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. 2024 Sep;89(3):106221.
doi: 10.1016/j.jinf.2024.106221. Epub 2024 Jul 10.

The impact of COVID-19 vaccine spring boosters on COVID-19 hospital admissions in England 2022/23

Nick Andrews  1 , Itunu Osuntoki  2 , Julia Stowe  1 , Freja C M Kirsebom  3 , Alex Allen  1 , Jamie Lopez Bernal  1
Affiliations
Free article

The impact of COVID-19 vaccine spring boosters on COVID-19 hospital admissions in England 2022/23

Nick Andrews et al. J Infect. 2024 Sep.
Free article

Abstract

Background: In the spring of 2022 and 2023 COVID-19 vaccine boosters were recommended for those aged ≥75 years in England as well as those in an immunosuppression risk group. The aim was to reduce severe COVID-19 disease in these groups.

Methods: The large difference in coverage between those above and below age 75 years was the basis for applying an age-discontinuity approach for measuring the impact of vaccination on COVID-19 hospitalisations in both spring 2022 and 2023. Hospitalisations in individuals positive by PCR for COVID-19 were obtained from the national secondary user service hospital dataset. The ratio of hospital counts by each year of age in 8-week periods after compared to before the roll out was modelled using negative binomial regression to estimate the discontinuity at age 75 years.

Results: A clear discontinuity was seen at age 75 years of 17.0% (95% CI: 6.1%-26.6%) in 2022 and 18.0% (3.3%-30.4%) in 2023. If applied to those aged ≥75 years this translates to 1302 and 418 averted hospitalisations in the 8-week period in 2022 and 2023, respectively.

Conclusions: This study shows a clear impact of vaccination on preventing COVID-19 hospitalisations and compliments other epidemiological methods assessing the impact of COVID-19 vaccines.

Plain language summary: One way to see if the booster vaccines doses given to protect against COVID-19 disease are working is to compare hospital admissions in groups of people who were and were not eligible for the dose. In England the spring booster doses were recommended for those aged 75 years and above. We could therefore compare hospitalisations in those above this age to those just below (aged 65-74) and see if there is a step change in rates from age 74 to 75 in the time after the vaccine was given. The results showed hospitalisations were about 18% lower in the group that were eligible, which is evidence that the vaccine is protecting against severe COVID-19.

Keywords: Age-discontinuity; COVID-19 vaccine; Hospitalisations; Impact; Quasi-experimental.

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Conflict of interest statement

Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: The authors declare no personal conflicts of interest. The Immunisation Department provides vaccine manufacturers (including Pfizer) with post-marketing surveillance reports about pneumococcal and meningococcal disease, which the companies are required to submit to the UK Licensing authority in compliance with their Risk Management Strategy. A cost recovery charge is made for these reports.

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