Objective: The risk of transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from schoolchildren to their household and the protective effects of vaccination in these settings remain poorly understood. We assessed the transmission dynamics of schoolchildren with SARS-CoV-2 within their households and the protective effects of coronavirus disease (COVID-19) vaccination among household members in Viet Nam. Methods: We estimated the attack rate, vaccine effectiveness and adjusted risk ratio (aRR) of factors associated with SARS-CoV-2 transmission to household contacts of children confirmed to have COVID-19 who attended three schools in Ha Nam, Phu Tho and Thanh Hoa provinces between September and December 2021 using multivariable regression with household-level random effects. Results: This retrospective cohort study included 157 children infected with SARS-CoV-2 and their 540 household contacts. The attack rate among household contacts was 24.6% (133/540). Overall, vaccine effectiveness among household contacts was 39% (95% confidence interval [CI]: -1 to -63), higher among males than females and higher in adults aged >40 years. COVID-19 transmission was greater among female household contacts compared with males (aRR: 1.35, 95% CI: 0.94 to 1.95), although not statistically significant, and highest among those aged 19–39 years (aRR: 2.51, 95% CI: 1.50 to 4.21). Fully vaccinated household contacts had significantly lower infection risk (aRR: 0.46, 95% CI: 0.26 to 0.84). Discussion: We found substantial onward transmission of SARS-CoV-2 from schoolchildren to household members, and older people were more likely to be protected by vaccination. We recommend that schoolchildren and all household members living with schoolchildren receive at least two doses of a COVID-19 vaccine. Recognizing the role of schoolchildren in the onward transmission of COVID-19 is an important lesson learned by Viet Nam that can help not only in managing other outbreaks but also in protecting schoolchildren by predicting the progress of the outbreak and preparing for a timely response.

Vietnam boasts a rich and diverse flora, with many endemic species. Among them, Ngoc Linh ginseng (Vietnamese ginseng; scientific name: Panax vietnamensis Ha et Grushv.), a high-value endemic ginseng species, has been recognized as a national treasure. While numerous studies have been conducted on its rhizomes and roots, research on its leaves remains limited. In this study, six compounds (1–6) were isolated from the methanol extract of the leaves of P. vietnamensis. Their structures were elucidated using ESI-MS, 1D and 2D NMR spectroscopic methods, and comparisons with known literature data. The identified compounds are: 12β,20(R),25-β trihydroxydammara-3-O-β-D-glucopyranoside (1); 12β,20(R),25-trihydroxydammara-3-O-β-D-glucopyranosyl- (1→2)-β-D-glucopyranoside (2); notoginsenoside SFt1 (3); ginsenoside Rh2 (4); ginsenoside Rg3 (5) and notoginsenoside L1 (6). Except for compound 3, which was isolated from the leaves for the first time, the other five compounds are reported from this species for the first time. The α-glucosidase inhibition assay of the pure isolated compounds revealed that compounds 1, 4, and 6 exhibited significant activities, with IC50 values of 133.5, 105.5, and 14.9, respectively. For comparison, the positive control, acarbose, had an IC50 value of 138.2 µM.

A new crinane-type alkaloid, 6-epihydroxypowelline (1), together with six known alkaloids, lycorine (2), 2-O-acetyllycorine (3), deacetylbowdensine (4), 1-epideacetylbowdensine (5), 8-demethyl-3-oxomaritidine (6), and (-)-marithamine (7) were isolated from the whole parts of the Crinum latifolium L. in Vietnam. The structure identification of all compounds was determined by 1D, 2D-NMR as well as HR-ESI-MS spectroscopic techniques. The absolute configuration of these compounds was established by the ECD data. In addition, in vitro inhibition of acetylcholinesterase (AChE) activities was assessed for all isolated alkaloids. All alkaloids had AChE inhibitory effects, with IC50 values ranging from 32.65 ± 2.72 to 212.76 ± 8.30 µM and compound 3 displayed the strongest inhibition of AChE, with IC50 values of 32.65 ± 2.72 µM (in comparison to the reference drug, galanthamine, which had an IC50 of 2.40 ± 0.45 µM).

