| Title:
|
SARS-CoV-2 infection risk during delivery of childhood vaccination campaigns: a modelling study |
| Abstract:
|
BACKGROUND: The COVID-19 pandemic has disrupted delivery of immunisation services globally. Many countries have postponed vaccination campaigns out of concern about infection risks to staff delivering vaccination the children being vaccinated and their families. The World Health Organization recommends considering both the benefit of preventive campaigns and the risk of SARS-CoV-2 transmission when making decisions about campaigns during COVID-19 outbreaks but there has been little quantification of the risks. METHODS: We modelled excess SARS-CoV-2 infection risk to vaccinators vaccinees and their caregivers resulting from vaccination campaigns delivered during a COVID-19 epidemic. Our model used population age-structure and contact patterns from three exemplar countries (Burkina Faso Ethiopia and Chile). It combined an existing compartmental transmission model of an underlying COVID-19 epidemic with a Reed-Frost model of SARS-CoV-2 infection risk to vaccinators and vaccinees. We explored how excess risk depends on key parameters governing SARS-CoV-2 transmissibility and aspects of campaign delivery such as campaign duration number of vaccinations and effectiveness of personal protective equipment (PPE) and symptomatic screening. RESULTS: Infection risks differ considerably depending on the circumstances in which vaccination campaigns are conducted. A campaign conducted at the peak of a SARS-CoV-2 epidemic with high prevalence and without special infection mitigation measures could increase absolute infection risk by 32% to 58% for vaccinators and 0.3% to 0.9% for vaccinees and caregivers. However these risks could be reduced to 3.6% to 8.0% and 0.1% to 0.4% respectively by use of PPE that reduces transmission by 90% (as might be achieved with N95 respirators or high-quality surgical masks) and symptomatic screening. CONCLUSIONS: SARS-CoV-2 infection risks to vaccinators vaccinees and caregivers during vaccination campaigns can be greatly reduced by adequate PPE symptomatic screening and appropriate campaign timing. Our results support the use of adequate risk mitigation measures for vaccination campaigns held during SARS-CoV-2 epidemics rather than cancelling them entirely. |
| Published:
|
2021-05-19 |
| Journal:
|
medRxiv |
| DOI:
|
10.1101/2021.05.14.21257215 |
| DOI_URL:
|
http://doi.org/10.1101/2021.05.14.21257215 |
| Author Name:
|
Procter Simon R |
| Author link:
|
https://covid19-data.nist.gov/pid/rest/local/author/procter_simon_r |
| Author Name:
|
Abbas Kaja |
| Author link:
|
https://covid19-data.nist.gov/pid/rest/local/author/abbas_kaja |
| Author Name:
|
Flasche Stefan |
| Author link:
|
https://covid19-data.nist.gov/pid/rest/local/author/flasche_stefan |
| Author Name:
|
Griffiths Ulla |
| Author link:
|
https://covid19-data.nist.gov/pid/rest/local/author/griffiths_ulla |
| Author Name:
|
Hagedorn Brittany |
| Author link:
|
https://covid19-data.nist.gov/pid/rest/local/author/hagedorn_brittany |
| Author Name:
|
OReilly Kathleen M |
| Author link:
|
https://covid19-data.nist.gov/pid/rest/local/author/oreilly_kathleen_m |
| Author Name:
|
Jit Mark |
| Author link:
|
https://covid19-data.nist.gov/pid/rest/local/author/jit_mark |
| sha:
|
7961df23564826ad4f47969ad789c9182374ccf7 |
| license:
|
cc-by |
| license_url:
|
https://creativecommons.org/licenses/by/4.0/ |
| source_x:
|
MedRxiv; Medline; PMC; WHO |
| source_x_url:
|
https://www.medline.com/https://www.ncbi.nlm.nih.gov/pubmed/https://www.who.int/ |
| pubmed_id:
|
34031666 |
| pubmed_id_url:
|
https://www.ncbi.nlm.nih.gov/pubmed/34031666 |
| pmcid:
|
PMC8142667 |
| pmcid_url:
|
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8142667 |
| url:
|
https://www.ncbi.nlm.nih.gov/pubmed/34031666/
https://doi.org/10.1101/2021.05.14.21257215
http://medrxiv.org/cgi/content/short/2021.05.14.21257215v1?rss=1 |
| has_full_text:
|
TRUE |
| Keywords Extracted from Text Content:
|
COVID-19
Burkina Faso
Reed-Frost
PPE
vaccinators
vaccinees
SARS-CoV-2
children
fixed-post
PPE
vaccine recipients
https://doi.org/10.1101/2021.05.14.21257215 doi
SARS-CoV-2 transmission 14,26,27
Coronavirus Disease 2019
COVID-19 vaccines
people
out-of-home contacts
recipients
foot
Lao PDR
vitamin A
medRxiv preprint Table 1
polio
house-tohouse campaigns 2
medRxiv
COVID-19 pandemic 11
Ecuador
Reed-Frost
Supplementary Figure 5A
Prem
COVID-19 3
contacts
medRxiv preprint
dashed lines
Burkina Faso
vaccinators
Pan American Health Organisation (PAHO
Ukraine
vaccinees
COVID-19 patients
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CovidM
Line colour
individuals
vaccinee
COVID-19
patient
non-household
coronavirus 2
measles campaign
medRxiv preprint 90
Supplementary Figure 3
SARS-CoV-2
DRC
LMICs
children
measles
Graça Matsinhe
Alexei
https://github.com/mert0248/vax_campaign_risk
Rahi
Bill
KMO
Landry Kaucley
Alaa
KA
SRP
SF |
| Extracted Text Content in Record:
|
First 5000 Characters:The COVID-19 pandemic has disrupted delivery of immunisation services globally. Many countries have postponed vaccination campaigns out of concern about infection risks to staff delivering vaccination, the children being vaccinated and their families. The World Health Organization recommends considering both the benefit of preventive campaigns and the risk of SARS-CoV-2 transmission when making decisions about campaigns during COVID-19 outbreaks, but there has been little quantification of the risks.
