SARS-CoV-2 molecular diagnostic point-of-care testing based on loop-mediated isothermal amplification: A prospective, single-center validation study

Objectives Rapid and accurate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostic tests are crucial for controlling the spread of infections in emergency settings. This study evaluated the diagnostic accuracy of a point-of-care (POC) test based on loop-mediated isothermal amplification (LAMP) that produces rapid results within 30 min. Methods We prospectively included adult patients (age >19 years) who were diagnosed with SARS-CoV-2 infection within the last 3 days and symptomatic patients who had visited the emergency room. Posterior nasopharyngeal (PNP) swabs and throat swabs collected by physicians were used to test the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy, and Cohen's Kappa coefficient (k) of the POC index and reference reverse transcription quantitative polymerase chain reaction (RT-qPCR) test devices. Results Of the 352 participants, 102 (29.0%) tested positive via the RT-PCR-based reference test device;the RT-LAMP-based POC test had a sensitivity of 70.6% and specificity of 98.0%, with 93.5% PPV, 89.1% NPV, 35.5% PLR, and 3.4% NLR. Cohen's k correlation of results from the two devices was 0.74. The cycle threshold value between the positive and negative POC test results differed (17.6 vs. 24.6, p < 0.001). Conclusions The RT-LAMP POC test in the emergency medical setting has a fair predictive value in high viral load cases in terms of infectivity.

Maternal and Neonatal Outcomes in Pregnant Women With Coronavirus Disease 2019 in Korea.

BACKGROUND: This study aimed to describe the maternal, obstetrical, and neonatal outcomes in pregnant women with coronavirus disease 2019 (COVID-19) and identify the predictors associated with the severity of COVID-19. METHODS: This multicenter observational study included consecutive pregnant women admitted because of COVID-19 confirmed using reverse transcriptase-polymerase chain reaction (RT-PCR) test at 15 hospitals in the Republic of Korea between January 2020 and December 2021. RESULTS: A total of 257 women with COVID-19 and 62 newborns were included in this study. Most of the patients developed this disease during the third trimester. Nine patients (7.4%) developed pregnancy-related complications. All pregnant women received inpatient treatment, of whom 9 (3.5%) required intensive care, but none of them died. The gestational age at COVID-19 diagnosis (odds ratio [OR], 1.096, 95% confidence interval [CI], 1.04-1.15) and parity (OR, 1.703, 95% CI, 1.13-2.57) were identified as significant risk factors of severe diseases. Among women who delivered, 78.5% underwent cesarean section. Preterm birth (38.5%), premature rupture of membranes (7.7%), and miscarriage (4.6%) occurred, but there was no stillbirth or neonatal death. The RT-PCR test of newborns' amniotic fluid and umbilical cord blood samples was negative for severe acute respiratory syndrome coronavirus 2. CONCLUSION: At the time of COVID-19 diagnosis, gestational age and parity of pregnant women were the risk factors of disease severity. Vertical transmission of COVID-19 was not observed, and maternal severity did not significantly affect the neonatal prognosis.

Enhanced antibody responses in fully vaccinated individuals against pan-SARS-CoV-2 variants following Omicron breakthrough infection.

Omicron has become the globally dominant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant, creating additional challenges due to its ability to evade neutralization. Here, we report that neutralizing antibodies against Omicron variants are undetected following COVID-19 infection with ancestral or past SARS-CoV-2 variant viruses or after two-dose mRNA vaccination. Compared with two-dose vaccination, a three-dose vaccination course induces broad neutralizing antibody responses with improved durability against different SARS-CoV-2 variants, although neutralizing antibody titers against Omicron remain low. Intriguingly, among individuals with three-dose vaccination, Omicron breakthrough infection substantially augments serum neutralizing activity against a broad spectrum of SARS-CoV-2 variants, including Omicron variants BA.1, BA.2, and BA.5. Additionally, after Omicron breakthrough infection, memory T cells respond to the spike proteins of both ancestral and Omicron SARS-CoV-2 by producing cytokines with polyfunctionality. These results suggest that Omicron breakthrough infection following three-dose mRNA vaccination induces pan-SARS-CoV-2 immunity that may protect against emerging SARS-CoV-2 variants of concern.

Booster Vaccination Strategies for "Living With COVID-19".

