Elsevier has created a COVID-19 resource centre with free information in English and Mandarin on the novel coronavirus COVID-19. The COVID-19 resource centre is hosted on Elsevier Connect, the company's public news and information website.Elsevier hereby grants permission to make all its COVID-19-related research that is available on the COVID-19 resource centre -including this research content -immediately available in PubMed Central and other publicly funded repositories, such as the WHO COVID database with rights for unrestricted research re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for free by Elsevier for as long as the COVID-19 resource centre remains active.

Our study demonstrated an extremely high rate of Caesarean section and associated factors in public and private hospitals in one of the biggest cities in Vietnam. The findings highlight the need for monitoring and interventions to reduce the Caesarean section rates.

We systematically searched and meta-analyzed the epidemiological characteristics, frequency of clinical signs, and outcomes of dengue-associated hemophagocytic lymphohistiocytosis. Ten electronic databases were searched systematically plus manual search of reference lists to identify relevant articles published until May 2017. The highest number of reported cases were from South-East Asia region (62 cases), followed by Western Pacific region (20 cases), and America (31 cases). The term "dengue hemorrhagic fever" predominated in studies that used the World Health Organization 1997 definition (59.7%), whereas "severe dengue" predominated in studies using the World Health Organization 2009 definition (76.8%). Among 122 cases, fever, splenomegaly, hepatomegaly, anemia, thrombocytopenia, and serum ferritin ≥500 μg/L were likely to report by articles representing by large sample size. The pooled proportion of these findings were as follows: fever 97.2%, hepatomegaly 70.2%, splenomegaly 78.4%, thrombocytopenia 90.1%, anemia 76.0%, and serum ferritin ≥500 μg/L 97.1%. This study highlighted a high case fatality rate (14.6%) and co-infection among dengue hemophagocytic lymphohistiocytosis patients. We suggest that long fever duration, persistent thrombocytopenia, elevated serum ferritin, and lactate dehydrogenase levels could be good diagnostic indicators for dengue-associated hemophagocytic syndrome. Bone marrow aspiration could be used as one criterion for diagnosis but is not obligatory. Further research is needed to examine the possible risk difference for development of hemophagocytic syndrome and to explore potential relationships between specific dengue classifications and dengue-associated hemophagocytic syndrome.