Transmission characteristics of MERS and SARS in the healthcare setting: a comparative study

Abstract

BackgroundThe Middle East respiratory syndrome (MERS) coronavirus has caused recurrent outbreaks in the Arabian Peninsula since 2012. Although MERS has low overall human-to-human transmission potential, there is occasional amplification in the healthcare setting, a pattern reminiscent of the dynamics of the severe acute respiratory syndrome (SARS) outbreaks in 2003. Here we provide a head-to-head comparison of exposure patterns and transmission dynamics of large hospital clusters of MERS and SARS, including the most recent South Korean outbreak of MERS in 2015.MethodsTo assess the unexpected nature of the recent South Korean nosocomial outbreak of MERS and estimate the probability of future large hospital clusters, we compared exposure and transmission patterns for previously reported hospital clusters of MERS and SARS, based on individual-level data and transmission tree information. We carried out simulations of nosocomial outbreaks of MERS and SARS using branching process models rooted in transmission tree data, and inferred the probability and characteristics of large outbreaks.ResultsA significant fraction of MERS cases were linked to the healthcare setting, ranging from 43.5 % for the nosocomial outbreak in Jeddah, Saudi Arabia, in 2014 to 100 % for both the outbreak in Al-Hasa, Saudi Arabia, in 2013 and the outbreak in South Korea in 2015. Both MERS and SARS nosocomial outbreaks are characterized by early nosocomial super-spreading events, with the reproduction number dropping below 1 within three to five disease generations. There was a systematic difference in the exposure patterns of MERS and SARS: a majority of MERS cases occurred among patients who sought care in the same facilities as the index case, whereas there was a greater concentration of SARS cases among healthcare workers throughout the outbreak. Exposure patterns differed slightly by disease generation, however, especially for SARS. Moreover, the distributions of secondary cases per single primary case varied highly across individual hospital outbreaks (Kruskal–Wallis test; P < 0.0001), with significantly higher transmission heterogeneity in the distribution of secondary cases for MERS than SARS. Simulations indicate a 2-fold higher probability of occurrence of large outbreaks (>100 cases) for SARS than MERS (2 % versus 1 %); however, owing to higher transmission heterogeneity, the largest outbreaks of MERS are characterized by sharper incidence peaks. The probability of occurrence of MERS outbreaks larger than the South Korean cluster (n = 186) is of the order of 1 %.ConclusionsOur study suggests that the South Korean outbreak followed a similar progression to previously described hospital clusters involving coronaviruses, with early super-spreading events generating a disproportionately large number of secondary infections, and the transmission potential diminishing greatly in subsequent generations. Differences in relative exposure patterns and transmission heterogeneity of MERS and SARS could point to changes in hospital practices since ...

Real-time monitoring the transmission potential of COVID-19 in Singapore, February 2020

“…In China, substantial hospital-based transmission of SARS-CoV-2 has been reported, with a total of 1700 cases involving among healthcare workers (14,15). This pattern aligns well with past outbreaks of SARS and MERS (16), including substantial nosocomial . CC-BY-NC 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.…”

Estimating and modelling the transmissibility of Middle East Respiratory Syndrome CoronaVirus during the 2015 outbreak in the Republic of Korea

“…Our dynamics model is simplified in many aspects, such as ignoring the age variation in transmissibility and superspreaders . Although transmission was only taken place in hospitals, our model assumes the transmission occurs in the wide population and therefore ignores the setting‐dependent transmission.…”

“…Here, it is worth discussing the target population of transmission dynamics of MERS‐CoV infection in the ROK. All cases in the outbreak, including healthcare workers, patients and visitors, were linked to healthcare settings; it is thus appropriate to assume that the transmission only acts on the people in the healthcare facilities as did in Lee et al . However, it should be noticed that the people in the ROK can freely visit any hospitals they want and relatives and friends have the tradition to visit the patients in hospitals .…”

Clinical and Epidemiologic Characteristics of Spreaders of Middle East Respiratory Syndrome Coronavirus during the 2015 Outbreak in Korea

“…Of MERS-CoV cases, 44%–100% of individual outbreaks were linked to hospitals (56) and a nosocomial outbreak of MERS-CoV may result in a large cluster of cases, the so called “super-spreading events (67). ” However, it is not known whether the spreading events are attributable to host factors such as clinical manifestations or epidemiologic factors such as duration of the nonisolated period (8).…”