Vietnam boasts a rich and diverse flora, with many endemic species. Among them, Ngoc Linh ginseng (Vietnamese ginseng; scientific name: Panax vietnamensis Ha et Grushv.), a high-value endemic ginseng species, has been recognized as a national treasure. While numerous studies have been conducted on its rhizomes and roots, research on its leaves remains limited. In this study, six compounds (1–6) were isolated from the methanol extract of the leaves of P. vietnamensis. Their structures were elucidated using ESI-MS, 1D and 2D NMR spectroscopic methods, and comparisons with known literature data. The identified compounds are: 12β,20(R),25-β trihydroxydammara-3-O-β-D-glucopyranoside (1); 12β,20(R),25-trihydroxydammara-3-O-β-D-glucopyranosyl- (1→2)-β-D-glucopyranoside (2); notoginsenoside SFt1 (3); ginsenoside Rh2 (4); ginsenoside Rg3 (5) and notoginsenoside L1 (6). Except for compound 3, which was isolated from the leaves for the first time, the other five compounds are reported from this species for the first time. The α-glucosidase inhibition assay of the pure isolated compounds revealed that compounds 1, 4, and 6 exhibited significant activities, with IC50 values of 133.5, 105.5, and 14.9, respectively. For comparison, the positive control, acarbose, had an IC50 value of 138.2 µM.

A new crinane-type alkaloid, 6-epihydroxypowelline (1), together with six known alkaloids, lycorine (2), 2-O-acetyllycorine (3), deacetylbowdensine (4), 1-epideacetylbowdensine (5), 8-demethyl-3-oxomaritidine (6), and (-)-marithamine (7) were isolated from the whole parts of the Crinum latifolium L. in Vietnam. The structure identification of all compounds was determined by 1D, 2D-NMR as well as HR-ESI-MS spectroscopic techniques. The absolute configuration of these compounds was established by the ECD data. In addition, in vitro inhibition of acetylcholinesterase (AChE) activities was assessed for all isolated alkaloids. All alkaloids had AChE inhibitory effects, with IC50 values ranging from 32.65 ± 2.72 to 212.76 ± 8.30 µM and compound 3 displayed the strongest inhibition of AChE, with IC50 values of 32.65 ± 2.72 µM (in comparison to the reference drug, galanthamine, which had an IC50 of 2.40 ± 0.45 µM).

Vietnam boasts a rich and diverse flora, with many endemic species. Among them, Ngoc Linh ginseng (Vietnamese ginseng; scientific name: Panax vietnamensis Ha et Grushv.), a high-value endemic ginseng species, has been recognized as a national treasure. While numerous studies have been conducted on its rhizomes and roots, research on its leaves remains limited. In this study, six compounds (1–6) were isolated from the methanol extract of the leaves of P. vietnamensis. Their structures were elucidated using ESI-MS, 1D and 2D NMR spectroscopic methods, and comparisons with known literature data. The identified compounds are: 12β,20(R),25-β trihydroxydammara-3-O-β-D-glucopyranoside (1); 12β,20(R),25-trihydroxydammara-3-O-β-D-glucopyranosyl- (1→2)-β-D-glucopyranoside (2); notoginsenoside SFt1 (3); ginsenoside Rh2 (4); ginsenoside Rg3 (5) and notoginsenoside L1 (6). Except for compound 3, which was isolated from the leaves for the first time, the other five compounds are reported from this species for the first time. The α-glucosidase inhibition assay of the pure isolated compounds revealed that compounds 1, 4, and 6 exhibited significant activities, with IC50 values of 133.5, 105.5, and 14.9, respectively. For comparison, the positive control, acarbose, had an IC50 value of 138.2 µM.

A new crinane-type alkaloid, 6-epihydroxypowelline (1), together with six known alkaloids, lycorine (2), 2-O-acetyllycorine (3), deacetylbowdensine (4), 1-epideacetylbowdensine (5), 8-demethyl-3-oxomaritidine (6), and (-)-marithamine (7) were isolated from the whole parts of the Crinum latifolium L. in Vietnam. The structure identification of all compounds was determined by 1D, 2D-NMR as well as HR-ESI-MS spectroscopic techniques. The absolute configuration of these compounds was established by the ECD data. In addition, in vitro inhibition of acetylcholinesterase (AChE) activities was assessed for all isolated alkaloids. All alkaloids had AChE inhibitory effects, with IC50 values ranging from 32.65 ± 2.72 to 212.76 ± 8.30 µM and compound 3 displayed the strongest inhibition of AChE, with IC50 values of 32.65 ± 2.72 µM (in comparison to the reference drug, galanthamine, which had an IC50 of 2.40 ± 0.45 µM).

