News Scan for May 21, 2020

Wedding-related COVID-19 spread
Sunlight effect on SARS-CoV-2

Wedding triggered surge of coronavirus cases in Jordan

An investigation into a wedding-related COVID-19 outbreak in Jordan found a high transmission rate and a high rate of asymptomatic carriers, researchers from Jordan reported yesterday in Emerging Infectious Diseases.

The outbreak occurred in the middle of March when Jordan had only one confirmed case, but it led to a surge of cases that a month later made up 24% of all COVID-19 cases in Jordan and helped spur a lockdown in the city of Irbid, where the wedding took place.

The index patient was the 58-year-old father of the bride, who arrived 4 days before the wedding from Spain, where local transmission was under way. His symptoms began 2 days before the Mar 13 indoor wedding. Two days after the wedding he went to the emergency department, where he tested positive for COVID-19.

Researchers identified 350 people who had attended the wedding, and all were tested within 4 weeks of their exposure, whether or not they had symptoms. Eighty-five people tested positive for the virus; of those, 76 had attended the wedding and 9 were close contacts of confirmed case-patients who had attended the wedding. Of the wedding attendees who tested positive, 40 (52.6%) had symptoms and 36 (47.4%) were asymptomatic.

Two of the symptomatic people had serious infections, one of them an 80-year-old woman with underlying health conditions who died.

The findings underscore how COVID-19 transmission rates can be much higher in closed, crowded social gatherings, such as a wedding where close physical contact such as hugging, cheek-kissing, and hand shaking are common. Also, immediate family members usually stand at the wedding hall entrance. "These factors, in addition to crowded dancing and close face-to-face communication, likely contributed to the large number of infections from this wedding," the authors wrote.
May 20 Emerg Infect Dis report


Study indicates sunlight can kill SARS-CoV-2 on surfaces

New research shows that natural sunlight can rapidly inactivate SARS-CoV-2, the virus that causes COVID-19, on surfaces, researchers with the US Department of Homeland Security reported yesterday in The Journal of Infectious Diseases. The findings, which come with caveats, suggest that the potential for fomite transmission may be significantly reduced in outdoor environments exposed to direct sunlight.

To evaluate the influence of simulated sunlight on the persistence of SARS-CoV-2 on surfaces, the researchers exposed concentrated virus suspended in either simulated human saliva or culture media and then dried on stainless steel coupons mounted in a chamber to a light spectrum designed to represent natural sunlight.

The coupons were exposed to the simulated sunlight for differing exposures, ranging from 2 to 18 minutes, to allow estimation of the viral inactivation rate. For comparison, the researchers also exposed a series of contaminated coupons in the chamber with no simulated sunlight for 60 minutes.

The results showed that under levels of simulated sunlight representative of midday on the summer solstice at 40°N latitude (the 40th Parallel), 90% of infectious virus is inactivated every 6.8 minutes in simulated saliva dried on a surface and every 14.3 minutes in cultured media dried on a surface. Significant inactivation also occurred under lower simulated light levels but at a slower rate. Inactivation rates were near zero on the coupons not exposed to sunlight.

The inactivation rate of SARS-CoV-2 was approximately two-fold greater in simulated saliva than in culture media, but the researchers say it's unclear if the viral concentrate in simulated salvia is representative of contaminated saliva from an infected individual. They also note that while the simulated sunlight was meant to represent natural sunlight, a low level of irradiance was present below the UVB portion of the spectrum that is not present outdoors.

"The present study provides the first evidence that sunlight may rapidly inactivate SARS-CoV-2 on surfaces, suggesting that surface persistence, and subsequently exposure risk, may vary significantly between indoor and outdoor environments," the authors wrote. "However, in order to fully assess the risk of exposure in outdoor environments, information on the viral load present on surfaces, the transfer efficiency of virus from those surfaces upon contact, and the amount of virus needed to cause infection are also needed."
May 20 J Infect Dis study

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