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Denser places, assumed by many to be more conducive to the spread of the coronavirus that causes COVID-19, are not linked to higher infection rates, say researchers.

The study, led by Johns Hopkins University, published in the Journal of the American Planning Association, also found that dense areas were associated with lower COVID-19 death rates.

"These findings suggest that urban planners should continue to practice and advocate for compact places rather than sprawling ones, due to the myriad well-established benefits of the former, including health benefits," says study lead author Shima Hamidi from Johns Hopkins Bloomberg School of Public Health in the US.

For their analysis, the researchers examined SARS-CoV-2 infection rates and COVID-19 death rates in 913 metropolitan counties in the US.

When other factors such as race and education were taken into account, the authors found that county density was not significantly associated with county infection rate.

The findings also showed that denser counties, as compared to more sprawling ones, tended to have lower death rates--possibly because they enjoyed a higher level of development including better health care systems.

On the other hand, the research found that higher coronavirus infection and COVID-19 mortality rates in counties are more related to the larger context of metropolitan size in which counties are located.

Large metropolitan areas with a higher number of counties tightly linked together through economic, social, and commuting relationships are the most vulnerable to the pandemic outbreaks.

According to the researchers, recent polls suggest that many US citizens now consider an exodus from big cities likely, possibly due to the belief that more density equals more infection risk.

Some government officials have posited that urban density is linked to the transmissibility of the virus.

"The fact that density is unrelated to confirmed virus infection rates and inversely related to confirmed COVID-19 death rates is important, unexpected, and profound," said Hamidi.

"It counters a narrative that, absent data and analysis, would challenge the foundation of modern cities and could lead to a population shift from urban centres to suburban and exurban areas," Hamidi added.

The analysis found that after controlling for factors such as metropolitan size, education, race, and age, doubling the activity density was associated with an 11.3 per cent lower death rate.

The authors said that this is possibly due to faster and more widespread adoption of social distancing practices and better quality of health care in areas of denser population.

The researchers concluded that a higher county population, a higher proportion of people age 60 and up, a lower proportion of college-educated people, and a higher proportion of African Americans were all associated with a greater infection rate and mortality rate.

Los Angeles, Apr 28: People who experience loss of smell as one of the COVID-19 symptoms are likely to have a mild to moderate clinical course of the disease, according to a study which may help health care providers determine which patients require hospitalisation.

The findings, published in the journal International Forum of Allergy & Rhinology, follows an earlier study that validated the loss of smell and taste as indicators of infection with the novel coronavirus, SARS-CoV-2.

According to the scientists from the University of California (UC) San Diego Health in the US, patients who reported loss of smell were 10 times less likely to be hospitalised for COVID-19 compared to those without the symptom.

"One of the immediate challenges for health care providers is to determine how to best treat persons infected by the novel coronavirus," said Carol Yan, first author of the current study and rhinologist from the UC San Diego Health.

"If they display no or mild symptoms, can they return home to self-quarantine or will they likely require hospitalisation? These are crucial questions for hospitals trying to efficiently and effectively allocate finite medical resources," Yan said.

The findings, according to the researchers, suggest that loss of smell may be predictive of a milder clinical course of COVID-19.

"What's notable in the new findings is that it appears that loss of smell may be a predictor that a SARS-CoV-2 infection will not be as severe, and less likely to require hospitalisation," Yan said.

"If an infected person loses that sense, it seems more likely they will experience milder symptoms, barring other underlying risk factors," she added.

Risk factors for COVID-19 previously reported by other studies include age, and underlying medical conditions, such as chronic lung disease, serious heart conditions, diabetes, and obesity.

In the current study, the scientists made a retrospective analysis between March 3 and April 8 including 169 patients who tested positive for COVID-19 at UC San Diego Health.

They assessed olfactory and gustatory data for 128 of the 169 patients, 26 of whom required hospitalisation.

According to the researchers, patients who were hospitalised for COVID-19 treatment were significantly less likely to report anosmia or loss of smell -- 26.9 per cent compared to 66.7 per cent for COVID-19-infected persons treated as outpatients.

Similar percentages were found for loss of taste, known as dysgeusia, they said.

"Patients who reported loss of smell were 10 times less likely to be admitted for COVID-19 compared to those without loss of smell," said study co-author Adam S. DeConde.

"Moreover, anosmia was not associated with any other measures typically related to the decision to admit, suggesting that it's truly an independent factor and may serve as a marker for milder manifestations of Covid-19," DeConde said.

The researchers suspect that the findings hint at some of the physiological characteristics of the infection.

"The site and dosage of the initial viral burden, along with the effectiveness of the host immune response, are all potentially important variables in determining the spread of the virus within a person and, ultimately, the clinical course of the infection," DeConde said.

If the SARS-CoV-2 virus initially concentrates in the nose and upper airway, where it impacts olfactory function, that may result in an infection that is less severe and sudden in onset, decreasing the risk of overwhelming the host immune response, respiratory failure, and hospitalisation, the scientists added.

"This is a hypothesis, but it's also similar to the concept underlying live vaccinations," DeConde explained.

"At low dosage and at a distant site of inoculation, the host can generate an immune response without severe infection," he added.

Loss of smell, according to the study, might also indicate a robust immune response which has been localised to the nasal passages, limiting effects elsewhere in the body.

Citing the limitations of the study, the scientists said they relied upon self-reporting of anosmia from participants, which posed a greater chance of recall bias among patients once they had been diagnosed with COVID-19.

They added that patients with more severe respiratory disease requiring hospitalisation may not be as likely to recognise or recall the loss of smell.

So the researchers said more expansive studies are needed for validating the results.

Consumer watchdog Which? has claimed that more than one billion Android phones and tablets are vulnerable to hackers as they no longer supported by security updates.

According to the research report, the most at-risk phones are any that run Android 4 or older and those smartphones running Android 7.0 which can not be updated are also at risk.

Based on data from Google analysed by Which?, two in five android device users around the world are no longer receiving the important updates. Currently, those devices are unlikely to have issues, but the lack of security leaves them open to attack.

"It is very concerning that expensive Android devices have such a short shelf life before they lose security support, leaving millions of users at risk of serious consequences if they fall victim to hackers," Kate Bevan editor Which? said in a statement.

"Google and phone manufacturers need to be upfront about security updates with clear information about how long they will last and what customers should do when they run out. The government must also push ahead with planned legislation to ensure manufacturers are far more transparent about security updates for smart devices and their impact on consumers," Kate added.

Android phone released around 2012 or earlier, including popular models like the Samsung Galaxy S3 and Sony Xperia S, are particularly at risk to hackers.

Which? has made suggestions to Android users on what to consider if they have an older phone that may be at risk.

Any Android device which is more than two years old, check whether it can be updated to a newer version of the operating system. If it is on an earlier version than Android 7.0 Nougat, try to update via Settings> System>Advanced System update.

In case a user is not able tto update the phone, the device could be at risk of being hacked if it is running a version of Android 4 or lower.

A user also need to be careful about downloading apps outside the Google Play store and should also install a mobile anti-virus via an app.