Despite apparent extensive air and surface contamination of  hospital environment, no infectious samples were grown.  A cutoff of RT-PCR of ct 30 or less is likely to be associated with infectious specimens.

“Re-positive” cases are unlikely to be infectious as no intact RNA single helix was detected or live virus isolated. “Re-positive” discharged cases are caused by intermittent shedding of cells containing remnant RNA.

No viral growth was detected in respiratory, urine, stool and blood samples despite a positive RT-PCR very soon after admission.

Half of the under 16s who were positive for SARS CoV-2 shed live viruses indicating the possibility of contagiousness. However, numbers were very small (out of 628 samples 23 were positive and 12 were live shedders.

The threshold PCR Ct value for successful virus isolation was less than 32 for the N gene target. A Ct cut-off of ≥37 was not indicative of viable virus.

Higher quality studies of the accuracy of serological tests for Covid-19 are needed. Current evidence indicates that they are insufficiently accurate for use in point-of-care testing for Covid-19.

The threshold PCR Ct value for successful virus isolation was less than 32 for the N gene target. A Ct cut-off of ≥37 was not indicative of viable virus.

Molecular detection of SARS-CoV-2 RNA did not mean infectious virus was present.   The use of Ct values and clinical symptoms in combination with PCR testing for SARS-CoV-2 provides a more accurate assessment of the potential for infectious virus shedding.

In six UK hospitals in April-May 2020 the point prevalence of SARS-CoV-2 carriage was 2.0% (23/1152 participants) and the median cycle threshold value 35.7 (IQR:32.4–37.6).

When prevalence of COVID-19 is very low, routine and repeated screening is unlikely to have significant value. This is underlined by the finding that the majority of healthcare workers testing positive by PCR in this study were unlikely to be infectious.

During lockdown in South Korea, positive PCR-test cases of COVID-19 were identified among 12% of household contacts and 1.9% of non-household contacts.

In respiratory specimens of COVID-19 patients mainly with mild disease culturable SARS-CoV-2 and subgenomic RNA (good indicator of replication) was rarely detectable beyond 8 days after onset of illness although virus RNA by RT-PCR remained for up to 70 days.

RT-PCR cycle threshold (Ct) values correlate strongly with cultivable virus and likelihood of infectiousness.

Patients with respiratory manifestations of COVID-19 produce aerosols in the absence of  aerosol-generating procedures that may contain viable SARS-CoV-2.

Many SARS-CoV-2 infected people remained asymptomatic for a prolonged period, and viral load was similar to that in symptomatic patients. Isolation of infected persons should be performed regardless of symptoms.

Lower Cycle threshold values may be associated with worse course of illness and outcomes and threshold values may be useful in predicting the clinical course and prognosis of patients.

Patients with severe or critical COVID-19 may shed infectious virus for longer periods of time compared to what has been reported for in patients with mild COVID-19. Quantitative viral RNA load assays and serological assays should be used for test-based strategies to discontinue or de-escalate infection prevention and control precautions.

A 50 year old woman continued to shed live virus until day 18 and non viable virus until day 63 from symptom onset.

Viable viral isolates were extracted from sputum (n=7), stool samples (n=3) and  one nasopharyngeal sample  indicating that the SARS-CoV-2 is capable of replicating in stool samples

SARS-CoV-2 RNA was positive in stools, nasopharyngeal and oropharyngeal swabs at different time points.

There was a significant relationship between Cycle Threshold (Ct) value and culture positivity rate: samples with Ct values of 13–17 all had positive culture. Culture positivity rate decreased progressively according to Ct values to reach 12% at a Ct of 33.

Intestine SARS-CoV-2 infection affects the disease course of COVID-19 and the digestive system is the main target organ of SARS-CoV-2 in some patients.

There was viable SARS-CoV-2 in saliva, urine, and stool from COVID-19 patients up until days 11 to 15 of the clinical course suggesting that viable SARS-CoV-2 can be secreted in various clinical samples as well as respiratory specimens.

Cycle threshold may be a predictor of culturability but the small sample size of this study needs developing to propose an acceptable threshold or ways to calibrate PCR to achieve a high PPV on culturability and hence infectiousness. Viral genome integrity isolation is also an important pointer to infectivity

Three children showed a prolonged presence of SARS‐CoV‐2 in feces after throat swabs were negative.

An asymptomatic child was positive for a coronavirus by reverse transcription PCR in a stool specimen 17 days after the last virus exposure.

In a single case report, SARs-CoV-2 was detected in the throat and rectum of the  patient with COVID‐19.

