Two months ago, Ladders predicted that the summer months might play a major role in reducing COVID-19 transmissions.
Although based on preliminary research published at the time, previously studied coronaviruses all yielded to sunlight.
The SARS virus that caused the epidemic of 2002 and the MERS virus that caused the outbreak of 2012 both ended up being acutely seasonal, with transmission rates peaking between January and May.
Even if we couldn’t say the same outcome would apply to SARS-CoV-2 with moral certainty, we did know that the mutated virus is the most stable at 4°C. At this temperature, its presence is even detectable after two weeks.
Seasonal intervention just gained more credibility with a new study published in the journal Photochemistry and Photobiology.
In it, the authors, Jose-Luis Sagripanti and David Lytle posit that the summer sun can eliminate SARS-CoV-2 in a little over 30 minutes.
“Using a model developed for estimating solar inactivation of viruses of biodefense concerns, we calculated the expected inactivation of SARS-CoV-2 virus, cause of COVID-19 pandemic, by artificial UVC and by solar ultraviolet radiation in several cities of the world during different times of the year,” the authors wrote in the new paper. ”The presented data indicate that SARS-CoV-2 should be inactivated relatively fast (faster than influenza A) during summer in many populous cities of the world, indicating that sunlight should have a role in the occurrence, spread rate, and duration of coronavirus pandemics.”
The model employed by the researchers showed that UVB in sun rays has been deactivating SARS-CoV-2 in regions across the globe at different times of the year.
Sagripanti and Lytle are so confident in the findings presented in their new study they paired its release with a censure of mandatory stay-at-home orders, saying that after winter ended these measures began to inflict more harm than good:
”The UV sensitivity estimated here for SARS-CoV-2 is compared with those reported for other ssRNA viruses, including influenza A virus. The results indicate that SARS-CoV-2 aerosolized from infected patients and deposited on surfaces could remain infectious outdoors for a considerable time during the winter in many temperate-zone cities, with continued risk for re-aerosolization and human infection,” the report went on.
Officials in Singapore, China were able to continue commercial operations and avoid spikes in coronavirus transmissions by simply wearing masks and adhering to guidelines set forth by health systems.
Things are more complicated in the US for several reasons. Without going into them all here, I’ll say virologists have been forced to adjust their language to appease our liberty boners. To a lot of the population, being told to shelter in place feels like an attack on their freedoms.
Thankfully this new report arrived at the beginning of gradual shutdown easing, and its projections have been substantiated by previously published literature.
In a recent report, Qasim Bukhari and Yusuf Jameel, of the Massachusetts Institute of Technology, analyzed global cases of COVID-19 and found that 90% of infections are transmitted in areas that are between 37.4 and 62.6 degrees Fahrenheit (3 to 17 degrees Celsius) and with an absolute humidity of 4 to 9 grams per cubic meter g/m3 (which is a calculation of moisture in the air irrespective of temperature.)
Even if a second COVID-19 is imminent, daylight might buy overwhelmed medical facilities time to regroup.