We modelled excess SARS-CoV-2 infection risk to vaccinators, vaccinees and their caregivers resulting from vaccination campaigns delivered during a COVID-19 epidemic. Our model used population age-structure and contact patterns from three exemplar countries (Burkina Faso, Ethiopia, and Chile). It combined an existing compartmental transmission model of an underlying COVID-19 epidemic with a Reed-Frost model of SARS-CoV-2 infection risk to vaccinators and vaccinees. We explored how excess risk depends on key parameters governing SARS-CoV-2 transmissibility, and aspects of campaign delivery such as campaign duration, number of vaccinations, and effectiveness of personal protective equipment (PPE) and symptomatic screening.
Infection risks differ considerably depending on the circumstances in which vaccination campaigns are conducted. A campaign conducted at the peak of a SARS-CoV-2 epidemic with high prevalence and without special infection mitigation measures could increase absolute infection risk by 32% to 58% for vaccinators, and 0.3% to 0.9% for vaccinees and caregivers. However, these risks could be reduced to 3.6% to 8.0% and 0.1% to 0.4% respectively by use of PPE that reduces transmission by 90% (as might be achieved with N95 respirators or highquality surgical masks) and symptomatic screening.
SARS-CoV-2 infection risks to vaccinators, vaccinees and caregivers during vaccination campaigns can be greatly reduced by adequate PPE, symptomatic screening, and appropriate campaign timing. Our results support the use of adequate risk mitigation measures for vaccination campaigns held during SARS-CoV-2 epidemics, rather than cancelling them entirely.
The Coronavirus Disease 2019 pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has severely disrupted healthcare service delivery globally. In a pulse survey of key informants between May and July 2020, respondents from 90% of the surveyed countries reported disruptions to essential health services, with the greatest disruptions reported in low-and middle-income countries (LMICs) 1 . The same survey reported that one of the most severely disrupted services has been delivery of both outreach and facility-based immunisation.
One major reason for the disruption has been concern around the potential for SARS-CoV-2 transmission during provision of immunisation, particularly through delivery of vaccination campaigns 2 . There is particular concern over putting vaccination staff at increased risk of COVID-19, since healthcare workers are already at high risk of COVID-19 3 , and healthcare workforce pressures are particularly acute due to the need to care for COVID-19 patients.
In March 2020, at the start of the COVID-19 pandemic, the World Health Organization (WHO) and Pan American Health Organisation (PAHO) recommended temporary suspension of preventative immunisation campaigns but encouraged continuation of routine immunisation 2, 4 . In November 2020, with the first COVID-19 wave abating in many LMICs, WHO issued more nuanced recommendations encouraging countries to evaluate decisions around vaccine campaigns by considering both the risk of disease from missed vaccine doses, and the risk of SARS-CoV-2 transmission during campaigns 5 . Some countries (e.g. Ethiopia, DRC and Somalia) that had previously cancelled and postponed vaccine campaigns had reinstated them by September 2020 [6] [7] [8] . For polio eradication, vaccination campaigns were cancelled amid a separate, ongoing public health emergency 9 .
