Social distancing in action.
PARTS OF the U.S. are beginning to move from “strict social distancing” to a more relaxed “distancing in daily life”—vocabulary from South Korea’s experience; in other words, from the “hammer” of strict measures to the “dance” of testing, contact tracing and ongoing degrees of quarantine.
Loosening relies on increased responsibility of individuals: to keep a good distance from others; to wear a mask; to avoid large groups of people, especially indoors; and, when at risk—because of recent personal experience or if pinged from an “exposure notification” app—to return to stricter measures that include isolation.
In the absence of better disease surveillance tools— widespread testing and contact tracing—authorities rely increasingly on smart phone location data, although these are “remarkably blunt tools against a lethal, contagious disease,” writes Craig Timberg in the Washington Post. While decreasing mobility over time slows new infections, apps cannot tell how well people maintain social distancing once they reach their destination—did they sneeze, were there physical barriers?
According to companies that aggregate cellphone location data, many Americans appear reluctant to reopen. From Safegraph: after spending 93% of the time at home during the peak of the collective lockdown— compared with 70% in early March —by the end of April, U.S. residents were still at home 89% of the time; from Cuebiq, by state, with a peak of up to 54% of people staying home (New York), percentages from most states went down less than 10%.
For apps that track contacts and alert those at risk, privacy issues have driven Apple and Google to relabel their tracking apps “exposure notification.” As a Washington Post editorial points out, however, “any digital solution to our problem that’s sufficiently privacy-protective also won’t be sufficiently useful without a lot of humans in the loop.” The best option would be for anyone pinged to call a manual contact tracer to register status and get advice.
Among the most useful apps, the Covid Symptom Study app can predict with nearly 80% accuracy whether a person is likely to have Covid-19, based on age, sex, and a combination of four symptoms – which are the latest to rise to the top of most likely indicators of infection with the virus: loss of taste or smell, persistent cough, fatigue and loss of appetite. (Both the exposure notification apps and the Covid Symptom Study app are still under development; both will require opt-ins and express consent before they are used.)
Because the key to transmission is viral exposure over time, large groups of people congregating in enclosed indoor spaces create the highest risk. An infectious dose needs about 1,000 SARS-CoV2 viral particles—with droplets from a single cough or sneeze containing “as many as 200,000,000 (two hundred million) virus particles,” explains U. Mass Dartmouth biology professor Erin Bromage.
Staying outdoors should be the safest. In a Chinese study of 318 outbreaks involving 1,245 cases in 120 cities, fewer than .3% of infections occurred in an outdoor environment, Bromage writes. While wind can help disperse viral particles, it can also carry them from an infected individual, especially to those in the direct draft or slipstream. But, Bromage notes, because the formula is dose plus time, “you would have to be in their airstream for five-plus minutes for a chance of infection.”
Indoors, every individual presents a potential risk: at least 44% of all infections occur from people who are asymptomatic —during or for days before and after active infection. Viral particles from speaking and breathing can remain in the air for 5-10 minutes—thousands of particles per second from loud speech and more particles on an out-breath through the mouth than through the nose.
Sneezing can release 30,000 droplets, and coughing, 3,000—that can travel across a room as well as linger in the air. Specific warnings concern public toilets, which can release 8,000 droplets that can carry infection—so best to wait a few minutes after the last user flushes for droplets to fall to the floor.
With the eyes a vulnerable access point for transmission of the virus, the main advice is never to touch them. Some also recommend wearing eyeglasses (not contact lenses); and for occupational exposure protection, safety goggles on top of prescription lenses or indirectly vented goggles that fit snugly and require prescription lenses.
Abstinence-only doesn’t work for sex—and is unlikely to work when imposed on all human contact, caution public health experts experienced with the HIV epidemic. Noting the economic and psychological hardships of extreme distancing, they urge understanding that quarantine fatigue is real and warn against pandemic shaming —of anyone perceived as violating mask and distancing rules.
For contact tracing, currently the best strategy for controlling new outbreaks, the U.S. is way behind on hiring and training the hundreds of thousands of people needed for this labor-intensive work. In South Korea, for example, for one man who visited several nightclubs and four days later tested positive, contact tracers turned up 7,200 possible victims, of whom more than 100 have to date reported positive test results.
On “herd immunity,” experts are saying anywhere from 50% to 80% of the population must have been infected to slow progression of the virus. But in France and Spain, with just under 30,000 deaths each, antibody tests have been positive for 5% or less of the population—similar to results throughout the U.S.—putting all these countries at risk for second outbreaks. More worrisome, antibodies to this coronavirus might not be protective against future infection.
A better supported goal is the R0 (r-aught), or reproductive number of 1.0, meaning each infected person passes the virus to only one more person—indicating “stagnation” rather than increasing spread. Caveats include delayed accounting of a week to 10 days for the R0 and the need to combine it with total numbers of new cases. (Lower numbers of new cases give individual outbreaks a stronger influence on the R0 number.)
Among rare silver linings of this pandemic, breathing through the nose—the advice for an exhale less likely to spread the virus—can be calming. Because nose breathing encounters more resistance, the breath becomes slower and deeper, which stimulates the vagus nerve —which in turn slows and relaxes the heart and muscles, and spreads calm throughout the body.
And even with increased opening, there may be no return to the “old dispensation,” as Roger Cohen writes in a NYT Op-Ed. Cohen quotes from T.S. Eliot’s “Journey of the Magi,” from the story of the kings returning home after their visit to the newborn Christ to find themselves “no longer at ease here, in the old dispensation.”
If the “virus is a searchlight that lays everything bare,” Cohen writes, notably the “fragile environmental health of the planet,” the aftermath may include “rebalancing…from consumption to contemplation, from global to local…from frenzy to stillness, from carbon to green.”
For now, though, a kiss is no longer a kiss—not for filmmakers, not for saying hello or goodbye. And for people who can do it: stay home.
—Mary Carpenter
Well-Being Editor Mary Carpenter continues to provide corona virus updates. To read more of her posts, click here.
