Development and application of N-protein blocking ELISA for detecting porcine epidemic diarrhea virus antibodies

The purpose of this study is to establish a blocking ELISA antibodies detection method for porcine epidemic diarrhea virus (PEDV). The purified N protein was used as the coating antigen, and the ELISA reaction conditions were optimized by the chess rboard titration. A blocking ELISA method for detecting PEDV antibodies was established, and its specificity, sensitivity and repeatability tests were carried out. One hundred and forty clinical serum samples were tested, and the results were compared with commercially IDvet PEDV indirect ELISA antibodies detection kit. The results showed that the best antigen coating concentration was 625 ng.mL-1, and the best dilution ratio of serum was 1:1;The best dilution of the HRP-conjugated antibody working solution was 1:5 000;There was no cross-reaction with healthy pig serum and the positive sera of common pig disease pathogens, such as classical swine fever virus (CSFV), porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus type 2 (PCV2), and transmissible gastroenteritis virus (TGEV). The sensitivity of PEDV positive serum was 1:16, which was equivalent to that of IDvet ELISA kit (titer 1:32). The coefficient of variation of within-run and between-run repeatability test is less than 10%, so it showed that the blocking ELISA established in this study had good repeatability and stability;the kappa value of detected 140 clinical porcine serum using this method was 0.87 when compared with IDvet ELISA. The above results indicated that the established blocking ELISA method for detecting PEDV antibodies in this study could be applied to the prevention and control of PEDV, epidemiological investigation and the monitoring of antibody levels after vaccine immunization.

Bell's palsy after inactivated COVID-19 vaccination in a patient with history of recurrent Bell's palsy: A case report.

BACKGROUND: With rapid and extensive administration of inactivated coronavirus disease 2019 (COVID-19) vaccine to the general population in China, it is crucial for clinicians to recognize neurological complications or other side effects associated with COVID-19 vaccination. CASE SUMMARY: Here we report the first case of Bell's palsy after the first dose of inactivated COVID-19 vaccine in China. The patient was a 36-year-old woman with a past history of Bell's palsy. Two days after receiving the first dose of the Sinovac Life Sciences inactivated COVID-19 vaccine, the patient developed right-side Bell's palsy and binoculus keratoconjunctivitis. Prednisone, artificial tears and fluorometholone eye drops were applied. The patient's symptoms began to improve by day 7 and resolved by day 54. CONCLUSION: As mRNA COVID-19 vaccine trials reported cases of Bell's palsy as adverse events, we should pay attention to the occurrence of Bell's palsy after inactivated COVID-19 vaccination. A history of Bell's palsy, rapid increase of immunoglobulin M and immunoglobin G-specific antibodies to severe acute respiratory syndrome coronavirus 2 may be risk factors for Bell's palsy after COVID-19 vaccination.

Mental health and preventive behaviour of pregnant women in China during the early phase of the COVID-19 period.

BACKGROUND: The COVID-19 has caused significant toll over the globe. Pregnant women are at risk of infection. The present study examined the frequency of washing hands with soap and wearing face mask when going out, prevalence of depression and anxiety, and identified their associated factors among pregnant women during the early phase of COVID-19 outbreak in China. METHODS: A cross-sectional online survey was conducted between 24 February and 3 March 2020. A total of 15 428 pregnant women who were using maternal health care services in China completed a questionnaire which assessed their socio-demographic and pregnancy-related characteristics, contextual, cognitive and social factors related to COVID-19, frequency of washing hands and wearing face masks, and depression and anxiety. Logistics regression analyses were performed to identify the associated factors of preventive behaviours and mental health. RESULTS: The prevalence of probable anxiety and depression was 28.2% and 43.6% respectively. 19.8% reported always wearing face mask when going out, and 19.1% reported washing hands with soap for more than 10 times per day. Results from logistic regression analyses showed that older age was associated with lower levels of depression and anxiety (OR = 0.42-0.67) and higher frequency of washing hands (OR = 1.57-3.40). Higher level of education level was associated with probable depression (OR = 1.31-1.45) and higher frequency of wearing face mask (OR = 1.50-1.57). After adjusting for significant socio-demographic and pregnancy-related factors, place of residence being locked down (aOR = 1.10-1.11), being quarantined (aOR = 1.42-1.57), personally knowing someone being infected with COVID-19 (aOR = 1.80-1.92), perception that COVID-19 would pose long term physical harm to human (aOR = 1.25-1.28) were associated with higher levels of depression and anxiety, while the perception that the disease will be under control in the coming month was associated with lower levels of depression and anxiety (aOR = 0.59-0.63) and lower tendency of always wearing face mask (aOR = 0.85). Social support was associated with lower levels of depression and anxiety (aOR = 0.86-0,87) and higher frequency of washing hands (aOR = 1.06). CONCLUSIONS: The mental health and preventive behaviours of pregnant women during COVID-19 outbreak was associated with a range of socio-demographic, pregnancy-related, contextual, cognitive and social factors. Interventions to mitigate their mental health problems and to promote preventive behaviours are highly warranted.

Application of an optimized pharyngeal swab-assisted device in pharyngeal sampling for COVID-19 patients.

