Estimation of the serial interval and proportion of pre-symptomatic transmission events of COVID-19 in Ireland using contact tracing data

Title: Estimation of the serial interval and proportion of pre-symptomatic transmission events of COVID-19 in Ireland using contact tracing data
Authors: McAloon, Conor G.Wall, Patrick G.Griffin, John M.Casey, MiriamBarber, AnnCodd, MaryGormley, EamonnButler, FrancisMessam, Locksley L. McV.O'Grady, LukeMore, Simon Johnet al.
Permanent link: http://hdl.handle.net/10197/12161
Date: 27-Apr-2021
Online since: 2021-05-17T15:58:44Z
Abstract: The serial interval is the period of time between the onset of symptoms in an infector and an infectee and is an important parameter which can impact on the estimation of the reproduction number. Whilst several parameters influencing infection transmission are expected to be consistent across populations, the serial interval can vary across and within populations over time. Therefore, local estimates are preferable for use in epidemiological models developed at a regional level. We used data collected as part of the national contact tracing process in Ireland to estimate the serial interval of SARS-CoV-2 infection in the Irish population, and to estimate the proportion of transmission events that occurred prior to the onset of symptoms. Results After data cleaning, the final dataset consisted of 471 infected close contacts from 471 primary cases. The median serial interval was 4 days, mean serial interval was 4.0 (95% confidence intervals 3.7, 4.3) days, whilst the 25th and 75th percentiles were 2 and 6 days respectively. We found that intervals were lower when the primary or secondary case were in the older age cohort (greater than 64 years). Simulating from an incubation period distribution from international literature, we estimated that 67% of transmission events had greater than 50% probability of occurring prior to the onset of symptoms in the infector. Conclusions Whilst our analysis was based on a large sample size, data were collected for the primary purpose of interrupting transmission chains. Similar to other studies estimating the serial interval, our analysis is restricted to transmission pairs where the infector is known with some degree of certainty. Such pairs may represent more intense contacts with infected individuals than might occur in the overall population. It is therefore possible that our analysis is biased towards shorter serial intervals than the overall population.
Type of material: Journal Article
Publisher: BioMed Central
Journal: BMC public health
Volume: 21
Issue: 1
Copyright (published version): 2021 the Authors
Keywords: COVID-19Contact tracingSARS-CoV-2Serial intervalCoronavirus
DOI: 10.1186/s12889-021-10868-9
Language: en
Status of Item: Peer reviewed
ISSN: 1471-2458
This item is made available under a Creative Commons License: https://creativecommons.org/licenses/by/3.0/ie/
Appears in Collections:Biosystems and Food Engineering Research Collection
Public Health, Physiotherapy and Sports Science Research Collection
Veterinary Medicine Research Collection
CVERA Research Collection

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