Although the primary and secondary vaccination rates in Korea account for over 75% of the total population, confirmed cases of COVID-19 are dramatically increasing due to immune waning and the Omicron variant. Therefore, it is urgent to evaluate the effectiveness of booster vaccination strategies for living with COVID-19. In this work, we have developed an age-specific mathematical model with eight age groups and included age-specific comorbidities to evaluate the effectiveness of age-specific vaccination prioritization strategies to minimize morbidity and mortality. Furthermore, we have investigated the impacts of age-specific vaccination strategies for different vaccine supplies and non-pharmaceutical intervention levels during two periods: (1) when vaccine supply was insufficient and (2) after the emergence of the omicron variant. During the first period, the best option was to vaccinate the 30-49 year age group and the group with comorbidities to minimize morbidity and mortality, respectively. However, a booster vaccination should prioritize the 30-49 year age group to promote both minimal morbidity and mortality. Critical factors, such as vaccination speed, vaccine efficacy, and non-pharmaceutical interventions (NPIs), should be considered for effective vaccination prioritization as well. Primary, secondary vaccinations, and a booster shot vaccinations require different age prioritization strategies under different vaccination rates, vaccine efficacies, and NPI levels.

Differences in seroprevalence between epicenter and non-epicenter areas of the COVID-19 outbreak in South Korea.

To compare the standardized severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence of high epicenter region with non-epicenter region, serological studies were performed with a total of 3,268 sera from Daegu City and 3,981 sera from Chungbuk Province. Indirect immunofluorescence assay (IFA) for SARS-CoV-2 IgG results showed a high seroprevalence rate in the Daegu City (epicenter) compared with a non-epicenter area (Chungbuk Province) (1.27% vs. 0.91%, P = 0.0358). It is noteworthy that the highest seroprevalence in Daegu City was found in elderly patients (70's) whereas young adult patients (20's) in Chungbuk Province showed the highest seroprevalence. Neutralizing antibody (NAb) titers were found in three samples from Daegu City (3/3, 268, 0.09%) while none of the samples from Chungbuk Province were NAb positive. These results demonstrated that even following the large outbreak, the seropositive rate of SARS-CoV-2 in the general population remained low in South Korea.

Renin-angiotensin system modulators and other risk factors in COVID-19 patients with hypertension: a Korean perspective.

BACKGROUND: While hypertension is the most common comorbid condition in patients with coronavirus disease 2019 (COVID-19) in Korea, there is a lack of studies investigating risk factors in COVID-19 patients with hypertension in Korea. In this study, we aimed to examine the effects risk factors in hypertensive Korean COVID-19 patients. METHODS: We selected patients from the database of the project #OpenData4Covid19. This information was linked to their 3-year historical healthcare data. The severity of the disease was classified into five levels. We also clustered the levels into two grades. RESULTS: The risk factors associated with COVID-19 severity were old age, diabetes mellitus, cerebrovascular disease, chronic obstructive pulmonary disease (COPD), malignancy, and renal replacement therapy. The use of angiotensin converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) both before and after a diagnosis of COVID-19 were not associated with COVID-19 severity. A multivariate analysis revealed that old age, male sex, diabetes mellitus, and renal replacement therapy were risk factors for severe COVID-19. CONCLUSION: The results suggest that in hypertensive patients with COVID-19, older age, male sex, a diagnosis of diabetes mellitus, and renal replacement therapy were risk factors for a severe clinical course. In addition, the use of ARBs and ACEIs before or after COVID-19 infection did not affect a patient's risk of contracting COVID-19 nor did it contribute to a worse prognosis for the disease. These results highlighted that precautions should be considered for hypertensive patients with those risk factors and do not support discontinuation of ARBs and ACEIs during COVID-19 pandemic.

Viable SARS-CoV-2 in various specimens from COVID-19 patients.

OBJECTIVES: The aim was to determine whether various clinical specimens obtained from COVID-19 patients contain the infectious virus. METHODS: To demonstrate whether various clinical specimens contain the viable virus, we collected naso/oropharyngeal swabs and saliva, urine and stool samples from five COVID-19 patients and performed a quantitative polymerase chain reaction (qPCR) to assess viral load. Specimens positive with qPCR were subjected to virus isolation in Vero cells. We also used urine and stool samples to intranasally inoculate ferrets and evaluated the virus titres in nasal washes on 2, 4, 6 and 8 days post infection. RESULTS: SARS-CoV-2 RNA was detected in all naso/oropharyngeal swabs and saliva, urine and stool samples collected between days 8 and 30 of the clinical course. Notably, viral loads in urine, saliva and stool samples were almost equal to or higher than those in naso/oropharyngeal swabs (urine 1.08 ± 0.16-2.09 ± 0.85 log10 copies/mL, saliva 1.07 ± 0.34-1.65 ± 0.46 log10 copies/mL, stool 1.17 ± 0.32 log10 copies/mL, naso/oropharyngeal swabs 1.18 ± 0.12-1.34 ± 0.30 log10 copies/mL). Further, viable SARS-CoV-2 was isolated from naso/oropharyngeal swabs and saliva of COVID-19 patients, as well as nasal washes of ferrets inoculated with patient urine or stool. DISCUSSION: Viable SARS-CoV-2 was demonstrated in saliva, urine and stool samples from COVID-19 patients up to days 11-15 of the clinical course. This result suggests that viable SARS-CoV-2 can be secreted in various clinical samples and respiratory specimens.