Are We Battling an Unprecedented Pandemic or Panicking at a Computer-Generated Mirage?

A close look at the new study from Imperial College which models worst-case scenarios and makes the case for social distancing.

A new study generating a lot of buzz this week asks: How bad could an unmitigated COVID-19 pandemic get?

More than 80 percent of Americans would eventually be infected and about 2.2 million would die of the disease, according to the projections in a new modeling study by researchers at Imperial College (I.C.) in the United Kingdom. That implies a case-fatality rate of just over 0.8 percent. In this baseline scenario, in which no public health measures are taken, the death rate would peak at around 56,000 per day sometime around late June.

In order to prevent this dire scenario, the I.C. researchers calculate that the adoption of population-wide social distancing combined with home isolation of cases and school and university closure could cut death rates by more than 90 percent. By population-wide social distancing, the researchers mean that all households reduce their contact outside the household, school, or workplace by 75 percent. To suppress the epidemic and flatten the disease curve, these control measures would have to stay in place until a vaccine is developed and deployed in about 12 to 18 months.

"We're doomed," my Reason colleague Robby Soave argues in the event 18 months of extreme social distancing is actually what would be required to stop the coronavirus epidemic.

Doom in the financial sense is already haunting millions of small businesses as the social distancing recommendations of the Centers for Disease Control and Prevention (CDC) are implemented. The CDC urges a nationwide halt fo gatherings of more than 50 people for the next eight weeks. President Donald Trump says that gatherings should be no larger than 10 people. In an effort to reduce mass gatherings of people as a way to slow the COVID-19 epidemic, many states have ordered "non-essential" businesses such as bars, restaurants, casinos, museums, and gyms to shut down. In addition, 39 states have ordered K-12 public schools to close. The CDC also recommends that folks diagnosed with the disease and who are mildly ill to stay home.

All of these measures aim to slow down the course of the ongoing coronavirus epidemic. Will they work? Interestingly, the World Health Organization (WHO) just last year did a comprehensive review of both empirical and model simulation studies on how various non-pharmaceutical measures aimed at mitigating the effects of pandemic influenza epidemics. It is somewhat surprising how low the quality of evidence provided by many of the studies cited by the WHO researchers is. Keeping in mind that the WHO report is addressing pandemic flu, not coronavirus, what did the WHO report recommend with respect to social distancing measures?

(1) Voluntary isolation at home of sick individuals with uncomplicated illness is recommended during all influenza epidemics and pandemics, with the exception of the individuals who need to seek medical attention.

(2) Home quarantine of exposed individuals to reduce transmission is not recommended because there is no obvious rationale for this measure, and there would be considerable difficulties in implementing it. (This contradicts that I.C. study's recommendation.)

(3) Coordinated proactive school closures or class dismissals are suggested during a severe epidemic or pandemic. In such cases, the adverse effects on the community should be fully considered (e.g. family burden and economic considerations), and the timing and duration should be limited to a period that is judged to be optimal.

(4) Workplace measures (e.g. encouraging teleworking from home, staggering shifts, and loosening policies for sick leave and paid leave) are conditionally recommended, with gradation of interventions based on severity. Extreme measures such as workplace closures can be considered in extraordinarily severe pandemics in order to reduce transmission.

(5) Avoiding crowding during moderate and severe epidemics and pandemics is conditionally recommended, with the gradation of strategies linked with severity in order to increase the distance and reduce the density among populations.

One of the modeling studies cited by the WHO report finds, in a high flu transmission scenario, that a 100 percent "school closure causes a small reduction in cumulative attack rates, but a more substantial reduction in peak attack rates (of up to 40%). Such a reduction in peak incidence could mitigate stresses on healthcare systems and absenteeism in the critical workforce." That is, school closures slow down the epidemic although they do not reduce the overall number of folks who eventually become infected.

It is worth noting that the reproduction number for the pandemic 1918 Spanish flu is estimated to have been around 1.8, that is, each infected person passed the illness on to nearly two other people. The same number for seasonal flu viruses is about 1.3. It's still early in the coronavirus pandemic, but preliminary estimates suggest that 2.6 is the basic reproduction number for that disease. If that number holds up, the novel coronavirus is considerably more infectious than regular or even pandemic flu, making it that much more difficult to control.

The case for adopting the WHO report's more extreme social distancing measures strengthens with the projected severity of the pandemic disease. Are we just at the beginning of an extraordinarily severe pandemic or are we being panicked by a computer-generated mirage?

As spring arrives in the Northern Hemisphere, how lucky do you feel?