Stool samples from 9/17 confirmed patients (53%) were positive on RT-PCR analysis.

SARS-CoV-2 can be shed in the stool and the assessment of both fecal and respiratory specimen is recommended

SARs-CoV-2 viral RNA was detected in the stools of two women out of the case series of five patients

Stool obtained in a single case report was positive for SARs-CO-V-2 on day 7 of the illness.

SARS-CoV-2 RNA was detected in at least one nasopharyngeal (NP) swab, 11/12 oropharyngeal (OP) swab and 7/10 in the stool. 

SARs-CoV-2 RNA was readily detected in the blood (6/57 patients) and anal swabs (11/28 patients).

Prolonged virus shedding is observed in the respiratory tract and feces of children at the convalescent stage.

SARS-CoV-2 Virus was detectable in the stool of 4 of 8 hospitalized patients.

Virus was found in urine, blood, anal swabs (n =2) and oropharyngeal swabs of nine patients diagnosed with COVID-19

Clearance of viral RNA in patients’ stools was delayed compared to oropharyngeal swabs.

SARS-CoV-2 infects enterocyte lineage cells in a human intestinal organoid model.

SARS-CoV-2 Vero cell infectivity of respiratory samples from SARS-CoV-2 positive individuals was only observed for RT-PCR Ct < 24 and symptom onset to test of < 8 days. 

Infectivity of patients with Ct >24 and duration of symptoms >8 days may be low.

All samples taken were COVID 19 cases in isolation facilities were contaminated, indicating that SARS-CoV-2 may spread through both direct (droplet and person-to-person) as well as indirect mechanisms (contaminated objects and airborne transmission). The concentration of contamination was independent of patients’ symptoms and coughing. The findings support the use of airborne isolation precautions when caring for COVID-19 patients.

Nine cases of COVID-19 that provide proof of active virus replication in tissues of the upper respiratory tract.

SARS-CoV-2 was detected in the rectum of a COVID-19 patient during the incubation period. There was direct evidence of replication of SARS-CoV-2 in the intestine.

In a hospital treating COVID-19 patients, SARS-CoV-2 RNA was found widely distributed in surface and air samples.

Widespread contamination of commonly used surfaces including personal protective equipment  imply the absolute requirements for routine cleaning and disinfection of surfaces.

Sixty seven percent (28/42) laboratory-confirmed hospitalised COVID-19 patients tested positive for SARS-CoV-2 RNA in stool specimens; this was not associated with the presence of GI symptoms or severity of illness. Among them, 18 (64%) patients remained positive for viral RNA in the feces after the pharyngeal swabs turned negative, for a duration of 6 to 10 days.

This very early study established the likelihood of person to person transmission of SARS-CoV-2, in hospital and family settings. It also highlighted the possibility of transmission from asymptomatic carriers.

This reanalysis of data from Ningbo, China, showed no difference in the transmission rates of coronavirus between symptomatic and asymptomatic cases.

Following implementation of control measures in Hunan Province, household transmission accounted for most cases, suggesting effectiveness of lockdown measures. Transmission from asymptomatic relatives was observed (two cases).

Symptom-based screening might not identify SARS-CoV-2 infections in independent and assisted living facility residents.

Severity of symptoms is no guide to intensity of viral shedding but all post cleaning samples were negative and current decontamination measures appeared sufficient.

SARS-Cov-2 RNA were positive from inlets of the sewage disinfection pool and negative from the outlet of the last sewage disinfection pool but no viable virus was detected by culture. Strict disinfection and hand hygiene could decrease the hospital-associated COVID-19 infection risk of the staffs in isolation wards.

Within a family cluster of eight  cases among nine family members, clinical manifestations varied from asymptomatic to severe pneumonia, and timing of symptom onset varied.

Evidence from early in the pandemic suggests that most SARS-CoV-2 infections are not asymptomatic throughout the course of infection, and that transmission by presymptomatic accounts for around 40-60% of transmission and asymptomatic cases accounts for around 15% of transmission.

Among 77 transmission pairs, highest viral load in throat swabs was observed at the time of symptom onset and declined thereafter; therefore infectiousness may peak prior to symptom detection.

This preliminary report shows that 21 people were established to be associated with a COVID-19 case in a ski resort in France that led to 12  subsequent infections in France, UK and Spain.

This study of exposure to an index case in a primary care hospital found a low risk of SARS-CoV-2 transmission. It suggests that routine short clinical examinations and short physical contacts did not facilitate transmission.

