persists, the risk of preventable illness will remain. Measles – a disease eliminated in England as recently as 2017 – is back on the rise, with over 140 confirmed cases since January.

The barriers facing vaccination come in many forms. For one person, the chance to be immunised may be missed due to the stresses of work, childcare, and other day-to-day commitments. For another person, the opportunity may be avoided over mistrust in vaccines and the institutes that develop them. How can we reach out more effectively to both of these individuals, and the many others who remain under-served by the vaccination programme?

There will be no easy fixes. Vaccines can be a victim of their own success, blunting not only the harmful effects of diseases but the fear that surrounds them. We must find more effective ways to communicate the individual and societal benefits of vaccination. Health services will also need financial, logistical, and strategic support to expand vaccine delivery and increase access amid the many competing challenges they are facing. Where possible, these efforts must be tailored to the needs and concerns of communities by partnering with trusted local organisations. And we must continue to seek creative solutions to enhance vaccine uptake through research that embraces insights from a variety of disciplines, from epidemiology to social science.

Three years in, the COVID-19 vaccine rollout has achieved so much. But the programme is a marathon rather than a sprint. We must keep striving to ensure that the benefits of vaccination can be shared by everyone.