Our correspondence in THE LANCET: idea of herd immunity through natural infection is deeply flawed. Uncontrolled transmission in younger people risks morbidity and mortality across the entire population, impact the workforce, overwhelm health care systems. #JohnSnowMemo 1/3
Furthermore, as of now there's no evidence for lasting protective immunity to SARS-CoV-2. Herd strategy would not end the pandemic but result in recurrent epidemics, as was the case with numerous infectious diseases before the advent of vaccination. 2/3 thelancet.com/journals/lance…
Japan, Vietnam, others, used public health to control transmission, allowing a return to near-normal. Controlling spread is the best way forward until safe, effective vaccines & therapeutics.
To support an evidence-based approach, sign the memorandum. 3/3 johnsnowmemo.com
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Science magazine: We must shift our thinking and focus on Airborne transmission of SARS-CoV-2.
Inhalation is a major route. Viruses in large droplets fall to the ground in seconds within 2 m. Viruses in aerosols remain suspended for hours, like smoke, and are inhaled 1/4
Aerosols are highly concentrated near an infected person, but they can also travel more than 2 m and accumulate in poorly ventilated indoor air, leading to superspreading events. Even without symptoms thousands of virus-laden aerosols are released by breathing and talking 2/4
Thus, it's more likely to inhale aerosols than be sprayed by droplets so we must focus on airborne transmission. In addition to masks, distancing, hygiene, we need guidance to move activities outdoors, improve indoor air w/ventilation & filtration & protect high-risk workers 3/4
NIH STUDY: 3 interventions had the most impact on COVID infections: closing schools, closing bars, wearing masks.
Here's Maryland where trajectory of case rate (green) hospitalizations (blue) and death (black) all change with a few days of lag time after closures🧵 1/n
Researchers also looked at school closure, alone. Here's Georgia where school closure occurred prior to closing bars and appears to cut the rate of infections (green) in half, beginning 8-14 days post-closure. Rates of hospitalizations (blue) & death (black) also went down (2/n)
Mask mandates also led to a drop in the rate of infections (green); drops in the rates of hospitalizations (blue); and deaths (black) "Mandating masks is to drop the slopes about 2 fold". Here's New Jersey (3/n)
VIRUS RESURGING, and it's not even winter yet: after crushing the curve, France🇫🇷/Spain🇪🇸 recording more cases than during prior peak. Consequence of ill-prepared reopening, travel, spread among youth, bar-goers...In some place ICUs almost at saturation: wapo.st/3ck8qgl🧵
In the meantime, as Israel's cases soar, it became the first country to enter into a second lockdown. With some hospitals at capacity and turning patients away, the military is stepping in to set up field hospitals: bit.ly/3kBoTj7 2/4
Iran🇮🇷is in trouble: Among earliest to be hit, now in its 3rd wave. Each wave's baseline worse than last. Iran also coming off holiday travel & inadequate masking:bit.ly/2EmFuI5
“We no longer have orange and yellow, the whole country is in red" - Dep. Health Minister 3/4
CDC finally acknowledged what scientists have been saying for months:
The virus isn't just spreading through large repiratory droplets that fall under gravity (6ft rule) but on small ones too that can travel farther. 1/3 newsweek.com/cdc-coronaviru…
This highlights the need for ventilation, in addition to masks, physical distancing, and hygiene. There are numerous examples of longer-distance aerosol transmission in indoor spaces. A few examples here: 2/3
This has been the defacto view in many countries. The Feb 3rd scientific study that characterized the virus even says "we propose that the disease could be transmitted by airborne transmission.."
1. CDC: nearly 11,000 exposed to coronavirus on flights. Agency investigated 1,600 cases of people who flew while at risk of spreading the coronavirus, identifying nearly 11,000 people who potentially were exposed to the virus on flights 🧵 washingtonpost.com/local/traffica…
2. According to story, CDC contends viruses don't spread easily on planes w/air filtration systems, but being in close proximity to people for long periods is a problem. CDC’s guidance for travel is that staying home is safest. Indeed, in-flight transmission has been observed...
3. Yesterday researchers published an example of SARS-CoV-2 spread on planes. In March, a super-spreading event on a 10-hour London to Hanoi flight led to 16 Infections due to what is thought to be airborne transmission on the aircraft...
1. Japan has a remarkably low death rate despite avoiding harsh lockdowns. That's because it a) recognized early that the virus doesn't just transmit at close distances, but also long-range & b) its public adheres to public health guidance. Western nations should emulate these 🧵
2. One feature of the virus is super-spreading where small minority can infect many others, often in crowded, poorly ventilated places. Few examples below👇. While @CDCgov, @WHO, others ignored or were too slow to acknowledge this, Japan embraced it early.
3. It did that by advocating for the 3 Cs: avoid close contact, crowded places, and closed spaces WITH POOR VENTILATION. In other words, the virus doesn't just come out of your mouth and fall to the ground within 6 ft, but can float in the air you breathe, so mix in fresh air.