Outbreaks of publications about emerging infectious diseases: the case of SARS-CoV-2 and Zika virus

Abstract

Background Outbreaks of infectious diseases generate outbreaks of scientific evidence. In 2016 epidemics of Zika virus emerged, and in 2020, a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a pandemic of coronavirus disease 2019 (COVID-19). We compared patterns of scientific publications for the two infections to analyse the evolution of the evidence. Methods We annotated publications on Zika virus and SARS-CoV-2 that we collected using living evidence databases according to study design. We used descriptive statistics to categorise and compare study designs over time. Results We found 2286 publications about Zika virus in 2016 and 21,990 about SARS-CoV-2 up to 24 May 2020, of which we analysed a random sample of 5294 (24%). For both infections, there were more epidemiological than laboratory science studies. Amongst epidemiological studies for both infections, case reports, case series and cross-sectional studies emerged first, cohort and case-control studies were published later. Trials were the last to emerge. The number of preprints was much higher for SARS-CoV-2 than for Zika virus. Conclusions Similarities in the overall pattern of publications might be generalizable, whereas differences are compatible with differences in the characteristics of a disease. Understanding how evidence accumulates during disease outbreaks helps us understand which types of public health questions we can answer and when.

Occurrence and transmission potential of asymptomatic and presymptomatic SARS-CoV-2 infections: Update of a living systematic review and meta-analysis

“…This covers the period when vaccines started to be rolled out and the alpha variant of concern became dominant in high-income countries. Although we made extensive efforts to comply with the planned 3 monthly updates, with weekly searches and a continuous process of screening, data extraction and risk of bias assessment, the pace of publications about SARS-CoV-2 exceeds the capacity of our crowd of reviewers [ 10 , 26 ]. Our decision to include preprints compensates for some of the delay because these articles appear sooner than peer-reviewed publications.…”

“…Since late 2020, vaccines have become available [ 8 ] and several SARS-CoV-2 variants of concern have spread internationally, with varying viral characteristics [ 9 ]. The number of published studies about SARS-CoV-2 is increasing continuously, and the types of published studies are also changing [ 10 ], including the designs of studies about asymptomatic infection. In systematic reviews of studies published to April 2021, reported point estimates from random effects meta-analysis models range from 17% to 41% [ 11 – 16 ].…”

Occurrence and transmission potential of asymptomatic and presymptomatic SARS-CoV-2 infections: update of a living systematic review and meta-analysis

“…A limitation of the methods for this living systematic review is that this update only includes published studies up to 2 February 2021. Although we made extensive efforts to comply with the planned 3-monthly updates, with weekly searches and a continuous process of screening, data extraction and risk of bias assessment, the pace of publications about SARS-CoV-2 exceeds the capacity of our crowd of reviewers [8, 20]. In reviews of observational epidemiological studies, search terms are broad so the number of studies that needs to be screened is high, but the yield of included studies is low.…”

“…Since late 2020, vaccines have become available [8] and several SARS-CoV-2 variants of concern have spread internationally, with varying viral characteristics [9]. The number of published studies about SARS-CoV-2 is also increasing continuously and the types of published studies are also changing [10], including the designs of studies about asymptomatic infection. In systematic reviews of studies published to April 2021, reported point estimates from random effects meta-analysis models range from 17 to 41% [11][12][13][14][15][16].…”

“…Recognition of asymptomatic and presymptomatic infections has shown the importance of control measures such as physical distancing, active case-finding through testing of asymptomatic people [6] and the need for rapid quarantine [7]. The number of published studies about SARS-CoV-2 is increasing continuously and the types of published studies are also changing [8], including the designs of studies that report on the proportion of people with asymptomatic infection. In systematic reviews, reported estimates from random effects meta-analysis models range from 17 to 41% [9–14].…”