Vietnam boasts a rich and diverse flora, with many endemic species. Among them, Ngoc Linh ginseng (Vietnamese ginseng; scientific name: Panax vietnamensis Ha et Grushv.), a high-value endemic ginseng species, has been recognized as a national treasure. While numerous studies have been conducted on its rhizomes and roots, research on its leaves remains limited. In this study, six compounds (1–6) were isolated from the methanol extract of the leaves of P. vietnamensis. Their structures were elucidated using ESI-MS, 1D and 2D NMR spectroscopic methods, and comparisons with known literature data. The identified compounds are: 12β,20(R),25-β trihydroxydammara-3-O-β-D-glucopyranoside (1); 12β,20(R),25-trihydroxydammara-3-O-β-D-glucopyranosyl- (1→2)-β-D-glucopyranoside (2); notoginsenoside SFt1 (3); ginsenoside Rh2 (4); ginsenoside Rg3 (5) and notoginsenoside L1 (6). Except for compound 3, which was isolated from the leaves for the first time, the other five compounds are reported from this species for the first time. The α-glucosidase inhibition assay of the pure isolated compounds revealed that compounds 1, 4, and 6 exhibited significant activities, with IC50 values of 133.5, 105.5, and 14.9, respectively. For comparison, the positive control, acarbose, had an IC50 value of 138.2 µM.

A new crinane-type alkaloid, 6-epihydroxypowelline (1), together with six known alkaloids, lycorine (2), 2-O-acetyllycorine (3), deacetylbowdensine (4), 1-epideacetylbowdensine (5), 8-demethyl-3-oxomaritidine (6), and (-)-marithamine (7) were isolated from the whole parts of the Crinum latifolium L. in Vietnam. The structure identification of all compounds was determined by 1D, 2D-NMR as well as HR-ESI-MS spectroscopic techniques. The absolute configuration of these compounds was established by the ECD data. In addition, in vitro inhibition of acetylcholinesterase (AChE) activities was assessed for all isolated alkaloids. All alkaloids had AChE inhibitory effects, with IC50 values ranging from 32.65 ± 2.72 to 212.76 ± 8.30 µM and compound 3 displayed the strongest inhibition of AChE, with IC50 values of 32.65 ± 2.72 µM (in comparison to the reference drug, galanthamine, which had an IC50 of 2.40 ± 0.45 µM).

Vietnam boasts a rich and diverse flora, with many endemic species. Among them, Ngoc Linh ginseng (Vietnamese ginseng; scientific name: Panax vietnamensis Ha et Grushv.), a high-value endemic ginseng species, has been recognized as a national treasure. While numerous studies have been conducted on its rhizomes and roots, research on its leaves remains limited. In this study, six compounds (1–6) were isolated from the methanol extract of the leaves of P. vietnamensis. Their structures were elucidated using ESI-MS, 1D and 2D NMR spectroscopic methods, and comparisons with known literature data. The identified compounds are: 12β,20(R),25-β trihydroxydammara-3-O-β-D-glucopyranoside (1); 12β,20(R),25-trihydroxydammara-3-O-β-D-glucopyranosyl- (1→2)-β-D-glucopyranoside (2); notoginsenoside SFt1 (3); ginsenoside Rh2 (4); ginsenoside Rg3 (5) and notoginsenoside L1 (6). Except for compound 3, which was isolated from the leaves for the first time, the other five compounds are reported from this species for the first time. The α-glucosidase inhibition assay of the pure isolated compounds revealed that compounds 1, 4, and 6 exhibited significant activities, with IC50 values of 133.5, 105.5, and 14.9, respectively. For comparison, the positive control, acarbose, had an IC50 value of 138.2 µM.