To assess the role of in-flight transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we investigated a cluster of cases among passengers on a 10-hour commercial flight. Affected persons were passengers, crew, and their close contacts. We traced 217 passengers and crew to their final destinations and interviewed, tested, and quarantined them. Among the 16 persons in whom SARS-CoV-2 infection was detected, 12 (75%) were passengers seated in business class along with the only symptomatic person (attack rate 62%). Seating proximity was strongly associated with increased infection risk (risk ratio 7.3, 95% CI 1.2–46.2). We found no strong evidence supporting alternative transmission scenarios. In-flight transmission that probably originated from 1 symptomatic passenger caused a large cluster of cases during a long flight. Guidelines for preventing SARS-CoV-2 infection among air passengers should consider individual passengers’ risk for infection, the number of passengers traveling, and flight duration.

Background One hundred days after SARS-CoV-2 was first reported in Vietnam on January 23rd, 270 cases were confirmed, with no deaths. We describe the control measures used by the Government and their relationship with imported and domestically-acquired case numbers, with the aim of identifying the measures associated with successful SARS-CoV-2 control. Methods Clinical and demographic data on the first 270 SARS-CoV-2 infected cases and the timing and nature of Government control measures, including numbers of tests and quarantined individuals, were analysed. Apple and Google mobility data provided proxies for population movement. Serial intervals were calculated from 33 infector-infectee pairs and used to estimate the proportion of pre-symptomatic transmission events and time-varying reproduction numbers. Results A national lockdown was implemented between April 1st and 22nd. Around 200 000 people were quarantined and 266 122 RT-PCR tests conducted. Population mobility decreased progressively before lockdown. 60% (163/270) of cases were imported; 43% (89/208) of resolved infections remained asymptomatic for the duration of infection. The serial interval was 3·24 days, and 27·5% (95% confidence interval, 15·7%-40·0%) of transmissions occurred pre-symptomatically. Limited transmission amounted to a maximum reproduction number of 1·15 (95% confidence interval, 0·37-2·36). No community transmission has been detected since April 15th. Conclusions Vietnam has controlled SARS-CoV-2 spread through the early introduction of mass communication, meticulous contact-tracing with strict quarantine, and international travel restrictions. The value of these interventions is supported by the high proportion of asymptomatic and imported cases, and evidence for substantial pre-symptomatic transmission.

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Background:One hundred days after SARS-CoV-2 was first reported in Vietnam on January 23 rd , 270 cases have been confirmed, with no deaths. We describe the control measures used by the Government and their relationship with imported and domestically-acquired case numbers, with the aim of identifying the measures associated with successful SARS-CoV-2 control. Methods:Clinical and demographic data on the first 270 SARS-CoV-2 infected cases and the timing and nature of Government control measures, including numbers of tests and quarantined individuals, were captured by Vietnam's National Steering Committee for COVID-19 response. Apple and Google mobility data provided proxies for population movement. Serial intervals were calculated from 33 infector-infectee pairs and used to estimate the proportion of pre-symptomatic transmission events and time-varying reproduction numbers. Findings:After the first confirmed case on January 23 rd , the Vietnamese Government initiated mass communications measures, case-contact tracing, mandatory 14-day quarantine, school and university closures, and progressive flight restrictions. A national lockdown was implemented between April 1 st and 22 nd . Around 200 000 people were quarantined and 266 122 RT-PCR tests conducted. Population mobility decreased progressively before lockdown. 60% (163/270) of cases were imported; 43% (89/208) of resolved infections remained asymptomatic for the duration of infection. 21 developed severe disease, with no deaths. The serial interval was 3·24 days, and 27·5% (95% confidence interval, 15·7%-40·0%) of transmissions occurred pre-symptomatically. Limited transmission amounted to a maximum reproduction number of 1·15 (95% confidence interval, 0·37-2·36). No community transmission has been detected since April 15 th .

Background The importation of SARS-CoV-2 through air travel poses substantial risks to generate new COVID-19 outbreaks. Timely contact tracing is particularly crucial to limit onwards transmission in settings without established community transmission. Methods We conducted an in-depth analysis of the response to a big flight-associated COVID-19 outbreak in Vietnam in March 2020 that involved contact tracing, systematic testing and strict quarantine up to third generation contacts. Results 183 primary contacts from the flight as well as 1,000 secondary and 311 third generation contacts were traced, tested, and quarantined across 15 provinces across Vietnam. The protracted confirmation of the index case at 3 days and 19 hours after arrival resulted in isolation/quarantine delays of 6.8 days (IQR 6.3–6.8) and 5.8 days (IQR 5.8–7.0) for primary and secondary cases, respectively, which generated 84.0 and 26.4 person-days of community exposure from primary and secondary cases, respectively. Nevertheless, only 5 secondary cases occurred. Conclusions A large flight-related COVID-19 cluster was successfully contained through timely, systematic and comprehensive public health responses despite delayed index case identification. Multiagency collaboration and pre-established mechanisms are crucial for low and middle income countries like Vietnam to limit community transmission after COVID-19 importation through air travel.