Cases in this study in Bavaria, Germany presented with predominately mild, non-specific symptoms. Infectiousness before or on the day of symptom onset was substantial. The incubation period was often short and false-negative tests occurred.

For 71 cases observed in Brunei, factors associated with higher onward transmission among 1,755 close contacts were attendance at local religious gatherings and household contact. Workplace and social setting transmission was low.

This prospective study of 148 household contacts found a secondary infection rate of 32% within households.

Within family clusters, the number of secondary cases was two to three times higher among spouses than children, parents or other family members.

Three possible origin theories are proposed and discussed. Not enough data are available to accept or reject any of the hypotheses.

Gastrointestinal symptoms are common in COVID-19 patients and were observed with increased prevalence as the epidemic progressed in China. SARS-CoV-2 enters GI epithelial cells, and the faeces of COVID-19 patients are potentially infectious.

No live SARS-CoV was found in any sewage samples from two hospitals receiving COVID-19 patients. SARS-CoV RNA was detected in sewage concentrates of two hospitals receiving SARS patients prior to disinfection, and occasionally after disinfection.

SARS-CoV-2 was detected in sewage 41 days before the declaration of the first COVID-19 case in Spain and in frozen samples dating back to 12 March 2019. If confirmed, the results suggest SARS CoV-2 has been around longer than first thought.

Among 9,809 healthcare employees in a UK hospital in the south-east, an increased risk of COVID-19 was found in staff in acute medicine, among Black and Asian staff, and porters and cleaners. Protective interventions including PPE appeared to reduce risk among intensive care staff.

In a laboratory study, human enterocytes expressing high ACE2 receptor levels could support infection with SARS-CoV-2. However, the virus is rapidly inactivated in the GI tract, and no infectious virus was obtained from stool samples from COVID-19 patients.

Among a group of hospitalised patients with low severity COVID-19, digestive symptoms were present in 57%. Patients with digestive symptoms were more likely to be fecal virus-positive than those with respiratory symptoms.

This study indicated that RNA of SARS-CoV-2 maybe shed via multiple bodily routes, and highlights that COVID-19 is found in anal swabs sometimes when oral swabs show no viral RNA.

This review reports that the Gastrointestinal tract supports the growth of SARS-CoV-2 to an extent similar to previous SARS infections and that gastric symptoms are frequently experienced in COVID-19.

Various observational and mechanistic evidence supports that SARS-CoV-2 can infect and be shed from the human gastrointestinal tract.

SARS-CoV-2 can infect bat intestinal cells, and demonstrated SARS-CoV-2 replication in human intestinal organoids, suggesting that the human intestinal tract might be a transmission route of SARS-CoV-2.

SARS-CoV-2 RNA was detected in serum, urine or stool samples in 20% of patients hospitalised with COVID-19. However, the virus could not be isolated from these samples and therefore the risk of transmission via these media is not established. 

This case series of 28 hospitalised patients for whom faeces samples were available indicated that infectious virus was present in faeces from two cases who also tested positive for viral RNA by RT-PCR.

The observed rate of secondary transmission among household contacts of hospitalised patients with SARS-CoV-2 infection was 30%.

Several cases were apparently transmitted from a supermarket worker.

This study of two cases and six subsequent infections amongst close family contacts suggests SARS-CoV-2 transmission through asymptomatic or paucisymptomatic infections is possible.

Of 107 surface samples (37 from toilets, 34 from other surfaces in isolation rooms and 36 from other surfaces outside isolation rooms). Four samples were positive (2 two ward door door-handles, one bathroom toilet toilet-seat cover and one bathroom door door-handle). Three were weakly positive from a bathroom toilet seat, one bathroom washbasin tap lever and one bathroom ceiling exhaust louvre. One of the 46 corridor air samples was weakly positive.

The secondary attack rate of SARS-CoV-2 within households was 16%. Increased age and being the spouse of the index case increased risk of transmission. Isolation within the home of the index patients, at the onset of symptoms, prevented household transmission.

2.6% of close contacts of cases contracted COVID-19; almost half were asymptomatic or had  mild infection. The main transmission appeared to take place via household contacts.

Based on data from 39 countries, SARS-CoV-2 can remain stable within water for up to 25 Days. Country-specific risk of infection posed by faecal contaminated water is environment-dependent, with water flow and temperature as important variables.

Infection rate was high and clinical harm was considerable onboard the cruise ship. A number of operational difficulties hampered ideal isolation and quarantine procedures onboard.

This study of choir practice attendees suggests that transmission of COVID-19 was facilitated by close proximity and physical contact and may have been augmented by the act of singing.

