Le Thi Khanh Ly

Rotavin-M1 (POLYVAC) was licensed in Vietnam in 2012. The association of Rotavin-M1 with intussusception, a rare adverse event associated with rotavirus vaccines, and with adverse events following immunization (AEFI) have not been evaluated and monitored under conditions of routine use. From February 2017 to May 2021, we conducted a pilot introduction of Rotavin-M1 into the routine vaccination program in two provinces. Surveillance for intussusception was conducted at six sentinel hospitals. AEFI reports at 30 min and 7 days after vaccination were recorded. Among 443 children ®, ComBE Five^®) compared to Rotavin-M1 without pentavalent vaccines. There was no association between intussusception and Rotavin-M1. The vaccine was generally safe when administered alone and when co-administered with other vaccines.

Rotavirus (RV), norovirus (NoV), sapovirus (SaV), and human astrovirus (HAstV) are the most common viral causes of gastroenteritis in children worldwide. From 2016 to 2021, we conducted a cross-sectional descriptive study to determine the prevalence of these viruses in hospitalized children under five years old in Nam Dinh and Thua Thien Hue provinces in Vietnam during the pilot introduction of the RV vaccine, Rotavin-M1 (POLYVAC, Hanoi, Vietnam). We randomly selected 2317/6718 (34%) acute diarrheal samples from children ®, Meridian Bioscience, Inc., Cincinnati, OH, USA) was used to detect RV, and two multiplex real-time RT-PCR assays were used for the detection of NoV, SaV and HAstV. The prevalence of RV (single infection) was reduced from 41.6% to 22.7% (p < 0.0001) between pre- and post-vaccination periods, while the single NoV infection prevalence more than doubled from 8.8% to 21.8% (p < 0.0001). The SaV and HAstV prevalences slightly increased from 1.9% to 3.4% (p = 0.03) and 2.1% to 3.3% (p = 0.09), respectively, during the same period. Viral co-infections decreased from 7.2% to 6.0% (p = 0.24), mainly due to a reduction in RV infection. Among the genotypeable samples, NoV GII.4, SaV GI.1, and HAstV-1 were the dominant types, representing 57.3%, 32.1%, and 55.0% among the individual viral groups, respectively. As the prevalence of RV decreases following the national RV vaccine introduction in Vietnam, other viral pathogens account for a larger proportion of the remaining diarrhea burden and require continuing close monitoring.

Background: Female sex workers (FSWs) are at high risk of human papillomavirus (HPV) infections and cervical cancer due to their high number of sexual partners. The objectives of this study were to determine the prevalence of HPV and identify risk factors for high-risk HPV infection among FSWs in Hanoi and Ho Chi Minh City (HCMC), Viet Nam. Methods: A cross-sectional study was conducted in Hanoi and HCMC between December 2017 and May 2018. We surveyed and screened 699 FSWs aged >18 years for HPV infection and abnormal cytology. A multivariable modified Cox regression model was used to determine risk factors for high-risk HPV infection. Results: The overall prevalence of any HPV, high-risk HPV and HPV-16/18 infection in the 699 FSWs was 26.3%, 17.6% and 4.0%, respectively, and were similar in both cities. Multiple infections were identified in 127 participants (69.0%). HPV-52 was the most prevalent (7%), followed by HPV-58 (6%). Abnormal cytology was detected in 91 participants (13.0%). FSWs who are divorced (adjusted prevalence ratio [aPR]: 1.96, 95% confidence interval [CI]: 1.01–3.81), widowed (aPR: 3.26, 95% CI: 1.49–7.12) or living alone (aPR: 1.85, 95% CI: 1.01–3.39) were associated with a higher prevalence of high-risk HPV infection. Discussion: Almost one in five FSWs in Viet Nam are infected with high-risk HPV. This highlights the importance of prevention strategies such as HPV vaccination and screening in this high-risk group.

Vi rút Rota G1P[8] là một trong các kiểu gen phổ biến trên thế giới. Cho đến 2013 chủng G1P[8] có tỷ lệ lưu hành cao nhất trước khi chủng G3 trở nên phổ biến từ 2015 - 2016. Ba vắc xin phòng vi rút Rota cấp phép tại Việt Nam đều là vắc xin sống, giảm độc lực, chứa thành phần G1 và P[8]. Nghiên cứu này nhằm theo dõi sự lưu hành của kiểu gen G1P[8] từ 2016 - 2021 và đánh giá mối liên quan giữa việc tái xuất hiện của kiểu gen này với việc sử dụng vắc xin Rotavin-M1 ở tỉnh Nam Định. Bằng phương pháp RT-PCR với mồi đặc hiệu, chúng tôi phát hiện kiểu gen G1P[8] với tỷ lệ cao 23,2% từ 6/2020 - 5/2021 sau 4 năm hiếm gặp (tỷ lệ phát hiện 0 - 2,4%). Phân tích độ tương đồng trình tự gen VP4 (876bp) và VP7 (1062bp) và cây phát sinh chủng loại cho thấy các chủng phát hiện được ở thời điểm này thuộc GI-dòng II và P[8] - dòng III, khác với chủng vắc xin Rotavin-M1, Rotarix và Rotateq. Các chủng này khác biệt 2 - 3 axit amin với Rotavin-M1 và Rotateq trong vùng gen VP7; khác 2 - 4 axit amin với Rotavin-M1 và Rotarix trong vùng gen VP4. Kết quả cho thấy chủng G1P[8] đang phổ biến ở Nam Định không có nguồn gốc từ vắc xin. Cần tiếp tục theo dõi sự lưu hành của kiểu gen G1P[8] này trong tương lai.

