To rapidly identify individuals infected with severe acute respiratory syndrome coronavirus‐2 (SARS‐CoV‐2) and control the spread of coronavirus disease (COVID‐19), there is an urgent need for highly sensitive on‐site virus detection methods. A clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR‐associated protein (Cas)‐based molecular diagnostic method was developed for this purpose. Here, a CRISPR system‐mediated lateral flow assay (LFA) for SARS‐CoV‐2 was established based on multienzyme isothermal rapid amplification, CRISPR‐Cas13a nuclease, and LFA. To improve the limit of detection (LoD), the crispr RNA, amplification primer, and probe were screened, in addition to concentrations of various components in the reaction system. The LoD of CRISPR detection was improved to 0.25 copy/μl in both fluorescence‐ and immunochromatography‐based assays. To enhance the quality control of the CRISPR‐based LFA method, glyceraldehyde‐3‐phosphate dehydrogenase was detected as a reference using a triple‐line strip design in a lateral flow strip. In total, 52 COVID‐19‐positive and 101 COVID‐19‐negative clinical samples examined by reverse transcription polymerase chain reaction (RT‐PCR) were tested using the CRISPR immunochromatographic detection technique. Results revealed 100% consistency, indicating the comparable effectiveness of our method to that of RT‐PCR. In conclusion, this approach significantly improves the sensitivity and reliability of CRISPR‐mediated LFA and provides a crucial tool for on‐site detection of SARS‐CoV‐2.

Although numerous COVID-19 vaccines are effective against COVID-19 infection and variants of concern (VOC) in the real world, it is imperative to obtain evidence of the corresponding vaccine effectiveness (VE). This study estimates the real-world effectiveness of the BNT162b2 and mRNA-1273 vaccines against COVID-19 infection and determines the influence of different virus variants on VE by using test-negative design (TND) studies. We systematically searched for published articles on the efficacy of BNT162b2 and mRNA-1273 against COVID-19 infection. Two researchers independently selected and extracted data from eligible studies. We calculated the VE associated with different vaccine types, SARS-CoV-2 variants, and vaccination statuses, using an inverse variance random-effects model. We selected 19 eligible studies in the meta-analysis from 1651 records. For the partially vaccinated group, the VE of BNT162b2 and mRNA-1273 was 61% and 78% against COVID-19 infection, respectively. For the completely vaccinated group, the VE of BNT162b2 and mRNA-1273 was 90% and 92% against COVID-19 infection, respectively. During subgroup analyses, the overall VE of BNT162b2 and mRNA-1273 against the Delta variant was 53% and 71%, respectively, for the partially vaccinated group; the respective VE values were 85% and 91% for the fully vaccinated group. Irrespective of the BNT162b2 or mRNA-1273 vaccines, the Delta variant significantly weakened vaccine protection for the partially vaccinated group, while full vaccination was highly effective against COVID-19 infection and various VOC. The mRNA-1273 vaccine is more effective against COVID-19 infection and VOC than the BNT162b2 vaccine, especially for the partially vaccinated group. Overall, the results provide recommendations for national and regional vaccine policies.

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Background Food allergy has been a significant public health issue with growing severity, prevalence and limited treatments. The neutrophil-activating protein A subunit (NapA) of Helicobacter pylori, a Th1-activating immune modulator, has been shown to have therapeutic potential in allergic diseases. Objective We adopted Lactococcus lactis (L. lactis) as mucosal delivery vehicles of NapA and sought to determine the regulatory effect of recombinant bacterium (L. lactis NZ3900/pNZ8149-NapA) on food allergy in mice. Methods The NapA expression efficiency of recombinant bacterium were determined. The effects of recombinant bacterium on food allergy in Balb/c mice were also investigated. Results NapA were delivered and expressed efficiently via L. lactis. The intervention of the engineered bacterium ameliorated food allergy symptoms (acute diarrhea and intestinal inflammation) and decreased serum histamine levels. In addition, the secretion of OVA-specific IgG2a, IFN-γ was promoted and the level of IL-4, OVA-specific IgE was restrained. Conclusions The recombinant strain may attenuate food allergy in mice through immune regulatory effect. Thus, L. lactis NZ3900/pNZ8149-NapA may be a promising approach for preventing or treating food allergy.