Journal of clinical virology plus最新文献

Introduction

While the global COVID-19 pandemic is slowly coming under control, current efforts are focused on understanding the epidemiology of endemic SARS-CoV-2. The tool of choice for doing so remains serological tests that detect SARS-CoV-2 induced antibodies. However, the performance of these tests should be evaluated to ensure they comply with the specific performance criteria desired by each country that they are used in.

Methods

Here, we use pre-COVID-19 plasma and plasma from SARS-CoV-2-infected individuals collected in 2020, 2021 and 2022 to evaluate the performance of two commercial Rapid Lateral Flow (RLF) tests (the PANBIO™ COVID-19 IgG/IgM rapid test and the LABNOVATION™ COVID-19 (SARS-CoV-2) IgG/IgM rapid test) and one commercial ELISA test (the PLATELIA™ SARS-CoV-2 total Ab).

Results

We find that whereas the specificity of the two RLF tests is ≥ 95%, it was 91% for the ELISA tests. However, at 14 days post-COVID-19 date of diagnosis (DoD), only the ELISA test constantly achieved a sensitivity of ≥80% over all the three years. In addition, the rate of detection of the two RLF tests varied across the years with a sensitivity ranging from <80% in 2021 to >80% in 2022. More importantly the capacity of these two RLF tests to detect IgG antibodies decreased with time. On the contrary, the sensitivity of the ELISA test was still above 80% more than six months post DoD.

Conclusion

We recommend that sero-epidemiological surveys focused on testing antibodies should not rely on performances reported by the assay manufacturers. They should include a formal evaluation of the selected assays to ensure its limitations and strengths conform with the data-accuracy requirements of the surveys.

Asymptomatic and presymptomatic patients played a critical role in the maintenance and spread of infection during COVID pandemic. However, conflicting views about the infectiousness of asymptomatic patients have been raised.

Identification of asymptomatic cases relies on SARS-CoV-2 genome detection and, in the absence of common epidemiological variables, quantification of viral load (VL) has been proposed as an estimator for SARS-CoV-2 transmission.

Comparison of VLs from symptomatic and asymptomatic patients displayed variable results according to the studied population, the experimental design and the sampling, among other variables.

The aim of this work was to determine VLs in symptomatic and asymptomatic patients at the time of sampling and to retrospectively determine their relationship with severity of disease and other parameters that affected the course of COVID-19, in two towns located in Buenos Aires, Argentina.

Results from our study showed that VLs from symptomatic and asymptomatic patients were significantly different when analyzed globally. In addition, significant differences were found when VLs from each COVID-19 wave were analyzed. In the first wave VLs from asymptomatic patients (log10 8,21 gc/µl) were significantly higher than in symptomatic ones (log10 6,51 gc/µl) while; in the second wave, VLs from asymptomatic patients resulted significantly lower than in symptomatic patients (log10 4,51 gc/µl and log10 5,23 gc/µl, respectively). In the third wave, no significant differences were observed between VLs from both types of patients.

Results from this work demonstrated that the screening of both symptomatic and asymptomatic patients was of utmost importance in order to reduce SARS-CoV-2 transmission to communities.

Background

The neurological manifestations of acute SARS-CoV-2 infection are well established, but limited understanding of the post-infectious neurological complications of COVID-19 (PINCC) contributes to significant morbidity and mortality. Hence in this study, we aimed to describe the clinical, radiological, and electrophysiological spectrum and outcome of PINCC from a tertiary referral center.

Methods

We identified 18 cases with diverse neurological manifestations following recovery from an acute SARS-CoV-2 infection. The neurological manifestations, magnetic resonance imaging findings of the brain and spinal cord, nerve conduction studies, and the treatment and outcome data were collected from electronic medical records.

Results

The mean age of presentation was 47± 18.5 years, and 11 patients (61 %) were male. For 11 (61 %) patients, prior COVID-19 symptoms were minimal or absent. The mean time to onset of neurological manifestations was 3 weeks after COVID-19 infection (range 1–8 weeks). 14 patients (77.8 %) had central nervous system (CNS) manifestations, and 4 (22.2 %) had peripheral nervous system (PNS) manifestations. The CNS manifestations included cerebrovascular events in 7, demyelination in 4, and aseptic meningitis, amnestic mild cognitive impairment, and disseminated tuberculosis in one case each. PNS manifestations were Guillain-Barré syndrome, mononeuritis multiplex, asymmetric polyradiculoneuropathy, and isolated diaphragm palsy in one patient each.

