SARS-CoV-2 Infectivity and Antibody Titer Reduction for 6 Months After Second Dose of BNT162b2 mRNA Vaccine in Health Care Workers: A Prospective Cohort Study.

Several studies reported that severe acute respiratory syndrome coronavirus-2 antibody levels change over 6 months in participants receiving the vaccination. From the enrolled 272 health care workers (HCWs), blood samples were obtained at 2, 16, and 24 weeks after the second vaccination dose. In the 267 noninfected HCWs, the neutralizing antibodies decreased by 23.9%, and the anti-spike/receptor binding domain antibody decreased by 53.8% at 24 weeks. We observed no significant difference in antibody reduction between the sexes; however, in younger individuals, there was higher antibody formation and lower reduction rates of the neutralizing antibody. In 3 HCWs with breakthrough infections, the antibody levels were relatively low just before the coronavirus disease 2019 infection. In conclusion, as antibody titers decrease over time after the second vaccination dose and HCWs with low antibody titers tend to have a high probability of breakthrough infection, an additional dose should be considered after several months. Blood samples were obtained from health care workers at 2, 16, and 24 weeks after a second vaccination dose. Antibody titers decreased over time and the participants with low antibody titers tended to have a high probability of breakthrough infection.

Strong SARS-CoV-2 Antibody Response After Booster Dose of BNT162b2 mRNA Vaccines in Uninfected Healthcare Workers.

Despite strict guidelines for coronavirus disease 2019 (COVID-19), South Korea is facing its fourth pandemic wave. In this study, by using an automated electrochemiluminescence immunoassay assay, we tracked anti-spike protein receptor-binding domain (anti-S-RBD) antibody titer from the second dose to 2 weeks after the booster dose vaccination. After the second dose, 234 participants had their anti-S-RBD antibody titers decrease over time. We also showed the booster dose (the third dose) increased antibody titer by average 14 (min-max, 2-255)-fold higher compared to the second dose among the 211-booster group participants, therefore, the booster dose could be recommended for low responders to the second dose. Our findings showed a distinct humoral response after booster doses of BNT162b2 mRNA vaccines and may provide further evidence of booster vaccination efficacy. These data will also be helpful in vaccination policy decisions that determine the need for the booster dose.

Evaluation of Three Multiplex Real-time Reverse Transcription PCR Assays for Simultaneous Detection of SARS-CoV-2, Influenza A/B, and Respiratory Syncytial Virus in Nasopharyngeal Swabs.

BACKGROUND: In the coronavirus disease 2019 (COVID-19) pandemic era, the simultaneous detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza virus (Flu), and respiratory syncytial virus (RSV) is important in the rapid differential diagnosis in patients with respiratory symptoms. Three multiplex real-time reverse transcription polymerase chain reaction (rRT-PCR) assays have been recently developed commercially in Korea: PowerChek™ SARS-CoV-2, Influenza A&B Multiplex Real-time PCR Kit (PowerChek; KogeneBiotech); STANDARD™ M Flu/SARS-CoV-2 Real-time Detection Kit (STANDARD M; SD BioSensor); and Allplex™ SARS-CoV-2/FluA/FluB/RSV Assay (Allplex; Seegene). We evaluated the analytical and clinical performances of these kits. METHODS: A limit of detection tests were performed and cross-reactivity analysis was executed using clinical respiratory samples. Ninety-seven SARS-CoV-2-positive, 201 SARS-CoV-2-negative, 71 influenza A-positive, 50 influenza B-positive, 78 RSV-positive, and 207 other respiratory virus-positive nasopharyngeal swabs were tested using the three assays. The AdvanSure™ respiratory viruses rRT-PCR assay (AdvanSure; LG Life Sciences) was used as a comparator assay for RSV. RESULTS: Except in influenza B, in SARS-CoV-2 and influenza A, there were no significant differences in detecting specific genes of the viruses among the three assays. All three kits did not cross-react with common respiratory viruses. All three kits had greater than 92% positive percent agreement and negative percent agreement and ≥ 0.95 kappa value in the detection of SARS-CoV-2 and flu A/B. Allplex detected RSV more sensitively than AdvanSure. CONCLUSION: The overall performance of three multiplex rRT-PCR assays for the concurrent detection of SARS-CoV-2, influenza A/B, and RSV was comparable. These kits will promote prompt differential diagnosis of COVID-19, influenza, and RSV infection in the COVID-19 pandemic era.

