In 2004, 185 specimens of patients with acute respiratory illnesses that were tested negative to influenza viruses were isolated to determine enteroviruses. The results showed that 10.8% were positive with enteroviruses. These isolated enteroviruses consist of 13 Coxsackievirus B, 1 Echovirus, 1 Poliosabin type 1, and 5 untyped Enteroviruses. The result also showed that 8.1% of isolated viruses were Adenoviruses
Respiratory Tract Infections ; Orthomyxoviridae

Introduction: Antiviral resistance has been reported in seasonal influenza A viruses and avian influenza A(H5N1) viruses in Viet Nam, raising concerns about the efficacy of treatment. Methods: We analysed specimens from two sources during the period 2009–2012: influenza-positive samples from influenza-like illness patients at sentinel clinics in northern Viet Nam and isolates from patients with confirmed A(H5N1) infections. Pyrosequencing was used to detect mutations: H275Y [for A(H1N1) and A(H5N1)], E119V [for A(H3N2)] and I117V [for A(H5N1)]. A neuraminidase inhibition assay was used to determine the Inhibitory Concentration 50 (IC50) values for all influenza A and B isolates. Results: There were 341 influenza A positive samples identified; influenza A(H1N1)pdm09 was identified most frequently (n = 215). In 2009, oseltamivir resistance was observed in 100% (19 of 19) of seasonal A(H1N1) isolates and 1.4% (3/215) of A(H1N1)pdm09 isolates. This H275Y mutation was not found in influenza subtypes A(H5N1) or A(H3N2) isolates. Discussion: In Viet Nam, seasonal and A(H5N1) influenza vaccines are not currently available; thus, effective treatment is required. The presence of oseltamivir-resistant viruses is therefore a concern. Active surveillance for oseltamivir resistance among influenza viruses circulating in Viet Nam should be continued.

Objective:Highly pathogenic avian influenza A(H5N1) is endemic in poultry in Viet Nam. The country has experienced the third highest number of human infections with influenza A(H5N1) in the world. A study in Hanoi in 2001, before the epizootic that was identified in 2003, found influenza A(H5N1) specific antibodies in 4% of poultry market workers (PMWs). We conducted a seroprevalence survey to determine the seroprevalence of antibodies to influenza A(H5N1) among PMWs in Hanoi, Thaibinh and Thanhhoa provinces.Methods:We selected PMWs from five markets, interviewed them and collected blood samples. These were then tested using a horse haemagglutination inhibition assay and a microneutralization assay with all three clades of influenza A(H5N1) viruses that have circulated in Viet Nam since 2004.Results:The overall seroprevalence was 6.1% (95% confidence interval: 4.6–8.3). The highest proportion (7.2%) was found in PMWs in Hanoi, and the majority of seropositive subjects (70.3%) were slaughterers or sellers of poultry.Discussion:The continued circulation and evolution of influenza A(H5N1) requires comprehensive surveillance of both human and animal sites throughout the country with follow-up studies on PMWs to estimate the risk of avian–human transmission of influenza A(H5N1) in Viet Nam.

BACKGROUND: The diagnosis of influenza based on clinical grounds alone may be inaccurate, because the presenting symptoms of influenza are similar to those caused by other infectious agents. We evaluate two influenza rapid tests, SD BIOLINE Influenza Ag (Standard Diagnostic inc., Yongin, Korea) and QuickVueTM Influenza Test (Quidel corporation, San Diego, USA) with influenza virus culture and RT-PCR. METHODS: The two commercially available rapid test kits, SD BIOLINE Influenza Ag and QuickVueTM Influenza Test, for influenza virus detection were evaluated with 189 respiratory specimens collected during Dec. 2004 to Nov. 2005 in Vietnam and compared with viral culture and RT-PCR. RESULTS: Overall, the SD BIOLINE Influenza Ag and QuickVueTM Influenza Test showed high sensitivities (88.4% and 82.6%, respectively) and high specificities (99.0% and 99.0%, respectively), high positive predictive value (PPV) (98.7% and 98.6%, respectively) and high negative predictive value (NPV) (91.1% and 87.2%, respectively). CONCLUSION: Both SD BIOLINE Influenza Ag and QuickVueTM Influenza Test were easy to perform and showed high sensitivity and can be used as an additional tool for rapid diagnosis of influenza virus.
Diagnosis ; Gyeonggi-do ; Immunoassay* ; Influenza, Human* ; Membranes* ; Orthomyxoviridae* ; Sensitivity and Specificity ; Vietnam

This article describes Viet Nam Ministry of Health’s (VMoH) activities to prepare for and respond to the threat Zika virus (ZIKV), including the adaptation of existing surveillance systems to encompass ZIKV surveillance.

