We conducted a systematic review and meta-analysis to investigate the possible difference in the SARS-CoV-2 viral load between asymptomatic and symptomatic COVID-19 patients. Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines were followed in abstracting data and assessing validity. We searched MEDLINE, Scopus, Web of Science and Google Scholar for all investigations in the English language, reporting data on the threshold cycle (Ct) from real-time RT-PCR assays for the RNA-dependent RNA polymerase (RdRp), envelope (E) and nucleocapsid (N) SARS-CoV-2 genes in asymptomatic and symptomatic COVID-19 patients. Results: Overall, 703 COVID-19 patients (553 symptomatic and 150 asymptomatic) were analyzed. Five investigations reported the mean age of patients, evidencing that asymptomatic patients were younger than symptomatic patients (34.0 vs. 40.3 years, respectively). Pooled data regarding the levels of expression of the RdRp gene revealed no significant difference between symptomatic and asymptomatic subjects. Similarly, no differences were observed comparing the mean Ct values for the E and N genes. Based on real-time RT-PCR data, no differences exist in the viral load between symptomatic and asymptomatic COVID-19 subjects considering Ct values for RdRp, E and N genes\' expression. Asymptomatic subjects may represent a reservoir of the infection and significantly contribute to the maintenance of the pandemic.

The recent outbreak by a novel coronavirus originated from Wuhan, China in 2019, and is progressively spreading to other countries. Timely diagnosis of the coronavirus disease 2019 (COVID-19) improves the survival of the patients and also prevents the transmission of the infection. In this study, we reviewed the applicable and available methods for the diagnosis of COVID-19.
For the review, we systematically searched Web of Science, PubMed, and Iranian articles that were published about COVID-19 diagnostic methods with a combination of the key terms: laboratory, radiological, tests, coronavirus.
Although the current gold standard diagnostic test for this virus is real-time reverse-transcriptase polymerase chain reaction (RT-PCR), the occasional false-negative and the low sensitivity of the test should not be underestimated. A chest computed tomography (CT) scan is another diagnostic test for COVID-19, with higher sensitivity but low specificity. A combination of sensitive RT-PCR with a chest CT scan together with the clinical features are highly recommended for the proper diagnosis. Notably, there are some other sensitive and low-cost tests for evaluation of COVID-19 infection, but their validation should be approved.
Since early and accurate diagnosis of the viral disease could improve the survival rate of the patients, and halt the transmission chain, it is not surprising that tremendous attempts should be made to reduce the limitations of the tests leading to the false-negative results and to find a rapid test for the diagnosis of COVID-19.

Investigating the infectivity of body fluid can be useful for preventative measures in the community and ensuring safety in the operating rooms and on the laboratory practices. We performed a literature search of clinical trials, cohorts, and case series using PubMed/MEDLINE, Google Scholar, and Cochrane library, and downloadable database of CDC. We excluded case reports and searched all-language articles for review and repeated until the final drafting. The search protocol was registered in the PROSPERO database. Thirty studies with urinary sampling for viral shedding were included. A total number of 1,271 patients were enrolled initially, among which 569 patients had undergone urinary testing. Nine studies observed urinary viral shedding in urine from 41 patients. The total incidence of urinary SARS-CoV-2 shedding was 8%, compared to 21.3% and 39.5 % for blood and stool, respectively. The summarized risk ratio (RR) estimates for urine positive rates compared to the pharyngeal rate was 0.08. The pertaining RR urine compared to blood and stool positive rates were 0.20 and 0.33, respectively. Our review concludes that not only the SARS-CoV-2 can be excreted in the urine in eight percent of patients but also its incidence may have associations with the severity of the systemic disease, ICU admission, and fatality rates. Moreover, the findings in our review suggest that a larger population size may reveal more positive urinary cases possibly by minimizing biases.