ABSTRACT
This is a comprehensive review based on the published papers in the field of COVID-19 vaccines and vaccination. Many efforts have been made to develop vaccines to combat this pandemic. Since December 2020, more than 200 vaccines have been tested in various research stages and in clinical trials on humans, of which eight vaccines reached phase four clinical trials in humans and approved by FDA and EUA. After the Pfizer-BioNTech vaccine that had the highest efficacy (95%), the efficacy of the other vaccines are as follows: Moderna 94.5%, Sputnik V 91%, Novavax 89.7%, Sinopharm 79.3%, Oxford/AstraZenaca 70.4%, Johnson and Johnson 66.9%, and Sinovac 50.7%. At present, protein-based vaccines, with 35% of all available COVID-19 vaccines, are the most common technique in the vaccine production, and then there are vaccines of non-replicating viral vector (13.3%), mRNA1 (12.1%), DNA (10.2%), replicating viral vector (9.8%), and inactivated vaccines (8.2%). The most frequently recognized adverse effects within 7 days of each vaccine dose involved fever, fatigue, headache, chill, and myalgia. The mRNA-based vaccines were associated with a higher occurrence of local side effects (78.3 vs. 70.4%; Sig. = 0.064), whereas the viral vector-based vaccine was associated with a higher prevalence of systemic side effects (87.2 vs. 61%; Sig. < 0.001). Based on the evidence and articles in the field of vaccination, AstraZeneca-Oxford and Sinopharm vaccines reported the highest and lowest side effects, respectively. Because of being emerging, pathogenicity, and high infectivity of COVID-19, vaccination against the disease to prevent its incident rate and decrease the prevalence rate is recommended immediately. Being informed of various aspects of the existing vaccines such as efficacy, effectiveness, safety, etc.can accelerate to make effective and useful choices and consequently have a vaccinated community against the epidemic.
ABSTRACT
BACKGROUND: Coronaviruses are major pathogens of respiratory system causing different disorders, including the common cold, Middle East respiratory syndrome, and severe acute respiratory syndrome. Today's global pandemic coronavirus disease 2019 (COVID-19) has high mortality rate, with an approximate of 20% in some studies, and is 30-60 times more fatal than the common annual influenza, However, there is still no gold standard treatment for it. N-acetylcysteine (NAC) is a well-known multi-potential drug with hypothetically probable acceptable effect on COVID-related consequences, which we completely focused in this comprehensive review. MATERIALS AND METHODS: PubMed, Scopus, Science Direct, and Google Scholar have been searched. Study eligibility criteria: efficacy of NAC in various subclasses of pathogenic events which may occur during COVID-19 infection. Efficacy of NAC for managing inflammatory or any symptoms similar to symptoms of COVID-19 was reviewed and symptom improvements were assessed. RESULTS: Randomized clinical trials introduced NAC as an antioxidant glutathione analog and detoxifying agent promoted for different medical conditions and pulmonary disorders to alleviate influenza and reduce mortality by 50% in influenza-infected animals. The beneficial effects of NAC on viral disorders, including Epstein-Barr virus, HIV and hepatitis, and well-known vital organ damages were also exist and reported. CONCLUSION: We classified the probable effects of NAC as oxidative-regulatory and apoptotic-regulatory roles, antiviral activities, anti-inflammatory roles, preventive and therapeutic roles in lung disorders and better oxygenation functions, supportive roles in intensive care unit admitted patients and in sepsis, positive role in other comorbidities and nonpulmonary end-organ damages or failures and even in primary COVID-associated cutaneous manifestations. Based on different beneficial effects of NAC, it could be administered as a potential adjuvant therapy for COVID-19 considering patient status, contraindications, and possible drug-related adverse events.