COVID-19 hospital admissions and deaths post BNT162b2 and ChAdOx1 vaccinations: National prospective cohort study of 2.57 million people in Scotland

September 2021: New research published in The Lancet Respiratory Medicine looks at the number of people in Scotland who have died from or been admitted to hospital with COVID-19 after at least one vaccine dose.

Summary in Plain English

September 2021: New research published in The Lancet Respiratory Medicine looks at the number of people in Scotland who have died from or been admitted to hospital with COVID-19 after at least one vaccine dose.

The COVID-19 vaccination programme started on 8 December 2020 in Scotland with the Pfizer-BioNTech (BNT162b2) vaccine. Vaccination clinics and GPs started to give the Oxford-AstraZeneca (ChAdOx1) vaccine on 4 January 2021, after it was approved by the Medicines and Healthcare products Regulatory Agency (MHRA).

In Scotland, 2.57 million adults (62% of adult population) were given the first dose of a COVID-19 vaccine between 8 December 2020 and 18 April 2021. Two-thirds of this group had the Oxford Astra-Zeneca vaccine and one-third had the Pfizer-BioNTech vaccine.

Find out more about the role of the MHRA and other committees in approving COVID-19 vaccines

Why did we carry out this study?

Looking carefully at the number and type of people who develop severe COVID-19 even after being vaccinated can provide important information for healthcare decisions, including:

• How to prioritise second vaccine and possibly booster doses
• Updating advice on which people should shield
• Predicting future pressures on the National Health Service.

We wanted to look at how many people in Scotland have been admitted to hospital or died of COVID-19 after at least one vaccine dose, and whether particular groups are at higher risk than others.

Our analysis is the first study on a national scale to do this. We used the EAVE II database to carry out the research.

Find out more about EAVE II

What definitions did we use?

In this summary, a ‘serious COVID-19 event’ includes hospital admissions or deaths due to COVID-19.

We looked at who was admitted to hospital or died because of COVID-19. We started our analysis from 14 days after each person received their first vaccination, to allow for the time needed to build up immune protection after vaccination.

We defined COVID-19 hospital admissions as anyone admitted to hospital within 0-14 days of a positive PCR (‘polymerase chain reaction’) test, or with COVID-19 recorded as the reason they were admitted. We also included anyone admitted to hospital for a non-COVID reason who had a positive PCR test during their time in hospital.

In our definition of COVID-19 deaths, we included all those who died within 28 days of a positive PCR test, or with COVID-19 listed as the main cause of death on their death certificate.

What did we find?

We found that between 8 December 2020 and 18 April 2021, less than one in 2000 vaccinated people in Scotland had a serious COVID-19 event, despite high background levels of infection at the time.

Of the 2.57 million adults given the first dose of their vaccine, 883 people were admitted to hospital with COVID-19. In the same period, 541 people died of COVID-19.

Nearly 700,000 people (27% of those included in the study) had their second vaccine during this time-period. Of these, 39 (0.006%) suffered one of these serious events.

Finally, we found that having had a COVID-19 infection before being vaccinated reduced a person’s risk of serious COVID-19 disease after vaccination. This was the case for both types of vaccine studied.

Which groups are at higher risk of severe COVID-19 even after being vaccinated?

To find any high-risk groups, we included in our analysis: age, sex at birth, COVID-19 and recent hospitalisation history, relevant underlying health conditions, level of deprivation by postcode, smoking status, urban/rural residence, and time since first vaccination.

We looked at risk for the Pfizer-BioNTech and Oxford-AstraZeneca vaccines combined and individually. The following groups were at higher risk of severe COVID-19 even after vaccination, listed in order with the highest first:

1. Being older (over-80s vs 18-64 years)
2. Having multiple underlying health conditions (5+ compared to none)
3. Being admitted to hospital in the previous four weeks
4. Having a high-risk occupation (based on taking 10 or more tests weekly vs none)
5. Being a care home resident
6. Living in a deprived area
7. Being male
8. Being an ex-smoker.

The risks listed above range from roughly five times higher for age, to only slightly higher for ex-smokers compared to non-smokers. All of these conditions, except for smoking history, are also linked to higher risk of severe COVID-19 in unvaccinated people.

Taking into account age, sex and level of social deprivation, we found people with a history of the following conditions were at increased risk of being admitted to hospital or dying due to COVID-19, even after having at least one vaccine:

• Asthma
• Chronic kidney disease
• Heart failure
• Type 2 diabetes
• Dementia
• Coronary heart disease.

Although people in the groups shown above are at higher risk of serious COVID-19 events, the total number of serious events is still low in people who have had two vaccine doses. These data may also help to prioritise people at higher risk for booster vaccines.

What is next?

We plan to continue analysing post-vaccination serious COVID-19 outcomes, particularly following the second vaccine dose. This work is needed as it is important to understand the impact of lockdown restrictions being eased, young people being vaccinated, new vaccines like Moderna and Janssen being introduced, and new variants such as the Delta Variant of Concern (VOC) emerging.

EAVE II is being used to inform how the UK and Scottish Governments and public health agencies respond to the pandemic.

Find out more about EAVE II’s work and publications

Note

This plain English summary and infographic were created with the support and feedback of the EAVE II Public Advisory Group (PAG). This summary in particular was reviewed by Deb S and Joanna C.

To learn more about the PAG, see: Our EAVE II Public Advisory Group (PAG) | The University of Edinburgh