On March 18 2020, the top post on Reddit’s r/all (from r/pics) was titled, “This is what happens when you tell workers to self isolate but don’t protect their incomes,” and it showed crowds of people standing close to one another on public transportation:
In the photograph, the train car shown did not appear to show a reduction in riders at the time that “social distancing” took hold in the public discourse. In a comment on the thread, its submitter asserted that the photograph had been captured on March 18 2020, but by someone else.
That person linked to a March 18 2020 tweet featuring the same photograph:
That Twitter user tagged British news agencies and reporters, writing:
Social distancing? This morning’s commute on the Victoria line. Perhaps some clearer guidance from the government would help @BBCWorld @mrjamesob @guardian
In the next tweet down, the same user attributed the photograph to their wife, a nurse:
Wow, never had any interactions on a tweet before – guess that’s what happens when everyone is home! Just for those who were asking – my wife is a nurse and sent me this at about 8am this morning (18/03)
Discussion in replies to the tweets was typically mixed — some of those responding admonished riders for not staying home, while others reiterated the point in the title — that people without replacement wages could not afford to “just stay home” in a gig economy. In additional replies, commenters lamented a lack of government coordination that might have otherwise ensured that social distancing was possible.
A day before the photograph shot to the top of Reddit’s r/all, news sites and social media placed global attention on a March 16 2020 report from researchers at Imperial College London. That report (“”Impact of non-pharmaceutical interventions (NPIs) to reduce COVID19 mortality and healthcare demand,” PDF here) had a massive effect on discussion of COVID-19 and modeled approaches to mitigating its spread.
The headline, which was misleadingly innocuous, referred to an element of the coronavirus pandemic — namely, that a vaccine for the strain was likely more than a year into the future as of March 2020. Consequently, researchers emphasized five “non-pharmaceutical” approaches, the only available strategies to reduce mortality rates for COVID-19:
- Case isolation in the home, or CI: “Symptomatic cases stay at home for 7 days, reducing nonhousehold contacts by 75% for this period. Household contacts remain unchanged. Assume 70% of household comply with the policy.”
- Voluntary home quarantine, or HQ: “Following identification of a symptomatic case in the household, all household members remain at home for 14 days. Household contact rates double during this quarantine period, contacts in the community reduce by 75%. Assume 50% of household comply with the policy.”
- Social distancing of those over 70 years of age, or SDO: “Reduce contacts by 50% in workplaces, increase household contacts by 25% and reduce other contacts by 75%. Assume 75% compliance with policy.”
- Social distancing of entire population, or SD: “All households reduce contact outside household, school or workplace by 75%. School contact rates unchanged, workplace contact rates reduced by 25%. Household contact rates assumed to increase by 25%.”
- Closure of schools and universities, or PC: “Closure of all schools, 25% of universities remain open. Household contact rates for student families increase by 50% during closure. Contacts in the community increase by 25% during closure.”
Strategies to reduce transmission of the novel coronavirus strain were not the only elements of the Imperial College London report. The researchers’ modeling of different courses of action caused concern, however, due to the fact that the most severe and disruptive of three strategies was described as the “only viable” approach to prevent avoidable mass deaths.
Even in the modeled case of partial measures being taken, researchers anticipated medical demand imminently surpassing “surge capacity” eight times over. They concludedthat immediate action was necessary, involving protocols described as “shocking” and “draconian” in the many news items covering the contents of their research.
Researchers’ best-outcome model — which still involved many COVID-19 deaths, but the fewest of all simulated trajectories — involved vastly reduced contact with schools and workplaces until September 2020:
Once interventions are relaxed (in the example in Figure 3, from September  onwards), infections begin to rise, resulting in a predicted peak epidemic later in the year. The more successful a strategy is at temporary suppression, the larger the later epidemic is predicted to be in the absence of vaccination, due to lesser build-up of herd immunity.
Given suppression policies may need to be maintained for many months, we examined the impact of an adaptive policy in which social distancing (plus school and university closure, if used) is only initiated after weekly confirmed case incidence in ICU patients (a group of patients highly likely to be tested) exceeds a certain “on” threshold, and is relaxed when ICU case incidence falls below a certain “off” threshold (Figure 4). Case-based policies of home isolation of symptomatic cases and household quarantine (if adopted) are continued throughout.
Further, they determined strict social distancing would need to be in force for nearly two years in order to tack to the suppression strategy described as the “only viable” approach:
The right panel of Table 4 shows that social distancing (plus school and university closure, if used) need to be in force for the majority of the 2 years of the simulation, but that the proportion of time these measures are in force is reduced for more effective interventions and for lower values of [rate of reproduction]. Table 5 shows that total deaths are reduced with lower “off” triggers; however, this also leads to longer periods during which social distancing is in place. Peak ICU demand and the proportion of time social distancing is in place are not affected by the choice of “off” trigger.
To avoid a rebound in transmission, these policies will need to be maintained until large stocks of vaccine are available to immunise the population – which could be 18 months or more [from March 2020].
The second-best approach described, one of mitigating but not suppressing transmission, involved catastrophic effects wrought on health care systems in both the UK and the United States. Perhaps most notably, “emergency surge capacity” would be exceeded even with strong anti-transmission measures put in place:
Perhaps our most significant conclusion is that mitigation is unlikely to be feasible without emergency surge capacity limits of the UK and US healthcare systems being exceeded many times over. In the most effective mitigation strategy examined, which leads to a single, relatively short epidemic (case isolation, household quarantine and social distancing of the elderly), the surge limits for both general ward and ICU beds would be exceeded by at least 8-fold under the more optimistic scenario for critical care requirements that we examined. In addition, even if all patients were able to be treated, we predict there would still be in the order of 250,000 deaths in GB, and 1.1-1.2 million in the US.
In social media discussions, “social distancing” was often framed as individuals declining recreational social contact, only leaving their homes for school, work, or supplies. Researchers addressed that notion, indicating that such measures were pointless in the scope of their simulations:
Stopping mass gatherings is predicted to have relatively little impact (results not shown) because the contact-time at such events is relatively small compared to the time spent at home, in schools or workplaces and in other community locations such as bars and restaurants.
Further to that point, researchers said that four of the five interventions must be “decisions made at the government level,” not contingent on individual decisions to go to work or school:
The other four NPIs (social distancing of those over 70 years, social distancing of the entire population, stopping mass gatherings and closure of schools and universities) are decisions made at the government level.
The second most popular r/all post on March 19 2020 (“This is what happens when you tell workers to self isolate but don’t protect their incomes”) was a striking coda to the Imperial College London COVID-19 modeling published just days before. Two days after its findings were made fully public, the image showed a crowded London Underground car presumably populated by individuals without an option to work remotely. The post’s popularity also emphasized public interest in government management of the coronavirus pandemic, as researchers made clear time to implement any measures at all was rapidly running short.