Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2023 May;11(5):e759-e769.
doi: 10.1016/S2214-109X(23)00117-1.

Impact of proactive and reactive vaccination strategies for health-care workers against MERS-CoV: a mathematical modelling study

Daniel J Laydon  1 , Simon Cauchemez  2 , Wes R Hinsley  3 , Samir Bhatt  4 , Neil M Ferguson  3
Affiliations

Impact of proactive and reactive vaccination strategies for health-care workers against MERS-CoV: a mathematical modelling study

Daniel J Laydon et al. Lancet Glob Health. 2023 May.

Abstract

Background: Several vaccine candidates are in development against MERS-CoV, which remains a major public health concern. In anticipation of available MERS-CoV vaccines, we examine strategies for their optimal deployment among health-care workers.

Methods: Using data from the 2013-14 Saudi Arabia epidemic, we use a counterfactual analysis on inferred transmission trees (who-infected-whom analysis) to assess the potential impact of vaccination campaigns targeting health-care workers, as quantified by the proportion of cases or deaths averted. We investigate the conditions under which proactive campaigns (ie vaccinating in anticipation of the next outbreak) would outperform reactive campaigns (ie vaccinating in response to an unfolding outbreak), considering vaccine efficacy, duration of vaccine protection, effectiveness of animal reservoir control measures, wait (time between vaccination and next outbreak, for proactive campaigns), reaction time (for reactive campaigns), and spatial level (hospital, regional, or national, for reactive campaigns). We also examine the relative efficiency (cases averted per thousand doses) of different strategies.

Findings: The spatial scale of reactive campaigns is crucial. Proactive campaigns outperform campaigns that vaccinate health-care workers in response to outbreaks at their hospital, unless vaccine efficacy has waned significantly. However, reactive campaigns at the regional or national levels consistently outperform proactive campaigns, regardless of vaccine efficacy. When considering the number of cases averted per vaccine dose administered, the rank order is reversed: hospital-level reactive campaigns are most efficient, followed by regional-level reactive campaigns, with national-level and proactive campaigns being least efficient. If the number of cases required to trigger reactive vaccination increases, the performance of hospital-level campaigns is greatly reduced; the impact of regional-level campaigns is variable, but that of national-level campaigns is preserved unless triggers have high thresholds.

Interpretation: Substantial reduction of MERS-CoV morbidity and mortality is possible when vaccinating only health-care workers, underlining the need for countries at risk of outbreaks to stockpile vaccines when available.

Funding: UK Medical Research Council, UK National Institute for Health Research, UK Research and Innovation, UK Academy of Medical Sciences, The Novo Nordisk Foundation, The Schmidt Foundation, and Investissement d'Avenir France.

PubMed Disclaimer

Conflict of interest statement

Declaration of interests DJL, WRH, SB, and NMF report grants from the UK Medical Research Council (MRC) and the Department for International Development. DJL, SB, and NMF report grants from the UK National Institute for Health and Care Research (NIHR). SC reports grant funding from the Investissement d'Avenir programme, Laboratoire d'Excellence Integrative Biology of Emerging Infectious Diseases programme, and INCEPTION project, outside of the submitted work. SB reports grant funding from Novo Nordisk Foundation, the Danish National Research Foundation, and The Eric & Wendy Schmidt Fund for Strategic Innovation, outside of the submitted work. NMF reports grants from UK Research and Innovation; Community Jameel; Gavi, the Vaccine Alliance; Janssen Pharmaceuticals; and the Bill & Melinda Gates Foundation, outside of the submitted work. Additionally, NMF reports consulting fees for the World Bank Group (ceased in 2019); payment for sitting on a grant panel and an advisory board for the Wellcome Trust; travel expenses for WHO meetings; and sitting on an advisory board for Takeda in relation to their dengue vaccine, for which no honoraria, gifts, or expenses of any kind were received. NMF is a senior editor for the journal eLife. All other authors declare no competing interests.

Figures

Figure 1
Figure 1
MERS-CoV incidence and inferred transmission trees for the 2013–14 outbreak in Saudi Arabia (A–B) Weekly incidence of MERS-CoV cases (A) and deaths (B) among health-care workers and overall. (C–F) Inferred transmission trees. Each tree is a posterior sample of the infectors of each case, including the animal reservoir, for a particular modelled scenario. Examples are shown for the following scenarios: no vaccination (C); a reactive campaign at the regional level with a 60% efficacious vaccine, 20-year mean duration of protection, and 14-day reaction time (D); a proactive campaign with a 60% efficacious vaccine, 20-year mean duration of protection, and 6-month wait before the next outbreak (E); and considering only control measures targeting transmission from the animal reservoir, with 50% effectiveness (F).
Figure 2
Figure 2
Effect of proactive vaccination campaign on cases Plots show the mean posterior estimates of the proportion of cases averted, by vaccine efficacy, mean duration of vaccine protection (assuming exponential waning), wait until next outbreak, and reservoir control measure effectiveness.
Figure 3
Figure 3
Effect of reactive vaccination campaign on cases Plots show the mean posterior estimates of the proportion of cases averted, by vaccine efficacy, mean duration of vaccine protection (assuming exponential waning), reaction time, and spatial level.
Figure 4
Figure 4
Comparison of proactive and reactive strategies Plots show the ratio of cases averted with proactive campaigns versus reactive campaigns (proactive divided by reactive), with varying values of duration of vaccine protection and wait between vaccination and next outbreak. Proactive campaigns are compared with reactive campaigns at the hospital, regional, and national levels. A 28-day reaction time and a 14-day lag between vaccination and immunity are assumed in all plots. Ratios less than 1 (left of black contour line) indicate that a reactive campaign averts more cases than a proactive campaign.
See this image and copyright information in PMC

Comment in

References

    1. Park J-E, Jung S, Kim A, Park J-E. MERS transmission and risk factors: a systematic review. BMC Public Health. 2018;18:574. - PMC - PubMed
    1. WHO MERS situation update. August 2022. https://applications.emro.who.int/docs/WHOEMCSR552E-eng.pdf?ua=1
    1. Lessler J, Salje H, Van Kerkhove MD, et al. Estimating the severity and subclinical burden of Middle East respiratory syndrome coronavirus infection in the Kingdom of Saudi Arabia. Am J Epidemiol. 2016;183:657–663. - PMC - PubMed
    1. Cauchemez S, Van Kerkhove MD, Riley S, Donnelly CA, Fraser C, Ferguson NM. Transmission scenarios for Middle East respiratory syndrome coronavirus (MERS-CoV) and how to tell them apart. Euro Surveill. 2013;18 - PMC - PubMed
    1. Cauchemez S, Nouvellet P, Cori A, et al. Unraveling the drivers of MERS-CoV transmission. Proc Natl Acad Sci USA. 2016;113:9081–9086. - PMC - PubMed

Publication types

MeSH terms