S29  Search, QA, summarization  CAiRE-Covid [83]  The Centre for Artificial Intelligence Research (CAiRE), HKUST  https://caire.ust.hk/covid/  CORD-19, Biomedical reviews [111]  Keyword-based retrieval of paragraphs using Anserini []. Reranking and answer selection using ensemble of BioBERT QA model [49] and generalized MRQA model [82]. Summarize answers across multiple documents abstractively with BART [51] and UniLM [26], and extractively with nearest neighbor ALBERT [47] sentence embeddings.  Supports user-written natural questions, returns a ranked list of matching articles with highlighted answer spans. Provides extractive and abstractive summary over all answer spans.