Throughout the pandemic, the UK’s covid-19 data systems have been guiding global as well as local policies. The well-established health information systems combined with the more recently established National Immunisation Management System in England provided timely information on infections, emergence of new variants, and the value of different interventions. But one of the most important contributions from the UK came from the ability to rapidly track vaccine effectiveness.
Vaccination is the best method for societies to reduce the severity of illness and number of deaths from covid-19; and to start to return to a more normal way of living, working, and studying. But vaccination programmes need to be evidence-based, so that vaccines and healthcare resources are used appropriately, and there is equitable vaccine delivery. The covid-19 pandemic has shown the importance of data from medical records and the National Immunisation Management System in guiding national vaccination policies. Clinical trials can provide initial data on the efficacy and safety of vaccines. However, because of their relatively small size and short duration of follow-up, they cannot provide longer-term data on vaccine effectiveness or on rare adverse events. Furthermore, because covid-19 vaccines were designed to target the original strain of SARS-CoV-2, the trials are also unable to provide data on protection against new variants that emerged after the trials were completed. Nor were they able to provide data on the need for booster doses of vaccines to maintain protection from serious illness and death.
Clinical trials are also generally unable to provide data on smaller subgroups of the population such as people who are immunocompromised; or how different vaccines compare in their long-term safety and effectiveness. This data has to largely come from national immunisation systems and from medical records, as does data on vaccine uptake in different groups of the population. These are areas where the UK has excelled during the covid-19 pandemic in work led by government organisations such as the UK Health Security Agency and the UK Office for National Statistics.
In England, the UK Health Security Agency has assessed vaccine effectiveness against symptomatic covid-19 infection using community testing data linked to vaccination data from the National Immunisation Management System (NIMS); with further linkage to data from electronic NHS secondary care datasets; sequencing and genomics data; travel information; and mortality records. These data have allowed analysis of how well covid-19 vaccines protect against outcomes such as hospitalisation and death as well as against symptomatic infection during the course of the pandemic. With the linkage of secondary care datasets and NIMS data, it has also allowed for timely epidemiological safety signal assessments to be rapidly carried out in response to passive reports of adverse events after vaccination from the MHRA yellow card system. The large size of the English population allows for more precise estimation of these effects; something that is not always possible in data from countries with smaller health systems. Data from the UK also allowed identification of people at highest risk from the complications of covid-19, which helped in deciding which groups would be prioritised for vaccination. UK data also allowed the tracking of breakthrough infections following vaccination better than any other country; and confirmed that delaying the second dose of vaccine was likely to lead to better protection from serious illness.
Most recently, the data has allowed analysis of how well vaccines protect against new variants of SARS-CoV-2 such delta and omicron. The latest data confirm that three doses of vaccines provide good protection from hospitalisation and death from an omicron infection; but that the level of protection is not as high as against the delta variant that was previously predominant in many parts of the world.  Protection against infection is also less against newer variants than against the original strain of SARS-CoV-2, which meant that breakthrough infections in vaccinated people were common, particularly at times when community infection rates are high. The data also show that longer-term protection is better with the mRNA vaccines in use in the UK (Pfizer-BioNTech and Moderna) than with the AstraZeneca viral vector vaccine. Ongoing work will show how well this protection from serious illness and death is maintained; and whether further booster doses may be needed in the population more widely after the implementation of a fourth dose in older people and the clinically vulnerable. In addition, epidemiological assessments of safety signals will continue to support and maintain confidence in the covid-19 vaccine programme.
Other data can be linked to the NIMS to allow estimation of vaccine uptake by age group, area of England and by ethnic group. This has proved essential in identifying population groups and geographical areas with lower than average vaccine uptake. For example, the data has shown that vaccine uptake is generally lower in younger age groups than among older people; and lower in large, urban areas such as London than in other parts of England. The development of a public-facing “data dashboard” has allowed easy viewing of this data at national, local and regional level; thereby supporting public health teams to identify areas and communities with lower vaccine uptake.
Looking forward, it is important that we maintain our data collection, linkage, analysis and publication abilities for the longer-term. Although we must now all learn to live with covid-19, SARS-CoV-2 will still pose a threat to global health for some time, especially if new escape variants emerge. Furthermore, with population-level immunity after vaccination waning and covid-19 control measures ending, there is a risk that later in the year we may see a surge in infections in the UK and elsewhere; in recent weeks, we have already seen an increase in covid-19 infections and hospital admissions in the UK. In addition, changes in testing behaviour and guidance may affect how vaccine effectiveness is monitored in the future. The data systems, scope for data linkage, and the analytical capacity in the UK will prove essential in tackling the long-term threat to global public health from covid-19; and lessons from the UK’s data systems should continue to be shared with the rest of the world to support the global response to covid-19.
Azeem Majeed, Elise Tessier, Julia Stowe, Ali Mokdad
A version of this article was first published in the British Medical Journal.
- Majeed A, Molokhia M. Vaccinating the UK against covid-19. BMJ. 2020 Nov 30;371:m4654. doi: 10.1136/bmj.m4654.
- Majeed A, Papaluca M, Molokhia M. Assessing the long-term safety and efficacy of COVID-19 vaccines. Journal of the Royal Society of Medicine. 2021;114(7):337-340.
- Monitoring reports of the effectiveness of COVID-19 vaccination.https://www.gov.uk/guidance/monitoring-reports-of-the-effectiveness-of-covid-19-vaccination
- Andrews N, Stowe J, Kirsebom F, et al. Covid-19 Vaccine Effectiveness against the Omicron (B.1.1.529) Variant. N Engl J Med. 2022 Mar 2. doi: 10.1056/NEJMoa2119451.
- Walker P, David N. UK: over-75s and vulnerable people to be offered additional Covid booster jab.https://www.theguardian.com/society/2022/feb/21/uk-older-vulnerable-people-to-be-offered-covid-booster-vaccine
- Office for National Statistics. Coronavirus (COVID-19) latest insights: Vaccines.https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/conditionsanddiseases/articles/coronaviruscovid19latestinsights/vaccines
- Official UK government website for data and insights on coronavirus (COVID-19).https://coronavirus.data.gov.uk/
- Tapper J. Dismay as funding for UK’s ‘world-beating’ Covid trackers is axed.https://www.theguardian.com/world/2022/mar/12/dismay-as-funding-for-uks-world-beating-covid-trackers-is-axed
- Murray CH, Mokdad AH. After the Mandates End. Preparing for the next COVID-19 variant.https://www.thinkglobalhealth.org/article/after-mandates-end
- Dowd JB. The UK’s covid-19 data collection has been “world beating”—let’s not throw it away. BMJ 2022; 376 :o496.