Detection and viral RNA shedding of SARS-CoV-2 in respiratory specimens relative to symptom onset among COVID-19 patients in Bavaria, Germany

Vaccine-hesitant individuals accumulate additional COVID-19 risk due to divergent perception and behaviors related to SARS-CoV-2 testing: a population-based, cross-sectional study

Purpose

To investigate the perception of SARS-CoV-2 detection methods, information sources, and opinions on appropriate behavior after receiving negative or positive test results.

Methods

In a questionnaire-based, cross-sectional study conducted between September 1 and November 17, 2021, epidemiological, behavioral, and COVID-19-related data were acquired from the public in Munich, Germany.

Results

Most of the 1388 participants obtained information from online media (82.8%) as well as state and federal authorities (80.3%). 93.4% believed in the accuracy of SARS-CoV-2 PCR testing and 41.2% in the accuracy of rapid antigen tests (RATs). However, RATs were preferred for testing (59.1%) over PCR (51.1%). 24.0% of all individuals were willing to ignore hygiene measures and 76.9% were less afraid of SARS-CoV-2 transmission after receiving a negative PCR test (5.9% and 48.8% in case of a negative RAT). 28.8% reported not to self-isolate after receiving a positive RAT. Multivariate analyses revealed that non-vaccinated individuals relied less on information from governmental authorities (p = 0.0004) and more on social media (p = 0.0216), disbelieved in the accuracy of the PCR test (p ≤ 0.0001) while displaying strong preference towards using RATs (p ≤ 0.0001), were more willing to abandon pandemic-related hygiene measures (p ≤ 0.0001), less afraid of transmitting SARS-CoV-2 after a negative RAT (p ≤ 0.0001), and less likely to isolate after a positive RAT (p ≤ 0.0001).

Conclusion

Insights into preferred information sources as well as perception, preferences, and behavior related to SARS-CoV-2 testing and hygiene measures are key to refining public health information and surveillance campaigns. Non-vaccinated individuals’ divergent believes and behaviors possibly increase their COVID-19 risk.

Supplementary Information

The online version contains supplementary material available at 10.1007/s15010-022-01947-z .

A fast extraction-free isothermal LAMP assay for detection of SARS-CoV-2 with potential use in resource-limited settings

Background

To retain the spread of SARS-CoV-2, fast, sensitive and cost-effective testing is essential, particularly in resource limited settings (RLS). Current standard nucleic acid-based RT-PCR assays, although highly sensitive and specific, require transportation of samples to specialised laboratories, trained staff and expensive reagents. The latter are often not readily available in low- and middle-income countries and this may significantly impact on the successful disease management in these settings. Various studies have suggested a SARS-CoV-2 loop mediated isothermal amplification (LAMP) assay as an alternative method to RT-PCR.

Methods

Four previously published primer pairs were used for detection of SARS-CoV-2 in the LAMP assay. To determine optimal conditions, different temperatures, sample input and incubation times were tested. Ninety-three extracted RNA samples from St. George's Hospital, London, 10 non-extracted nasopharyngeal swab samples from Great Ormond Street Hospital for Children, London, and 92 non-extracted samples from Queen Elisabeth Central Hospital (QECH), Malawi, which have previously been tested for SARS-Cov-2 by quantitative reverse-transcription RealTime PCR (qRT-PCR), were analysed in the LAMP assay.

Results

In this study we report the optimisation of an extraction-free colourimetric SARS-CoV-2 LAMP assay and demonstrated that a lower limit of detection (LOD) between 10 and 100 copies/µL of SARS-CoV-2 could be readily detected by a colour change of the reaction within as little as 30 min. We further show that this assay could be quickly established in Malawi, as no expensive equipment is necessary. We tested 92 clinical samples from QECH and showed the sensitivity and specificity of the assay to be 86.7% and 98.4%, respectively. Some viral transport media, used routinely to stabilise RNA in clinical samples during transportation, caused a non-specific colour-change in the LAMP reaction and therefore we suggest collecting samples in phosphate buffered saline (which did not affect the colour) as the assay allows immediate sample analysis on-site.

Conclusion

SARS-CoV-2 LAMP is a cheap and reliable assay that can be readily employed in RLS to improve disease monitoring and management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-022-01800-7.

SARS-CoV-2 viral clearance and viral load kinetics in young children (1-6 years) compared to adults: Results of a longitudinal study in Germany

OBJECTIVE

To investigate SARS-COV-2 viral clearance and viral load kinetics in the course of infection in children aged 1-6 years in comparison with adults.

METHODS

Prospective cohort study of infected daycare children and staff and their close contacts in households from 11/2020 to 06/2021. Adult participants took upper respiratory tract specimen from themselves and/or their children, for PCR tests on SARS-CoV-2. Data on symptoms and exposure were used to determine the date of probable infection for each participant. We determined (a) viral clearance, and (b) viral load dynamics over time. Samples were taken from day 4-6 to day 16-18 after diagnosis of the index case in the respective daycare group (5 samples per participant).

RESULTS

We included 40 children (1-6 years) and 67 adults (18-77 years) with SARS-CoV-2 infection. Samples were available at a mean of 4.3 points of time per participant. Among the participants, the 12-day study period fell in different periods within the individual course of infection, ranging from day 5-17 to day 15-26 after assumed infection.Children reached viral clearance at a median of 20 days after assumed infection (95% CI 17-21 days, Kaplan-Meier Analysis), adults at 23 days (95% CI 20-25 days, difference not significant). In both children and adults, viral load decreased over time with trajectories of the mean viral load not being statistically different between groups. Kaplan-Meier calculations show that from day 15 (95% CI 13-15), 50% of all participants had a viral load <1 million copies/ml, i.e. were no longer infectious or negative.

CONCLUSION

Children aged 1-6 and adults infected with SARS-CoV-2 (wild type and Alpha variant) did not differ significantly in terms of viral load kinetics and time needed to clear the virus. Therefore, containment measures are important also in the daycare settings as long as the pandemic continues.