Characteristics and research collaboration of registered systematic reviews (SRs) on treatment modalities for coronavirus disease-2019 (COVID-19) remain unclear. This study analysed research collaboration, interventions and outcome measures in registered SRs on COVID-19 treatments and pointed out the relevant problems. PROSPERO (international prospective register of systematic reviews) was searched for SRs on COVID-19 treatments as of 2 June 2020. Excel 2016 was used for descriptive analyses of the extracted data. VOSviewer 1.6.14 software was used to generate network maps for collaborations between countries and institutions. A total of 189 SRs were included, which were registered by 301 institutions from 39 countries. China (69, 36.50%) exhibited the highest output. Cooperation between countries was not close enough. As an institution, the Chengdu University of Traditional Chinese Medicine (7, 3.70%) had the highest output. There was close cooperation between institutions. Interventions included antiviral therapy (81, 42.86%), respiratory support (16, 8.47%), circulatory support (11, 5.82%), plasma therapy for convalescent patients (11, 5.82%), immunotherapy (9, 4.76%), TCM (traditional Chinese medicine) treatment (9, 4.76%), rehabilitation treatment (5, 2.65%), anti-inflammatory treatment (16, 8.47%) and other treatments (31, 16.40%). Concerning antiviral therapy (81, 42.86%), the most commonly used antiviral agents were chloroquine/hydroxychloroquine (26, 13.76%), followed by remdesivir (12, 6.35%), lobinavir/ritonavir (11, 5.82%), favipiravir (5, 2.65%), ribavirin (5, 2.65%), interferon (5, 2.65%), abiron (4, 2.12%) and abidor (4, 2.12%). The most frequently used primary and secondary outcomes were the mortality rate (92, 48.68%) and hospital stay length (48, 25.40%), respectively. The expression of the outcomes was not standardised. Many COVID-19 SRs on treatment modalities have been registered, with a low completion rate. Although there was some collaboration between countries and institutions in the currently registered SRs on treatment modalities for COVID-19 on PROSPERO, cooperation between countries should be further enhanced. More attention should be directed towards identifying deficiencies of outcome measures, and the standardisation of results should be maximised.

Microplastic pollution is a global enviromental issues. This is the first time in recent decades that quantitative and qualitative evidence from bibliometrics and Altmetric has been used to conduct an in-depth statistical analysis of global microplastics research knowledge and demonstrate research progress, trends and hotspots. We comprehensively searched the Web of Science Core Collection scientific database from its inception (1986) to September 21, 2019. The study shown that the number of papers on microplastics has increased significantly since 2011. Worldwide, researchers in the field come mostly from Western Europe, mainly spread in the UK, Netherlands and Belgium. With the exception of China, the contribution of developing countries was very limited. Moreover, this study systematically elaborated the hotspots in this field (especially in ecological toxicity and human health risks). The results shown that research on marine systems and marine plankton is still dominant. Since human beings are the ultimate consumers of the food chain, microplastics may have potential effects on the human respiratory system and gastrointestinal tract. Towards that end, some topics and perspectives are noted that could indicate the current scientific hotspots and guide future research directions.