To examine the willingness to pay (WTP) for a quality-adjusted life year (QALY) gained among advanced non-small cell lung cancer (NSCLC) patients in Viet Nam and to analyze the factors affecting an individual's WTP. A cross-sectional, contingent valuation study was conducted among 400 NSCLC patients across 6 national hospitals in Viet Nam. Self-reported information was recorded from patients regarding their socio-demographic status, EQ-5D (EuroQol-5 dimensions) utility, EQ-5D vas, and WTP for 1 QALY gained. To explore the factors related to the WTP, Gamma Generalized Linear Model and multiple logistic regression tools were applied to analyze data. The overall mean and median of WTP/QALY among the NSCLC patients were USD $11,301 and USD $8002, respectively. Strong association was recorded between WTP/QALY amount and the patient's education, economic status, comorbidity status, and health utility. Government and policymakers should consider providing financial supports to disadvantaged groups to improve their access to life saving cancer treatment.

Background Vietnam implemented various public health interventions such as contact tracing and testing, mandatory quarantine, and lockdowns in response to COVID-19. However, the effects of these measures on the epidemic remain unclear. Methods We described public health interventions in relation to COVID-19 incidence. We used maximum likelihood estimations to assess containment delays (time between symptom onset and start of isolation) and multivariable regression to identify associated factors between interventions and COVID-19 incidence. We calculated effective reproductive numbers (Rt) based on transmission pairs. Results Interventions were introduced periodically in response to the epidemic. 817 (55.4%) among 1,474 COVID-19 cases were imported. Based on a serial interval of 8.72 (±5.65) days, we estimated Rt to reduce below 1 (lowest at 0.02 (95%CI 0-0.12)) during periods of strict border control and contact tracing, and to increase ahead of new clusters. The main method to detect cases shifted over time from passive notification to active case finding at immigration or in lockdown areas, with containment delays showing significant differences between modes of case detection. Conclusion A combination of early, strict and consistently implemented of interventions is crucial to control COVID-19. Low-middle income countries with limited capacity can contain COVID-19 successfully using non-pharmaceutical interventions.

Background Community health workers (CHWs) involved in the COVID-19 response might be at increased risk of developing depression, though evidence is scarce. We investigated effects of COVID-19-related work on changes in depression levels among CHWs in Vietnam and identified sub-groups among CHWs who are at particular risk of developing severe depression. Methods We conducted a cross-sectional online survey among 979 CHWs who were involved in the COVID-19 response in Vietnam, in particular during the 2021 Tet holiday outbreak between January and March 2021. Respondents were asked to report depression symptoms at two-time points, before the start of the COVID-19 pandemic (average June to December 2019) and during the 2021 Tet holiday outbreak using the PHQ-9 mental health questionnaire. We estimated depression levels at both time points and developed univariate and multivariable logistic regression models to estimate odds ratios and 95% confidence intervals (95% CIs) to explore the association between deterioration to high depression levels and selected risk factors. Results Median depression levels among CHWs in Vietnam doubled from 3 (IQR = 2–7) before COVID-19 to 6 (IQR = 3–9) on the PHQ-9 scale during the Tet holiday outbreak. The proportion with normal/minimal levels decreased from 77.1% (95% CI = 74.4–79.7) to 50.9% (95% CI = 47.7–54) (p-value < 0.001), while the proportion of CHWs with moderate, moderately severe, and severe depression levels increased 4.3, 4.5, and five-fold, respectively. Less sleep and poor sleep quality, working in unfavorable work environments, and being involved in contact tracing and the organization of quarantine for suspected cases were associated with an increased risk of deterioration to high depression levels. Conclusions We found a substantial increase in overall depression levels among CHWs in Vietnam due to their COVID-19 related work and a particularly worrisome rise in CHWs suffering from severe depression. CHWs are an indispensable yet often overlooked cadre of work in many low- and middle-income countries and shoulder a heavy psychological burden during the COVID-19 pandemic. Targeted psychological support for CHWs is needed to improve their mental health and to ensure the sustainability of community-based health interventions during COVID-19 and future epidemics.