Virologic Characteristics of Cases of COVID-19 in Northern Vietnam, January -- May, 2020
Bibliographic record
Abstract
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.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".