Rotavirus (RV), Norovirus (NV), Sapovirus (SaV) and Astrovirus (Ast) are the leading causes of gastroenteritis and mortality in children worldwide. RV vaccines help to reduce the burden of diarrhea while the importance of other viruses is increasing. Therefore, we conducted a cross-sectional descriptive study to determine prevalence of these viruses in hospitalized children under 5 years old in Nam Dinh province with approximately 80% of RV vaccine coverage. We randomly selected 579 (25%) among diarrheal samples collected in 4 district hospitals from Dec. 2017 to Nov. 2019. An ELISA kit was employed to detect RV and the multiplex real-time RT-PCR with specific primers to detect NV, SaV and Ast. These viruses were found among 64.3% of hospitalized children, of which NV and RV were present in 28.5% and 21.4%, respectively, while SaV and Ast were detected in 3.3% and 2.6%, respectively. Co-infections accounted for 8.5%, mainly among RV and 3 other viruses. There is a significant difference in RV and NV positive rates between vaccinated and unvaccinated groups (p < 0.001 and p = 0.008, respectively). This study contributed to the understanding of the potential impact of rotavirus vaccine on other diarheal pathogens and emphasize the need for further epidemiological studies when the nationwide RV vaccination in Vietnam is implementing.

Rotavirus (RV) is the most common cause of severe childhood diarrhea worldwide. Since 2006, the WHO has approved the use of two vaccines against Rotavirus (RotaTeq and Rotarix), which has contributed to a significant reduction in morbidity and mortality from this disease in children under 5 years of age. Beside of that, the presence of vaccines could also cause selective pressure among circulating RV strains. Diarrhea samples were a part of the study of the project “Evaluation of rotavirus vaccine effectiveness in Vietnam” and some diarrhea samples were randomly selected from 2010 - 2015 and were stored in our laboratory. Rotavirus antigen in diarrhea samples was detected using the Premier Rotaclone kit. G and P genotypes were determined by RT-PCR using type specific primers. The nucleotide sequencewas determined by next generation sequencing and phylogenetic analysis was performed by the neighbor-joining method. 375/1715 (21.9%) samples detected G3 strain include equine-like G3 (eG3) and human G3 (hG3). The prevalence of G3 strains decreased from 2016 to 2021. All eleven gene segments were typed among 34 samples and substantial diversity among the circulating strains was observed. The circulating G3 strains were also phylogenetically diverse and related to strains from several different countries, different origins such as human (20 samples), pig (1 sample), cat (3 samples) and equine (10 samples). Comparing with the vaccine strains, the antigenic epitopes present on VP7 ofG3 in Vietnam differed considerably, especially the K238N. With the genetic characteristics of the G3 strain, it could contribute to the vaccine effectiveness in Vietnam.

Human papillomavirus (HPV) 68 là một trong các týp HPV nguy cơ cao gây ung thư cổ tử cung với tỷ lệ nhiễm chỉ sau HPV52, 16 và 18. Mặc dù vậy các vắc xin phòng HPV hiện nay không bao gồm týp vi rút này. Hơn nữa thông tin về đặc điểm di truyền của týp này còn rất hạn chế. Vì vậy, chúng tôi tiến hành nghiên cứu này nhằm phân tích di truyền của 12 chủng HPV68 phân lập từ 3076 bệnh phẩm của phụ nữ tại Hà Nội và Thành phố Hồ Chí Minh bằng giải trình tự gen. Dựa trên sự khác biệt trình tự nucleotit vùng gen L1, E6 và E7, các dòng của HPV68 được xác định bằng phương pháp maximum likelihood, trong khi đó các vị trí đa hình nucleotit và biến đổi axit amin được so sánh với trình tự gốc (chủng prototype). Kết quả cho thấy HPV68 dòng C chiếm 80% số mẫu HPV68 phát hiện được. Gen L1 có tần suất đa hình nucleotit cao nhất (8,2%) và protein E7 có tỷ lệ axit amin biến đổi cao nhất trong 3 gen nghiên cứu (11,7%). Trong số các vị trí đa hình dẫn đến thay thế axit amin, Y18C và Q22E tìm thấy ở các chủng HPV68 tại Việt Nam nằm trong vùng tương tác giữa protein E7 và Rb1. Tuy nhiên, ảnh hưởng của các đa hình và biến đổi axit amin đến khả năng hình thành ung thư cần được nghiên cứu sâu hơn.

Background/Aim: Cervical cancer is the second most common malignancy among women in Vietnam, but the country is yet to introduce a national human papillomavirus (HPV) vaccine programme targeted at adolescents. We determined HPV prevalence and HPV vaccine knowledge among female university students in Vietnam. Patients and Methods: We surveyed and screened 1,491 female university students in Hanoi, Hue, and Ho Chi Minh City for their sexual behaviours, HPV knowledge and low- and high-risk HPV infection. Results: The prevalence of any HPV infection and any high-risk HPV infection were 4.2% (95%CI=3.3%-5.4%) and 3.4% (95%CI=2.5%-4.4%), respectively. Being sexually active [adjusted prevalence ratio (aPR): 6.22; 95%CI=3.4-11.37] and having ever been pregnant (aPR: 4.82; 95%CI=1.93-12.04) were positively associated with high-risk HPV infection. Whilst 60% of participants had heard of HPV vaccine, only 4.6% had received the vaccine. Conclusion: The low HPV prevalence found in university students in Vietnam indicates that they can benefit from HPV vaccination, along with a well-designed HPV health promotion programme.