Abstract
Objectives In January 2020, the United Kingdom (UK) removed one of the two infant doses of the 13-valent pneumococcal conjugate vaccine (PCV13), leaving a single priming dose at 3 months and a 12 month booster. We modelled the potential impact on invasive pneumococcal disease (IPD) of a drop in PCV13 coverage associated with the restrictions on non-essential health care visits introduced to combat COVID-19 in the UK on 23 March 2020.
Design Using a previously published model of pneumococcal transmission in England and Wales we simulated the impact of reducing PCV13 coverage by 50% for 3 months from 23 March without subsequent catch-up vaccination. To implement social distancing, we reduced mixing between and within age-groups by either 10% or 50%. In a sensitivity analysis we explored the effect of complete cessation of PCV13 vaccination during the “lockdown” and of extending its duration to 6 months.
Main outcome measures Annual numbers of IPD cases predicted by the model under different vaccination and “lockdown” scenarios with uncertainty intervals (UI) generated from the minimum and maximum values of the model predictions using 500 parameter sets with values within a pre-specified range of the maximum likelihood set.
Results The model predicted that any increase in IPD cases from a reduction in PCV13 coverage would be more than offset by a reduction in pneumococcal transmission due to social distancing, with a net reduction in cumulative IPD cases (UI –1,479, –1,061, all ages) over the next five years. Similar results were obtained in the sensitivity analysis, though with a greater reduction with a 6 month “lockdown”.
Conclusion COVID-19 social distancing measures are predicted to have had a profound effect on pneumococcal transmission resulting in a reduction in pneumococcal carriage prevalence and IPD incidence over the first two years after the “lockdown”. Carriage studies will be informative in confirming the predicted impact of the social distancing measures after they have been lifted.
Competing Interest Statement
The authors have declared no competing interest.
Funding Statement
No external funding was received for this study.
Author Declarations
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Data Availability
The data used for this study are available on the previous published paper on https://journals.plos.org/plosmedicine/article?id=10.1371/journal.pmed.1002845.