Background Despite the streaks of severity, severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection is, in general, less frequent and severe in children than in adults. We searched for causal evidence of this mystery. Data sources An extensive search strategy was designed to identify papers on coronavirus disease 2019 (COVID-19). We searched Ovid MEDLINE, PubMed, EMBASE databases, and Cochrane library and carried out a review on the causes of this dilemma. Results Our searches produced 81 relevant articles. The review showed that children accounted for a lower percentage of reported cases, and they also experienced less severe illness courses. Some potential explanations, including the tendency to engage the upper airway, the different expression in both receptors of angiotensin-converting enzyme and renin-angiotensin system, a less vigorous immune response, the lower levels of interleukin (IL)-6, IL-10, myeloperoxidase, and P-selectin and a higher intracellular adhesion molecule-1, a potential protective role of lymphocytes, and also lung infiltrations might have protective roles in the immune system-respiratory tract interactions. Finally, what have shed light on this under representation comes from two studies that revealed high-titer immunoglobulin-G antibodies against respiratory syncytial virus and mycoplasma pneumonia, may carry out cross-protection against SARS-CoV-2 infection, just like what suggested about the vaccines. Conclusions These results require an in-depth look. Properties of the immune system including a less vigorous adaptive system beside a preliminary potent innate response and a trained immunity alongside a healthier respiratory system, and their interactions, might protect children against SARS-CoV-2 infection. However, further studies are needed to explore other possible causes of this enigma.

Background Although, preliminary reports of Severe Acute Respiratory Syndrome (SARS)-CoV-2 infection suggest that the infection causes a less severe illness in children, there is now growing evidence of other rare or even serious complications of disease. Case presentation During the recent COVID-19 pandemic in Kerman, Iran, two children (an 8 year-old boy and a 6 year-old girl) were referred to outpatient Clinic of Pediatric Rheumatology with complaints of limping. Both children had experienced fever and mild respiratory tract infection. At the beginning of the second week of infection, they developed joint effusion. They both tested positive for coronavirus infection and were therefore diagnosed with post Coronavirus reactive arthritis. Both children were treated successfully with rest and Non-Steroidal Anti-Inflammatory Drugs (NSAID). They did not have any medical problems in the two months fallow up. Conclusions These two cases suggest that COVID-19 may be rheumatogenic. Highlighting the need for awareness of physicians, especially pediatricians, regarding the pathogenesis margins of this virus, as late presentations are of great importance.

Background: Identification of the etiology of acute limping in children is challenging. Both benign and life- threatening disorders can present with limp. However, among atraumatic conditions, benign conditions including toxic synovitis and post infectious arthritis are the most common causes of this dilemma. Case Presentation: During the recent COVID-19 pandemic in Kerman, South East of Iran; two pediatric patients referred to the Rheumatology clinic with new onset gait disturbance. One 8 years old boy and the other 6 years old girl who presented with hip joint pain and limping. Both of them had joint effusion jackknife of mild respiratory symptoms and fever. Altogether, precise history taking and accurate physical examination, alongside radiological investigations and positive laboratory results for coronavirus infection emphasized the diagnosis of post Coronavirus arthritis. They treated with rest and Non-Steroidal Anti-Inflammatory Drugs (NSAID) successfully, and fallowed at least for one month later.Conclusions: Here, we described the first report of post n-CoV-2 arthritis in the world in two Iranian pediatric patients, who presented with limp. Contrary to preliminary phantasms, this may indicate that the Corona virus has some rheumatogenic specifications.

Background: The COVID-19 pandemic, caused by SARS-Cov-2, has affected the care of patients with hemophilia, indicating the necessity of their vaccination. Nevertheless, there are concerns about using anti-SARS-Cov-2 virus vaccines for hemophilic patients, particularly concerning bleeding adverse events. Methods: Following a cross-sectional design, all adult hemophilic patients who received two doses of Sinopharm anti-SARS-Cov-2 virus vaccine in Afzalipour Hospital, Kerman, Iran, during May and June 2021 were recruited. The participants were followed for two weeks after receiving each dose of vaccine. Results: Fifty-one patients with a mean age of 37.07 ± 11.45 years were included, of whom 27 (61.4 %) patients experienced at least one adverse reaction. Pain was the most frequent local adverse event (occurred in 20 (39.2%) and 15 (29.4%) cases after 1st and 2nd doses, respectively). Menometrorrhagia and epistaxis were reported by two and one patients, respectively. Conclusions: Overall Sinopharm anti-SARS-Cov-2 virus vaccine seems to be safe for patients with hemophilia in the short term.

To the Editor: Although COVID-19 seems to be milder in children than adults, the SARS-CoV-2 now is showing the ugliest faces off from itself [1,2]. Recently, a severe and novel entity has emerged in children as a multi-system inflammatory syndrome. Here we report a series of affected children in southeast of Iran [3][4][5].From June 1 to August 12 of 2020, 15 pediatric patients with Kawasaki like features and a wide spectrum of clinical findings were admitted at Kerman city Afzalipour Hospital in the southeast of Iran. Four of them were more violent cases of SARS-CoV-2 infection at the end of the spectrum as MIS-C demonstrations, with positive PCR and/or anti-SARS-CoV-2 antibody results. These patients were admitted at PICU and their main symptoms were tachycardia and hypotension. One of them had an increasing pro-BNP ≥ 35,000 pg/mL but troponin and CPK-MB were in normal ranges. All patients with MIS-C had severe cardiac dysfunction and reduced ejection fraction (mean 20%). They received intravenous PDE3 inhibitor (milrinone) and intravenous epinephrine, for an average of 5 d. The electrocardiogram had nonspecific changes such as sinus tachycardia and abnormal ST-T changes. All patients received IVIG 2 g/kg, and all in adjacent to MIS-C and four in Kawasaki like spectrum received glucocorticoids. The mean age of our patients was 49.6 mo and they had a wide array of manifestations of persistent fever, rash, diarrhea, vomiting, moderate to severe heart failure, shock similar to toxic shock syndrome, and relative delay arthritis. Four patients with MIS-C had either moderate to severe heart failure or presented with shock, requiring the vasopressor and resuscitating therapies. The electrocardiogram had nonspecific changes such as sinus tachycardia and abnormal ST-T changes. All patients received IVIG 2 g/kg, and all in adjacent to MIS-C and four in Kawasaki-like spectrum received glucocorticoids. The average length of PICU stay was 6 d, and all patients were discharged in good condition after improving their clinical symptoms. Although most patients with this syndrome are ill and have heart problems and need PICU stay, they can recover using appropriate treatment.