Objective To characterize viral co-infections among representative hospitalized measles cases during the 2014 Hanoi outbreak. Methods Throat swabs were collected from 54 pediatric patients with confirmed measles, and molecular diagnostics performed for 10 additional viral respiratory pathogens (Influenza A/H1N1pdm09; A/H3N2 and influenza B; Parainfluenza 1, 2, 3; Respiratory Synctial Virus, RSV; human Metapneumovirus, hMPV; Adenovirus and Picornavirus). Results Twenty-one cases (38.9%) showed evidence of infection with other respiratory viruses: 15 samples contained measles plus one additional virus, and 6 samples contained measles plus 2 additional viruses. Adenovirus was detected as a predominant cause of co-infections (13 cases; 24.1%), followed by RSV (6 cases; 11.1%), A/H1N1pdm09 (3 cases; 5.6%), PIV3 (3 cases; 3.7%), Rhinovirus (3 cases; 3.7%) and hMPV (1 case; 1.96%). Conclusions Viral co-infections identified from pediatric measles cases may have contributed to increased disease severity and high rate of fatal outcomes. Optimal treatment of measles cases may require control of multiple viral respiratory pathogens.

Background: Viet Nam confirmed its first case of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on 23 January 2020 among travellers from Wuhan, China, and experienced several clusters of community transmission until September. Viet Nam implemented an aggressive testing, isolation, contact tracing and quarantine strategy in response to all laboratory-confirmed cases. We report the results of SARS-CoV-2 testing during the first half of 2020 in northern Viet Nam. Methods: Between January and May 2020, 15 650 upper respiratory tract specimens were collected from 14 470 suspected cases and contacts in northern Viet Nam. All were tested for SARS-CoV-2 by real-time RT-PCR. Individuals with positive specimens were tested every three days until two tests were negative. Positive specimens from 81 individuals were cultured. Results: Among 14 470 tested individuals, 158 (1.1%) cases of SARS-CoV-2 infection were confirmed; 89 were imported and 69 were associated with community transmission. Most patients (122, 77%) had negative results after two tests, while 11 and 4 still tested positive when sampled a third and fourth time, respectively. SARS-CoV-2 was isolated from 29 of 81 specimens (36%) with a cycle threshold (Ct) value <30. Seven patients who tested positive again after testing negative had Ct values >30 and negative cultures. Conclusion Early, widespread testing for SARS-CoV-2 in northern Viet Nam identified very few cases, which, when combined with other aggressive strategies, may have dramatically contained the epidemic. We observed rapid viral clearance and very few positive results after clearance. Large-scale molecular diagnostic testing is a critical part of early detection and containment of COVID-19 in Viet Nam and will remain necessary until vaccination is widely implemented.

Objective: Human respiratory syncytial virus (RSV) is a primary cause of paediatric severe acute respiratory infection (SARI) worldwide, especially in developing countries. We investigated the genetic characteristics of RSV in northern Viet Nam to determine the prevalence and distribution of subtypes as well as the diversity and transmission patterns of genotypes. Methods: In two facilities, from January 2017 to December 2020, 1563 clinical specimens were collected from paediatric patients hospitalized with SARI and tested for RSV. Selected positive samples underwent sequencing analysis targeting the second hypervariable region of the G gene using next-generation sequencing. Results: The RSV positivity rate was 28.02% (438/1563 samples), and prevalence was highest in children aged <1 year (43.84%; 192/438). Subtype RSV-A accounted for 53.42% (234/438) of cases, RSV-B for 45.89% (201/438), and there was coinfection in 0.68% (3/438). Both subtypes cocirculated and peaked during August–September in each year of the study. Phylogenetic analysis showed that RSV-A samples belonged to the ON1 genotype, which has three subgenotypes: ON1.1, ON1.2 and ON1.3. However, we did not find the 72-nucleotide duplication in the second hypervariable region of the G gene, a characteristic of genotype ON1, in any RSV-A samples. RSV-B samples belonged to genotype BA9. Discussion: Our results provide additional molecular characterization of RSV infections in Viet Nam. Specially, our study is the first to report the absence of the 72-nucleotide duplication in the G gene of RSV-A genotype ON1 in Viet Nam, which may help in understanding the genetic evolution of RSV and be useful for vaccine development in the future.

The Omicron variant caused a surge of infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Viet Nam in early 2022, signalling community transmission. We report on active whole-genome sequencing surveillance of positive SARS-CoV-2 samples collected at that time in northern Viet Nam from international arrivals and community clusters. We used an amplicon protocol developed with 14 polymerase chain reaction products and the Illumina iSeq 100 platform. Overall, 213 nasopharyngeal or throat swabs were analysed, of which 172 samples were identified with the Omicron variant. Of these, 80 samples were collected from community cases in February 2022, among which 59 samples were sublineage BA.2 and one sample was the recombinant XE variant. Our results indicated that Omicron had replaced Delta as the dominant variant in a very short period of time and that continuously conducting active whole-genome sequencing surveillance is necessary in monitoring the evolution and genomic diversity of SARS-CoV-2 in Viet Nam.