Performance evaluation of three automated quantitative immunoassays and their correlation with a surrogate virus neutralization test in coronavirus disease 19 patients and pre-pandemic controls.

BACKGROUND: SARS-CoV-2 pandemic is currently ongoing, meanwhile vaccinations are rapidly underway in some countries. The quantitative immunoassays detecting antibodies against spike antigen of SARS-CoV-2 have been developed based on the findings that they have a better correlation with the neutralizing antibody. METHODS: The performances of the Abbott Architect SARS-CoV-2 IgG II Quant, DiaSorin LIAISON SARS-CoV-2 TrimericS IgG, and Roche Elecsys anti-SARS-CoV-2 S were evaluated on 173 sera from 126 SARS-CoV-2 patients and 151 pre-pandemic sera. Their correlations with GenScript cPass SARS-CoV-2 Neutralization Antibody Detection Kit were also analyzed on 173 sera from 126 SARS-CoV-2 patients. RESULTS: Architect SARS-CoV-2 IgG II Quant and Elecsys anti-SARS-CoV-2 S showed the highest overall sensitivity (96.0%), followed by LIAISON SARS-CoV-2 TrimericS IgG (93.6%). The specificities of Elecsys anti-SARS-CoV-2 S and LIAISON SARS-CoV-2 TrimericS IgG were 100.0%, followed by Architect SARS-CoV-2 IgG II Quant (99.3%). Regarding the correlation with cPass neutralization antibody assay, LIAISON SARS-CoV-2 TrimericS IgG showed the best correlation (Spearman rho = 0.88), followed by Architect SARS-CoV-2 IgG II Quant and Elecsys anti-SARS-CoV-2 S (all rho = 0.87). CONCLUSIONS: The three automated quantitative immunoassays showed good diagnostic performance and strong correlations with neutralization antibodies. These assays will be useful in diagnostic assistance, evaluating the response to vaccination, and the assessment of herd immunity in the future.

Positivity of SARS-CoV-2 Antibodies among Korean Healthy Healthcare Workers 1 and 2 Weeks after Second Dose of Pfizer-BioNTech Vaccination.

The antibody titer of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was observed in 289 healthy healthcare workers who had completed the second dose of the Pfizer-BioNTech coronavirus disease 2019 (COVID-19) vaccine. Antibody tests were performed using both the automated electrochemiluminescence immunoassay (ECLIA) and the chromatographic lateral flow immunoassay (LFIA). All subjects had antibodies against the receptor binding domain of the spike protein of SARS-CoV-2 only one week after completing the vaccination, and the antibody titer became significantly higher after another week (P < 0.001). Since there was a large amount of antibody formation within two weeks after completion of vaccination, the less sensitive method, LFIA, also showed high sensitivity. There was no significant difference between whole blood and serum in detecting SARS-CoV-2 antibodies after vaccination. This is an early study of vaccinations among Koreans and is expected to contribute to the establishment of national guidelines on COVID-19 vaccination.

Effects of Storage Temperature and Media/Buffer for SARS-CoV-2 Nucleic Acid Detection.

OBJECTIVES: The increase in the number of patients with coronavirus disease 2019 (COVID-19) has delayed real-time reverse transcription-quantitative polymerase chain reaction (RT-qPCR), requiring proper shipping and storage conditions, especially in hot weather. This study aims to assess how some conditions, such as storage period, temperature, media or buffer, and sample types, affect the results of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RT-qPCR. METHODS: SARS-CoV-2-positive specimens were collected from Boramae Medical Center for 2 months (from May to June 2020) and stored in different media or buffers at different temperatures. RESULTS: As a result of examining confirmed patient samples, RT-qPCR results were not significantly affected by 2°C to 8°C storage until after 7 days. When stored at 20°C to 22°C or above 35°C, the results were affected negatively even after 1 day. Higher storage temperatures resulted in a lower probability of detecting viral nucleic acids because of degradation. Samples stored in pH-controlled media or buffer were more stable than those stored in nonbuffer states. CONCLUSIONS: These results emphasize the importance of storage temperature and media or buffer and performing RT-qPCR for SARS-CoV-2 nucleic acid detection as soon as possible after sample collection.