Assessing Covid-19 vaccine effectiveness and safety in England - AstraZeneca

What was the health issue?

Vaccines played an enormous role in reducing the impact of the COVID-19 pandemic, saving an estimated 100,000 lives in the UK. Before being made available to the public, the Oxford/AstraZeneca vaccine had been shown to be safe in clinical trials. However, even once the vaccine was offered to the general public, it was important to continue to understand how effective the vaccine was in the wider population and whether it had any side effects. Understanding how well vaccines work is important to inform decision making about who should receive the vaccine, how many doses they should receive to protect them from getting seriously ill from COVID-19, and for guiding future vaccine development.

What were the researchers trying to find out?

Researchers from AstraZeneca, in partnership with the University of Oxford, wanted to evaluate how safe and effective the Oxford/AstraZeneca COVID-19 vaccine was in the general population by comparing the health outcomes of people who had received the vaccine with people who had not received the vaccine.

Why did the research require the use of health data?

The only way to carry out this research at a population scale was to use anonymised patient health records. Without access to this data, the study would not have been able to evaluate how effective the Oxford/AstraZeneca COVID-19 vaccine was for people across England, regardless of age, ethnicity or health circumstances.

How was the research done?

The patient health records used included anonymised GP records, vaccination history and hospital admissions reports for approximately 47 million people aged 16 and older, registered with GP practices in England. The data were sourced from the NHS COVID-19 Data Store. The data were accessed and analysed through a secure portal called the NHS Digital Trusted Research Environment (TRE). To protect patient privacy, only the specific data required for analysis was used, ensuring data collected was minimised, and all the data was anonymised to remove identifiable information. Vaccinated individuals were matched 1:1 with unvaccinated individuals based on age, gender, and existing health conditions.

What did the research find?

The results of the study confirmed that the vaccine was effective against severe COVID-19 outcomes including hospitalisation, intensive care unit admission and death. Individuals who had received a single vaccine dose had a lower risk of severe COVID-19 outcomes while individuals with two doses had a much lower risk.

Why do the results matter?

Using anonymised patient data, safeguarded by strict privacy measures within the NHS Digital TRE, AstraZeneca found out how effective their vaccine is and how safe it is for the wider population. These results will help AstraZeneca, the Government and the NHS to make important decisions relating to vaccine development and programmes, helping patients to get the best access to preventative vaccines.

Further information

This case study has been adapted from the clinical study: Real World Evaluation of COVID-19 vaccines in England – a post-authorisation effectiveness (PAES) and safety (PASS) study programme utilising population level data from the NHS Digital Trusted Research Environment. 

Glossary

Anonymised data: data where personal information has been removed so that individuals cannot be identified. This process ensures privacy and confidentiality, making it safe to use the data for research or analysis without revealing who the data belongs to.

Hospital Episode Statistics (HES): Hospital data which includes details on patient hospital admissions, outpatient appointments, and accident and emergency attendances at NHS hospitals in England.

NHS Digital Trusted Research Environment (TRE): secure digital platform where approved researchers can use health data without seeing personal details. This helps them study important health questions while keeping everyone's information private and protected.

Post-authorisation effectiveness study (PAES): evaluates the ongoing effectiveness of a medicine after it has been approved.

Post-authorisations safety study (PASS): assesses the safety and risk management of the medicine after it has been approved.