Prevention and Control of Porcine Epidemic Diarrhea: The Development of Recombination-Resistant Live Attenuated Vaccines.

Porcine epidemic diarrhea (PED), causing up to 100% mortality in neonatal pigs, is a highly contagious enteric disease caused by PED virus (PEDV). The highly virulent genogroup 2 (G2) PEDV emerged in 2010 and has caused huge economic losses to the pork industry globally. It was first reported in the US in 2013, caused country-wide outbreaks, and posed tremendous hardship for many pork producers in 2013-2014. Vaccination of pregnant sows/gilts with live attenuated vaccines (LAVs) is the most effective strategy to induce lactogenic immunity in the sows/gilts and provide a passive protection via the colostrum and milk to suckling piglets against PED. However, there are still no safe and effective vaccines available after about one decade of endeavor. One of the biggest concerns is the potential reversion to virulence of an LAV in the field. In this review, we summarize the status and the major obstacles in PEDV LAV development. We also discuss the function of the transcriptional regulatory sequences in PEDV transcription, contributing to recombination, and possible strategies to prevent the reversion of LAVs. This article provides insights into the rational design of a promising LAV without safety issues.

COVID-19 mRNA Vaccines Are Generally Safe in the Short Term: A Vaccine Vigilance Real-World Study Says.

Background: The prophylactic vaccination of COVID-19 mRNA vaccines is the first large-scale application of this kind in the human world. Over 1.8 million doses of the COVID-19 vaccine had been administered in the US until December 2020, and around 0.2% submitted AE reports to the Vaccine Adverse Event Reporting System (VAERS). This study aimed to evaluate the AEs following immunization (AEFIs) and analyze the potential associations based on the information from the VAERS database. Methods: We searched the VAERS database recorded AEFIs after COVID-19 vaccines in December 2020. After data mapping, we summarized demographic and clinical features of reported cases. Fisher exact test was used to comparing the clinical characteristics among AE groups with an anaphylactic response, concerning neurological disorders and death. Results: VAERS reported 3,908 AEFIs of COVID-19 vaccines in December 2020. Most (79.68%) were reported after the first dose of the vaccine. Among the reported cases, we found that general disorders (48.80%), nervous system disorders (46.39%), and gastrointestinal disorders (25.54%) were the most common AEFIs. The allergy history was more frequent in vaccine recipients with anaphylactic reactions than those without (64.91% vs. 49.62%, OR = 1.88, P <0.017). History of anxiety or depression was more common in subjects reporting severe neurological AEFIs than those reporting other AEFIs (18.37% vs. 7.85%, OR = 2.64, P <0.017). Cases reporting death were significantly older (79.36 ± 10.41-year-old vs. 42.64 ± 12.55-year-old, P <0.01, 95% CI 29.30-44.15) and more likely experienced hypertension (50.00% vs. 11.42%, OR = 7.76, P <0.01) and neurological disorders (50.00% vs. 5.36%, OR = 17.65, P <0.01) than other vaccine recipients. The outpatient and emergency room visit rates were 11.92 and 22.42% for AEFIs, and 2.53% of cases needed hospitalization. Conclusion: AEFIs of COVID-19 mRNA vaccines were generally non-severe local or systemic reactions. A prior allergy history is the risk factor for anaphylaxis, while a history of anxiety may link with severe neurological AEs. Such vaccine recipients need further evaluation and monitor.