Hang Khanh Le Nguyen 1, Son Vu
Nguyen1, Phuong Mai Vu Hoang1, Thanh
thi Le1, Huong thi Thu Tran 1, Long
Hai Pham Nguyen2, Thai Quang Pham1,
Thuy thanh Nguyen1, Anh Duc Dang1,
Mai thi Quynh Le1.
- National Institute of Hygiene and Epidemiology, Hanoi,
Vietnam
- Mohawk college, Hamilton, ON, Canada
Corresponding author : Mai thi Quynh Le,
National Influenza Center – National Institute of Hygiene and
Epidemiology, Hanoi, Vietnam.
Fax: + 84 4 3 8210853
Phone: + 84 912126283
Email: lom9@hotmail.com or lom9@nihe.org.vn.
Background: Vietnam confirmed its first case of SARS-CoV-2
infection on January 23, 2020 among travelers from Wuhan, China and
experienced several clusters of community transmission until September.
Vietnam 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 Vietnam.
Methods: From January through May, 2020, 15,650 upper
respiratory specimens were collected from 14,470 suspected cases and
contacts in northern Vietnam. All were tested for SARS-CoV-2 by
real-time RT-PCR. Individuals with positive specimens were tested every
3 days until negative twice. 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%) became
negative after two tests, with 11 and 4 still testing positive when
sampled a fourth and fifth time, respectively. Among 81 specimens with
Ct values <30, SARS-CoV-2 was isolated from 29 (36%). Seven
patients testing positive again after testing negative had Ct values
>30 and negative culture.
Conclusion: Early and widespread testing for SARS-CoV-2 in
northern Vietnam 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 following clearance. Large scale molecular diagnostic testing is
a critical part of early detection and containment of COVID-19 in
Vietnam and will remain necessary until a vaccine is widely implemented.
Keyword: COVID-19; SARS-CoV-2; real-time RT-PCR, viral culture;
containment.