BACKGROUND: Coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has triggered a global pandemic. Healthcare workers are placed at an elevated risk of nosocomial cross-infection from clinical exposure. One diagnostic criterion for COVID-19 is a positive result from a real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) assay of pharyngeal swab specimens, which has been a routine procedure for healthcare workers during the outbreak. In the context of a global shortage of personal protective equipment (PPE), we aimed to lower the probability of clinical cross-infection without impacting the results of pharynx sampling through an optimized pharyngeal swab assisted device (OPAD). METHODS: To evaluate the efficacy and feasibility of an OPAD for the detection of SARS-CoV-2, 22 confirmed COVID-19 cases were enrolled in our self-controlled study. The results of two pharyngeal sampling qRT-PCR tests using the OPAD or the traditional method were recorded each. Clinical data including baseline characteristics, laboratory tests, and computed tomography (CT) results were also collected. The procedure duration and levels of pharynx exposure with the OPAD, and the diagnostic consistency between the OPAD and the traditional method for pharyngeal sampling qRT-PCR, were evaluated individually. Additionally, a questionnaire was designed for healthcare workers who had performed the pharyngeal swab to deepen our understanding of their attitude during their service on the frontline. RESULTS: In all 44 samplings (22 samples with each method), the qRT-PCR results of 18 pairs (81.82%) were consistent, while 3 (13.64%) were single positive with the OPAD. The positive rate was slightly higher with the OPAD (54.55%, 12/22) than with the traditional method (45.45%, 10/22). Using the OPAD, the average procedure duration of sampling was 30 s (30±13 s). Pharynx exposure was excellent in 21 subjects (95.45%, 21/22), which meant that the operator could acquire the swabs without difficulty. CONCLUSIONS: As the COVID-19 pandemic escalates, our OPAD has identical efficacy compared to the traditional method for pharyngeal swabs, and it can also contribute to protecting the safety of healthcare workers.

The accuracy of healthcare worker versus self collected (2-in-1) Oropharyngeal and Bilateral Mid-Turbinate (OPMT) swabs and saliva samples for SARS-CoV-2.

BACKGROUND: Self-sampling for SARS-CoV-2 would significantly raise testing capacity and reduce healthcare worker (HCW) exposure to infectious droplets personal, and protective equipment (PPE) use. METHODS: We conducted a diagnostic accuracy study where subjects with a confirmed diagnosis of COVID-19 (n = 401) and healthy volunteers (n = 100) were asked to self-swab from their oropharynx and mid-turbinate (OPMT), and self-collect saliva. The results of these samples were compared to an OPMT performed by a HCW in the same patient at the same session. RESULTS: In subjects confirmed to have COVID-19, the sensitivities of the HCW-swab, self-swab, saliva, and combined self-swab plus saliva samples were 82.8%, 75.1%, 74.3% and 86.5% respectively. All samples obtained from healthy volunteers were tested negative. Compared to HCW-swab, the sensitivities of a self-swab sample and saliva sample were inferior by 8.7% (95%CI: 2.4% to 15.0%, p = 0.006) and 9.5% (95%CI: 3.1% to 15.8%, p = 0.003) respectively. The combined detection rate of self-swab and saliva had a sensitivity of 2.7% (95%CI: -2.6% to 8.0%, p = 0.321). The sensitivity of both the self-collection methods are higher when the Ct value of the HCW swab is less than 30. The specificity of both the self-swab and saliva testing was 100% (95% CI 96.4% to 100%). CONCLUSION: Our study provides evidence that sensitivities of self-collected OPMT swab and saliva samples were inferior to a HCW swab, but they could still be useful testing tools in the appropriate clinical settings.

The Accuracy of Healthcare Worker versus Self Collected (2-in-1) Oropharyngeal and Bilateral Mid-Turbinate (OPMT) Swabs and Saliva Samples for SARS-CoV-2 (preprint)

Background Self-sampling for SARS-CoV-2 would significantly raise testing capacity and reduce healthcare worker (HCW) exposure to infectious droplets personal, and protective equipment (PPE) use. Methods We conducted a diagnostic accuracy study where subjects with a confirmed diagnosis of COVID-19 (n=401) and healthy volunteers (n=100) were asked to self-swab from their oropharynx and mid-turbinate (OPMT), and self-collect saliva. The results of these samples were compared to an OPMT performed by a HCW in the same patient at the same session. Results In subjects confirmed to have COVID-19, the detection rates of the HCW-swab, self-swab, saliva, and combined self-swab plus saliva samples were 82.8%, 75.1%, 74.3% and 86.5% respectively. All samples obtained from healthy volunteers were tested negative. Compared to HCW-swab, the detection rates of a self-swab sample and saliva sample were inferior by 8.7% (95%CI: 2.4% to 15.0%, p=0.006) and 9.5% (95%CI: 3.1% to 15.8%, p=0.003) respectively. The combined detection rate of self-swab and saliva had a higher detection rate of 2.7% (95%CI: -2.6% to 8.0%, p=0.321). The sensitivity of both the self-collection methods are higher when the Ct value of the HCW swab is less than 30. The negative correctness of both the self-swab and saliva testing was 100% (95% CI 96.4% to 100%). Conclusion Our study provides evidence that detection rates of self-collected OPMT swab and saliva samples were inferior to a HCW swab, but they could still be useful testing tools in the appropriate clinical settings.