This study highlights the variation possible in transmission between close contacts and also that cases’ clinical experience is highly variable including asymptomatic.

Gatherings likely to involve physical greetings and prolonged close proximity probably increase transmission of SARS-CoV-2.

Extensive uncertainty on the ecology of SARS-CoV-2 makes it hard to make specific recommendations on handling and prevention of transmission. CoV are susceptible to heat, surfactants and low PH.

Some of the variations in COVID-19 transmission between cities worldwide can be explained by higher temperature and humidity being associated with lower transmission rates.

Lower weather temperatures were associated with higher COVID-19 transmission. There might be a most conducive temperature for the viral transmission, which may partly explain why it first broke out in Wuhan at that time.

Quantitative monitoring of SARS-CoV-2 genomes in wastewaters may enhance surveillance intelligence of circulation at local or regional scales.

SARS-CoV-2 was detected in the sewage of five sites a week after the first COVID-19 case in the Netherlands. Even at low COVID-19 prevalence sewage surveillance could be a sensitive tool to monitor the viral circulation.

Fecal discharge continues long after respiratory shedding of COVID-19 has ceased.

In children, the orofecal route is an alternative route of transmission, regardless of presenting COVID 19 symptomatology. Exclusion of SARS-CoV-2 infection by single time point nasopharyngeal swabs should not be used in children.

Many hospital surfaces and air samples contained viral RNA. Viable virus was not cultured from any sample.

SARS-CoV-2 may both infect the gastrointestinal system and transmit via a faecal-oral route. 

In 98 hospitalized COVID-19 cases, patients’ faecal samples remained positive for SARS-CoV-2 for a mean of 11 days (maximum 5 weeks) after respiratory tract samples became negative.

A small pilot sample of 14 cases  indicated agreement for the presence of COVID-19 between oropharyngeal sample and fecal samples.

SARS-CoV-2 RNA fragments have been identified in sewage in Italy however the WHO protocol for sewage treatment of enveloped viruses after appropriate modifications is viable. The authors report a novel RT PCR test for screening of waters.

There is a high rate of PCR positive persistence of SARS-CoV-2 in faecal samples of patients with COVID-19.

Recreational water could have concentration of SARS-CoV-2 agent via faulty wastewater management

Three children with mild symptoms who were SARS‐CoV‐2 throat swab specimen negative on discharge from hospital were stool positive 10 days post-discharge

In some children, fecal shedding may be a sign of prolonged mildly asymptomatic infection and represent the final phase of the disease.

Fecal shedding in children with COVID-19 occurs on average nine days longer than by the respiratory route

Coroviridae have been isolated in different types of liquids from waste to surface water but in general, they appear to be unstable. Chlorination and higher temperatures lead to their inactivation.

Transmission rates varied by closeness of contact and by type of contact. A single case travelling on a bus and attending a mass gathering appeared to be responsible for infecting 25 individuals

COVID-19 cases in their presymptomatic period were at least as infectious as during their symptomatic period, and household contacts and elderly people were the most susceptible to infection.

Case isolation and contact tracing reduces the time during which cases are infectious in the community.

None of 120 contacts of a patient with initially undetected COVID-19 subsequently became infectious, suggesting SARS-CoV-2 is not spread by an airborne route. 

High attack rates were identified for workers in an office space.  A map of the workspace and cases demonstrates the likelihood of close working contact increasing risk.

SARS-CoV-2 was deleted for the first time in Australia using RT-qPCR assay, confirmed by sequencing

18% of cases were estimated to be asymptomatic on board the Diamond Princess cruise ship 

Seasonal temperature is associated with COVID-19 transmission globally, with 1°C increase in local temperature associated with 13% fewer cases.

Rapid spread may have been facilitated by significant numbers travelling outside of Hubei before lockdown.

SARs-CoV-2 may be transmitted oro-fecally, but the number of studies in the present study with findings of viable virions in the faeces is small making this mode of transmission uncertain.

Temperature and relative humidity were negatively correlated with daily new cases and daily new deaths of COVID-19.

Administrative organisation issues, human bias, and bureaucracy in relevance to the epidemic are key factors in the extreme outbreak in Northern Italy.

The transmission was highest around the time of symptom onset and reduced quickly over subsequent days. Secondary infection was higher among household contacts than that in healthcare or other settings.

Unprotected, prolonged patient contact, as well as certain exposures, including some aerosol-generating procedures, were associated with SARS-CoV-2 infection. 

Transmission in Zhuhai appears to be occurring mainly within close groups such as families.