Conclusion

Post-infectious neurological complications of COVID-19 can involve both central and peripheral nervous system and is independent of the severity of acute infection.

Introduction

Higher antibody levels, in particular antibodies directed against the receptor-binding domain (RBD) of the spike protein, protect against re-infection with SARS-CoV-2. Quantitative antibody response data provide insight into population immunity and are essential for decision-making on booster-vaccination strategies. We aimed to identify predictors for higher antibody responses such as gender, age, experienced COVID-19-compatible symptoms, disease severity and exposure to pre-determined risk factors associated with SARS-CoV-2 seropositivity.

Materials and methods

Quantitative anti-S-RBD responses were analysed in seropositive vaccine-naive individuals (n = 1,857) from a study population of 10,001 adults, including healthcare workers (n = 211) and individuals with a known date of a positive PCR (n = 214). Regression models tested associations between age, gender, the period of symptoms, disease severity, pre-identified exposure factors associated with SARS-CoV-2 seropositivity, and anti-S-RBD responses.

Results

Symptoms of more severe disease (fever and/or dyspnoea: OR 2.42 [95%CI 1.76–3.34], and hospital admission: OR 11.41 [95%CI 4.66–27.97]), and a longer interval between COVID-19-compatible symptoms and serum collection (OR 3.17 [95%CI 1.32–7.63]) were predictive for anti-S-RBD levels ≥300 U/mL. Working in healthcare was inversely associated with anti-S-RBD levels ≥300 U/mL (OR 0.51 [95%CI 0.31–0.82]). None of the pre-identified exposure factors associated with SARS-CoV-2 seropositivity could be identified as predictive of higher anti-S-RBD responses.

Conclusion

No exposure factors were identified as predictors of higher neutralising antibody responses. Nevertheless, higher neutralising antibody levels in individuals with more severe symptoms suggest better immunological protection against SARS-CoV-2 re-infection. In seroprevalence studies, that mainly include asymptomatic or mildly infected individuals, the determination of quantitative antibody responses may help in the interpretation of population immunity.

Background

Early evidence suggested that the impact of the COVID-19 pandemic was less severe in Africa compared to other parts of the world. However, more recent studies indicate higher SARS-CoV-2 infection and COVID-19 mortality rates on the continent than previously documented. Research is needed to better understand SARS-CoV-2 infection and immunity in Africa.

Methods

In early 2021, we studied the immune responses in healthcare workers (HCWs) at Lagos University Teaching Hospital (n = 134) and Oxford-AstraZeneca COVID-19 vaccine recipients from the general population (n = 116) across five local government areas (LGAs) in Lagos State, Nigeria. Western blots were used to simultaneously detect SARS-CoV-2 spike and nucleocapsid (N) antibodies (n = 250), and stimulation of peripheral blood mononuclear cells with N followed by an IFN-γ ELISA was used to examine T cell responses (n = 114).

Results

Antibody data demonstrated high SARS-CoV-2 seroprevalence of 72·4% (97/134) in HCWs and 60·3% (70/116) in the general population. Antibodies directed to only SARS-CoV-2 N, suggesting pre-existing coronavirus immunity, were seen in 9·7% (13/134) of HCWs and 15·5% (18/116) of the general population. T cell responses against SARS-CoV-2 N (n = 114) were robust in detecting exposure to the virus, demonstrating 87·5% sensitivity and 92·9% specificity in a subset of control samples tested. T cell responses against SARS-CoV-2 N were also observed in 83.3% of individuals with N-only antibodies, further suggesting that prior non-SARS-CoV-2 coronavirus infection may provide cellular immunity to SARS-CoV-2.

Conclusions

These results have important implications for understanding the paradoxically high SARS-CoV-2 infection with low mortality rate in Africa and supports the need to better understand the implications of SARS-CoV-2 cellular immunity.

