Influenza A (H5N1) infection, characterized by fever, respiratory symptoms, and lymphopenia, carries a high risk of death. Although in all 10 cases the infection appears to have been acquired directly from infected poultry, the potential exists for genetic reassortment with human influenzaviruses and the evolution of human-to-human transmission. Containment of influenza A (H5N1) in poultry throughout Asia is therefore urgently required.

Background Little is known about the natural history of asymptomatic SARS-CoV-2 infection or its contribution to infection transmission. Methods We conducted a prospective study at a quarantine center for COVID-19 in Ho Chi Minh City, Vietnam. We enrolled quarantined people with RT-PCR-confirmed SARS-CoV-2 infection, collecting clinical data, travel and contact history, and saliva at enrolment and daily nasopharyngeal throat swabs (NTS) for RT-PCR testing. We compared the natural history and transmission potential of asymptomatic and symptomatic individuals. Results Between March 10th and April 4th, 2020, 14,000 quarantined people were tested for SARS-CoV-2; 49 were positive. Of these, 30 participated in the study: 13(43%) never had symptoms and 17(57%) were symptomatic. 17(57%) participants acquired their infection outside Vietnam. Compared with symptomatic individuals, asymptomatic people were less likely to have detectable SARS-CoV-2 in NTS samples collected at enrolment (8/13 (62%) vs. 17/17 (100%) P=0.02). SARS-CoV-2 RNA was detected in 20/27 (74%) available saliva; 7/11 (64%) in the asymptomatic and 13/16 (81%) in the symptomatic group (P=0.56). Analysis of the probability of RT-PCR positivity showed asymptomatic participants had faster viral clearance than symptomatic participants (P<0.001 for difference over first 19 days). This difference was most pronounced during the first week of follow-up. Two of the asymptomatic individuals appeared to transmit the infection to up to four contacts. Conclusions Asymptomatic SARS-CoV-2 infection is common and can be detected by analysis of saliva or NTS. NTS viral loads fall faster in asymptomatic individuals, but they appear able to transmit the virus to others.

Use of oral prednisolone for 3 days during the early acute phase of dengue virus infection appears to be safe, but did not reduce the rate of development of shock or other recognized complications of dengue in this randomized, placebo-controlled trial.

248 2 1 Main text: 2788 2 2 Running title: Asymptomatic SARS-CoV-2 infection 2 3 ABSTRACT 2 5 Background 2 6Little is known about the natural history of asymptomatic SARS-CoV-2 infection or its 2 7 contribution to infection transmission. 2 8 Methods 2 9We conducted a prospective study at a quarantine centre for COVID-19 in Ho Chi Minh City, 3 0 Vietnam. We enrolled quarantined people with RT-PCR-confirmed SARS-CoV-2 infection, 3 1 collecting clinical data, travel and contact history, and saliva at enrolment and daily 3 2 nasopharyngeal throat swabs (NTS) for RT-PCR testing. We compared the natural history and 3 3 transmission potential of asymptomatic and symptomatic individuals.3 4 Results 3 5Between March 10 th and April 4 th , 2020, 14,000 quarantined people were tested for SARS-3 6CoV-2; 49 were positive. Of these, 30 participated in the study: 13(43%) never had symptoms 3 7 and 17(57%) were symptomatic. 17(57%) participants acquired their infection outside Vietnam. 3 8 Compared with symptomatic individuals, asymptomatic people were less likely to have 3 9 detectable SARS-CoV-2 in NTS samples collected at enrolment (8/13 (62%) vs. 17/17 (100%) 4 0 P=0.02). SARS-CoV-2 RNA was detected in 20/27 (74%) available saliva; 7/11 (64%) in the 4 1 asymptomatic and 13/16 (81%) in the symptomatic group (P=0.56). Analysis of the probability 4 2 of RT-PCR positivity showed asymptomatic participants had faster viral clearance than 4 3 symptomatic participants (P<0.001 for difference over first 19 days). This difference was most 4 4 pronounced during the first week of follow-up. Two of the asymptomatic individuals appeared 4 5 to transmit the infection to up to four contacts. 4 6 Conclusions 4 7 Asymptomatic SARS-CoV-2 infection is common and can be detected by analysis of saliva or 4 8 NTS. NTS viral loads fall faster in asymptomatic individuals, but they appear able to transmit 4 9 the virus to others. 5 0 Hospitals, located approximately 60 km to the West and East, respectively, of HCMC (Figure 9 7 2A).