No transmission among non-household contacts was detected. Among 15 household contacts, only 2 secondary cases (each the spouse of the respective case) were detected.

Among 12 Health care workers diagnosed with COVID-19 asked to recall their working patterns pre-outbreak, poor sleep quality and high working pressure were positively associated with higher risks of COVID-19 diagnosis.

Children were more likely to have asymptomatic infections, milder conditions, faster recovery, and better prognosis than adults

Investigation of 243 cases of COVID-19 in Singapore identified seven clusters in which presymptomatic transmission was the most likely explanation for secondary infections.

Passengers and crew in the cruise ship experienced high transmission rates, hypothesised to be due to the close quarters and confined living spaces.

In transmission events, after sharing a meal or staying at a chalet the secondary attack rate is estimated as very high.

Most transmission of COVID-19 occurred at the early stage or even before symptom onset, as symptoms developed and progressed the secondary attack rate decreased

The mean household SAR was 15% (95% CI: 12% to 19%) – ranging from 6.6% in Taiwan to more than 30% in four Chinese cities. Secondary attack rate from symptomatic index cases contact was greater than asymptomatics. 

Strong atmospheric stability with dry conditions favoured viral spread by short-range droplet transmission.

Changes in weather alone will not necessarily lead to declines in COVID-19 case counts without the implementation of extensive public health interventions.

The transmission of COVID-19 is associated with the 30 to 50 degree N’ longitude corridor and weather patterns and low specific and absolute humidity.

Calm, cold, dry and overcast conditions are favourable to the transmission of COVID-19.

Swift action by diagnosis, testing, contact-tracing and isolation would have probably avoided the majority of 619 cases aboard. 

Eighty-one percent of COVID 19 patients on a cruise ship were asymptomatic. Prevalence on affected cruise ships is likely to be underestimated and monitoring after disembarkation is necessary.

The accelerated and vast diffusion of COVID-19 in Northern Italy was associated with the duration of cities’ exposure to polluted air.

In one of the two original epicentres of the outbreak in Northern Italy, Vò Euganeo, cases were  infected in the community before lockdown, or subsequently from asymptomatic infected people living in the same household.

Separate access and segregation of potentially infected patients are required to prevent or control nosocomial outbreaks of COVID-19.

COVID-19 transmission was occurring since mid-December 2019 in Wuhan: the majority in the Huanan Seafood Wholesale Market. A lack of early testing may have missed cases, particularly those with atypical symptoms.

Seasonal coronaviruses were detected in 4% of patients with respiratory illness who were tested at primary/secondary healthcare settings.

Evidence suggests reduced transmission in high ambient temperatures and humidity, but it is limited and inconsistent.

The transmission was slow in the early weeks of the pandemic in Nigeria compared with other countries, which may be related to differences in case ascertainment.

Temperature and humidity are strongly associated with the variation of the growth rate of Covid-19 cases across the globe in the early phase of the outbreak.

In a multivariable model only population density and the timeline remained statistically significant.

Increases in temperature and humidity were associated with lower levels of  COVID-19.

Transmission of COVID-19 was associated with weakly associated with relative or absolute humidity and not associated with latitude and temperature.

On the basis of the reconstruction of an outbreak of COVID-19 in a skilled nursing facility, the presence of symptoms is not a sufficient indicator of infection. Viral shedding can continue for at least a week after testing positive.

None of the 455 contacts of a single case of asymptomatic SARs-CoV 2 turned positive after a month.

The transmission of SARS-CoV-2 in South  Korea was exacerbated by super spreading events in confined settings, including a hospital, a church and a gym.

The results found evidence of SARS-CoV-2 transmission clusters for 152 events, which was classified into 18 types of settings.

For the references see the online database.

This pilot study in India found SARS-CoV-2 RNA in fecal samples from 12 symptomatic and asymptomatic COVID-19 patients.

Live virus has been isolated from the stools of one severe pneumonia case, pointing to a possible oro-fecal spread.

In this case series from China, two stool specimens out of 44 positives contained live virus, suggesting that orofecal transmission is possible. Transmission of the virus by respiratory and extra respiratory routes may help explain the rapid spread of disease.

This retrospective study of 133 hospitalised COVID-19 patients identified 22 whose sputum or fecal samples tested positive after their pharyngeal swabs became negative.

This study of ten children with COVID-19 found that symptoms among children were nonspecific and relatively mild; rectal swabs tested positive among 8/10 cases even once nasopharyngeal tests became negative.

Transmission of COVID-19 may take place by fine droplets emitted by infected people with no symptoms when they speak or breathe without necessarily coughing or sneezing.