Background

Saliva has been considered a suitable sample material for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA testing, but uncertainty remained regarding sensitivity and reliability of different saliva collection methods.

Objectives

This study aimed to investigate the potential utility of expectorated saliva (ES) and drooled saliva (DS) for community mass testing.

Study design

Self-collected ES and DS samples were obtained in a prospective cohort study with 2,878 participants. The utility of saliva for SARS-CoV-2 qRT-PCR testing was assessed by comparing the capacity to detect SARS-CoV-2 positive cases with results for self-collected combined throat and nose (CTN) swabs. Additionally, quantification cycle (Cq) values were compared.

Results

ES- and DS-based tests showed the same high level of concordance (98% vs 98%) with CTN swab-based results. Sensitivity was higher for DS (94%) than for ES (83%) or CTN swab (90%) but differences were statistically not significant. Comparing only symptomatic cases, however, a significantly higher sensitivity of DS (96%) than of ES (76%) or CTN swab (91%) was observed. Cq values of saliva and swab specimen were significantly correlated and appeared to be not impacted by age or other potentially confounding factors.

Conclusions

Saliva-based SARS-CoV-2 RNA testing showed high diagnostic accuracy and can be considered an alternative where swabbing may not be tolerated or operationally feasible. DS yielded the same or better diagnostic performance compared to ES and may present a preferred option with reduced aerosol risk and increased compliance.

Objective

To investigate whether SARS-CoV-2 omicron breakthrough infection in individuals after three doses of wildtype-based BNT162b2 increases antibody levels measured by a commercially available wildtype-based immunoassay.

Methods

16 of 21 individuals in a BNT162b2 vaccination cohort (recruited 129 [129–135] days after dose 3) experienced a breakthrough infection (BTI) between March and September 2022. Antibodies to the receptor binding domain (RBP) of the spike protein (Anti-S) were quantified using the wildtype-based Elecsys SARS-CoV-2 S assay (Roche). Antibody responses of triple vaccinated BTI cases were compared to triple vaccinated individuals without breakthrough infection and to 16 matched individuals after primary omicron infection.

Results

In the 16 individuals with primary Omicron infection, the anti-S assay returned only very low results (2.25 [0.61–5.80] U/mL). However, in individuals with BTI, Anti-S levels rose from 7,135 [5,870–17,470] U/mL to 21,705 (7,750–46,137.5) U/mL. At the same time, Anti-S concentrations decreased from 9,120 [7,480–13,480] U/mL to 3,830 (2,390–4,220) U/mL in those 5 of 21 vaccinated only.

Conclusions

Our data suggest that breakthrough infection with omicron can efficiently boost wild-type antibodies in individuals vaccinated with wild-type BNT162b2.

Background

The role of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) neutralizing antibody response from natural infection and vaccination, and the potential determinants of this response are poorly understood. Characterizing this antibody response and the factors associated with neutralization can help inform future prevention efforts and improve clinical outcomes in those infected.

Objectives

The goals of this study were to prospectively evaluate SARS-CoV-2 antibody levels and the neutralizing antibody responses among naturally infected adults and to determine demographic and behavioral factors independently associated with these responses.

Methods

Serum was collected from seropositive individuals at baseline, four-weeks, and three-months following their first study visit to be evaluated for antibody levels. Detection of neutralizing antibodies was performed at baseline. Participant demographic and behavioral information was collected via web questionnaire prior to their first visit.

Results

At baseline, higher antibody levels were associated with better neutralization capacity, with 83% of participants having detectable neutralizing antibodies. We found an age-dependent effect on antibody level and neutralization capacity with participants over 65 years having significantly higher levels. Ethnicity, heart disease, autoimmune disease, and COVID symptoms were associated with higher antibody levels, but not with increased neutralization capacity. Work environment during the pandemic correlated with increased neutralization capacity, while kidney or liver disease and traveling out of state after February 2020 correlated with decreased neutralization capacity, however neither correlated with antibody levels.

Conclusions

Our data show that natural infection by SARS-CoV-2 can induce a humoral response reflected by high antibody levels and neutralization capacity.