Press Release

Characteristics of SARS-CoV-2 super-spreaders in Japan

January 17, 2022

Abstract

Dear Editor,
In this Journal, Majra and colleagues reviewed the role of `super-spreaders' in the COVID-19 pandemic1. Since the time of the SARS-CoV epidemic in 2003 and the MERS-CoV epidemic in 2012, it was found that not all patients were equally infectious; super-spreaders were highly contagious to their surroundings and could transmit the infection2. Based on the experience of these two epidemics, a super-spreader can be defined as a patient who has a high viral load, sheds virus for a long period of time, and is not necessarily critically ill3. In the Covid-19 pandemic, it has also been noted that high viral load leads to high infectivity4,5, and that the presence of super-spreaders is involved in super-spreading events, where some individuals spread to a disproportionate number of individuals, compared to most individuals who infected only a few or none3,6. It has also been reported that patients with severe disease have higher viral load and longer viral shedding period compared to patients with mild disease7. However, few studies have examined the characteristics of people with high copy number, taking into account the fact that viral load changes over time. To that end, we conducted a single-center, retrospective study in patients diagnosed with COVID-19 and had their PCR copy number measured multiple times (Supplementary materials 1). Between March 2020 and June 2021, patients with a confirmed diagnosis of COVID-19, admitted to Tokyo Medical and Dental University, with polymerase chain reaction (PCR) copy number measured one or more times (median tested times: 2, range 1–26), were included in the study. A total of 379 patients were eligible for the study.

Table 1 shows the demographic data of the patients. The median age of the patients was 59 years, and about 33% were female. Median number of PCR tests was 2 (range: 1–26). In more than 90% of the patients who had more than one PCR test performed, the viral load was its maximum for that individual at the first or second test. About 59% had underlying disease and about 21% had more than three underlying diseases. Underlying diseases included hypertension (146, 38.5%), diabetes mellitus (82, 21.6%), dyslipidemia (70, 18.5%), hyperuricemia (29, 7.7%), rheumatoid arthritis (8, 2.1%), cancer (71, 18.7%), chronic kidney disease (25, 6.6%), stroke (19, 5.0%), heart disease (including myocardial infarction, atrial fibrillation, chronic heart disease, 34, 9.0%), and lung disease (including asthma and chronic obstructive lung disease, 41, 10.8%). All but one patient in this study were unvaccinated.

Journal Article

JOURNALJournal of Infection

TITLE:Characteristics of  SARS-CoV-2 super-spreaders in Japan

DOIhttps://doi.org/10.1016/j.jinf.2021.12.036

Correspondence to

 Takeo Fujiwara,Ph.D.,Professor

Department of Global Health Promotion,
Graduate School of Medical and Dental Sciences,
Tokyo Medical and Dental University, (TMDU)
E-mail:fufujiwara.hlth(at)tmd.ac.jp

*Please change (at) in the e-mail addresses to @ when sending correspondence.