Public health impact of booster vaccination against COVID-19 in the UK during Delta variant dominance in autumn 2021

Abstract

Aim

To evaluate the public health impact of the UK COVID-19 booster vaccination program in autumn 2021, during a period of SARS-CoV-2 Delta variant predominance.

Materials and methods

A compartmental Susceptible-Exposed-Infectious-Recovered model was used to compare age-stratified health outcomes for adult booster vaccination versus no booster vaccination in the UK over a time horizon of September–December 2021, when boosters were introduced in the UK and the SARS-CoV-2 Delta variant was predominant. Model input data were sourced from targeted literature reviews and publicly available data. Outcomes were predicted COVID-19 cases, hospitalizations, post-acute sequelae of COVID-19 (PASC) cases, deaths, and productivity losses averted, and predicted healthcare resources saved. Scenario analyses varied booster coverage, virus infectivity and severity, and time horizon parameters.

Results

Booster vaccination was estimated to have averted approximately 547,000 COVID-19 cases, 36,000 hospitalizations, 147,000 PASC cases, and 4,200 deaths in the UK between September and December 2021. It saved over 316,000 hospital bed-days and prevented the loss of approximately 16.5 million paid and unpaid patient work days. In a scenario of accelerated uptake, the booster rollout would have averted approximately 3,400 additional deaths and 25,500 additional hospitalizations versus the base case. A scenario analysis assuming four-fold greater virus infectivity and lower severity estimated that booster vaccination would have averted over 105,000 deaths and over 41,000 hospitalizations versus the base case. A scenario analysis assuming pediatric primary series vaccination prior to adult booster vaccination estimated that expanding vaccination to children aged ≥5 years would have averted approximately 51,000 additional hospitalizations and 5,400 additional deaths relative to adult booster vaccination only.

Limitations

The model did not include the wider economic burden of COVID-19, hospital capacity constraints, booster implementation costs, or non-pharmaceutical interventions.

Conclusions

Booster vaccination during Delta variant predominance reduced the health burden of SARS-CoV-2 in the UK, releasing substantial NHS capacity.

Keywords:

• COVID-19
• Delta variant
• dynamic transmission model
• public health impact
• SARS-CoV-2
• BNT162b2
• mRNA-1273
• COVID-19 booster vaccination

JEL CLASSIFICATION CODES:

• I10
• I1
• I
• I18
• C52
• C5
• C

Transparency

Declaration of funding

This study was sponsored by Pfizer, Inc.

Declaration of financial/other relationships

DM, JA, JN, LH, MDF, CC, and JY are employees of Pfizer and may own Pfizer stock. RC and PG are employees of Evidera, which received financial support from Pfizer, Inc. in connection with the study and the development of this manuscript. Peer reviewers on this manuscript have received an honorarium from JME for their review work but have no other relevant financial relationships to disclose.

Author contributions

All authors were involved in the conception and design of the study, contributed to data analysis and interpretation, and drafted the manuscript. All authors revised the manuscript critically for intellectual content, approved the final version of the manuscript, and agree to be accountable for all aspects of the work.

Acknowledgements

Medical writing was provided by Jacqueline Janowich Wasserott, Jonathan Pitt, and Stephen Gilliver (Evidera) and was funded by Pfizer, Inc. Input into early model development was provided by Russell Becker, Thomas Scassellati Sforzolini, and Julie Roiz (Evidera) and was funded by Pfizer, Inc. Elena Aruffo (Evidera) provided analytical support and was funded by Pfizer, Inc.

Data availability statement

Data generated or analyzed during this study are available upon request.