However, quantitative evidence about SARS-CoV-2 infection risk during vaccination campaigns is limited, and urgently needed as many countries face new COVID-19 waves in 2021. Previous modelling studies have demonstrated that the benefits of continuing routine immunisation likely outweigh the excess risk from COVID-19 but did not examine campaign delivery 10 . A recent study has examined risks of vaccine-preventable disease outbreaks (measles, meningococcal A, and Yellow Fever) associated with delaying immunisation campaigns, which varied across countries 11 . Another study assessed the risk of measles outbreaks in Kenya and found that although COVID-19 interventions also temporarily reduced the risk of an outbreak from measles immunity gaps, this risk rises rapidly once these restrictions are lifted highlighting the need to implement catch-up campaigns 12 . One study looked at the risk of transmission in the community during fixed-pos |
| Keywords Extracted from PMC Text:
|
20206–8
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location13
vitamin A
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d≤de+drpt+d′+σ⋅(Pt
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Pan American Health Organisation (PAHO
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Supplementary Figure 5A
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v
d′⋅st+d
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Prem
campaigns12
COVID-19 pandemic11
polio |
| Extracted PMC Text Content in Record:
|
First 5000 Characters:The Coronavirus Disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has severely disrupted healthcare service delivery globally. In a pulse survey of key informants between May and July 2020, respondents from 90% of the surveyed countries reported disruptions to essential health services, with the greatest disruptions reported in low- and middle-income countries (LMICs)1. The same survey reported that one of the most severely disrupted services has been delivery of both outreach and facility-based immunisation.
One major reason for the disruption has been concern around the potential for SARS-CoV-2 transmission during provision of immunisation, particularly through delivery of vaccination campaigns2. There is particular concern over putting vaccination staff at increased risk of COVID-19, since healthcare workers are already at high risk of COVID-193, and healthcare workforce pressures are particularly acute due to the need to care for COVID-19 patients.
In March 2020, at the start of the COVID-19 pandemic, the World Health Organization (WHO) and Pan American Health Organisation (PAHO) recommended temporary suspension of preventative immunisation campaigns but encouraged continuation of routine immunisation2,4. In November 2020, with the first COVID-19 wave abating in many LMICs, WHO issued more nuanced recommendations encouraging countries to evaluate decisions around vaccine campaigns by considering both the risk of disease from missed vaccine doses, and the risk of SARS-CoV-2 transmission during campaigns5. Some countries (e.g. Ethiopia, DRC and Somalia) that had previously cancelled and postponed vaccine campaigns had reinstated them by September 20206–8. For polio eradication, vaccination campaigns were cancelled amid a separate, ongoing public health emergency9.
However, quantitative evidence about SARS-CoV-2 infection risk during vaccination campaigns is limited, and urgently needed as many countries face new COVID-19 waves in 2021. Previous modelling studies have demonstrated that the benefits of continuing routine immunisation likely outweigh the excess risk from COVID-19 but did not examine campaign delivery10. A recent study has examined risks of vaccine-preventable disease outbreaks (measles, meningococcal A, and Yellow Fever) associated with delaying immunisation campaigns, which varied across countries11. Another study assessed the risk of measles outbreaks in Kenya and found that although COVID-19 interventions also temporarily reduced the risk of an outbreak from measles immunity gaps, this risk rises rapidly once these restrictions are lifted highlighting the need to implement catch-up campaigns12. One study looked at the risk of transmission in the community during fixed-post or house-to-house immunisation campaigns in six countries (Angola, Ecuador, Pakistan, Ukraine, Nepal and Lao PDR), but did not model specific interactions between vaccination staff and service users13.
To address this evidence gap, this study models the additional risk of SARS-CoV-2 infection to children receiving vaccination (hereinafter vaccinees), their accompanying caregivers, and vaccinators delivering either fixed-post or house-to-house vaccination campaigns during a simulated COVID-19 epidemic. Our analysis uses demographics from three exemplar countries (Burkina Faso, Ethiopia, and Chile), and explores which factors are most important in determining the magnitude of these infection risks.
We performed deterministic simulations of the SARS-CoV-2 epidemic using CovidM, which uses an age-stratified compartmental SEIR structure (Susceptible, Exposed, Infected - with sub-compartments for asymptomatic, pre-symptomatic and symptomatic infection - and Recovered) and has been described in detail by Davies et al.14 We use the same values as Davies et al. for epidemiological parameters including the latent period, and duration of sub-clinical, pre-clinical, and clinical infectiousness. We also make the same assumptions about the probability of developing clinical symptoms among different age groups15. Our simulations assumed no waning of natural immunity.
To explore the potential impact of population age-structure and social contact patterns on our results we parameterised our model using data for three exemplar countries: Burkina Faso, Ethiopia, and Chile (Supplementary Figures 1 and 2). We used population data from the United Nations population estimates16, and for social contact patterns utilised country- and age-specific synthetic contact matrices reported by Prem et al17. These countries were chosen based on having respectively the lowest, median, and highest population median age amongst countries with a measles vaccination campaign planned for 202018 (but excluding countries for which social contact matrices were unavailable). Our objective was not to predict the actual SARS-CoV-2 epidemics experienced by these particular countries, but rather to generate p |
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