COVID-19/coronavirus is spreading through the world. The WHO classifies it as a pandemic (source), and the United States has declared a national emergency because of it (source).

Data on the infection rate is difficult to find. This post will present some data sources and show some visualizations of the infections. It’ll also provide some tips on how to avoid coronavirus.

This post will be updated frequently (hopefully daily).

Let’s visualize the First, let’s visualize the fraction of people that are infected in each country. The very useful data sources are mentioned in the appendix.

This is frightening on 2020-03-141 It looks like the US health care system will be overrun in early April. Hopefully the infection rate slows before that can happen. How can we aid the infection slowing down?

Slowing the rate of infection

Right now (2020-03-14) it seems that the only hope is social distancing. I think the timeline for a vaccine is too long (around 18 months), and cures/therapeutic drugs aren’t here yet (though they’re coming). Here are some resources to help with social distancing:

In short, avoid social contact as much as possible. The biggest tips are to work from home and avoid large crowds. Social distancing is why so many sporting events have been canceled and so many universities are canceling class.

The positive effect of immediate and extreme social distancing is best illustrated with the 1918 flu epidemic/the Spanish flu. The hardest hit city was Philadelphia. The infection hit the city very suddenly, meaning the health care system was quickly saturated and overrun. One effect of this: they had to stack bodies on the sidewalk because the morgues were overflowing (source).

However, St. Louis practiced immediate and extreme social distancing when the flu hit the city. Just 2 days after the flu hit the civilian population, Dr. Max Starkloff quickly ordered the closer of schools, movie theaters, sporting events and public gatherings.2

This meant the flu spread much more slowly throughout St. Louis than Philadelphia. Here’s a graph of the death rate for the two cities2

Functionally, the time taken to start social distancing is the only difference between these two curves. St. Louis responded about 14 days quicker than Philadelphia. That meant St. Louis had half the total death rate of Philadelphia, and they didn’t have to pile bodies on the streets because their morgues were too full.

The difference between these two cities is discussed more in these two articles:

How fast is the virus spreading?

The direct visualization of this is with the number of new cases each day:

This perhaps isn’t the best visualization; it’s pretty noisy, and there’s no information about the retired population or the quality/size of the health care system. Here’s a different visualization:

It appears the number of confirmed cases is doubling every 2.4 days before the infection gets under control3 (as with South Korea and Italy). Details on the back-of-the-envelope calculation are in the appendix; briefly, I take the number of cases required to Italy’s health care system and scale by the population that’s 65 years or older and number of hospital beds.

This looks to be rather scary for the U.K. The Prime Minister Boris Johnson has largely kept the UK open. Schools and universities have been kept open far too long, and many businesses and citizens didn’t take coronavirus seriously (source). For example, on March 12th the government said it didn’t want to “disrupt daily life before it was absolutely necessary”.4 It looks like the UK will have more deaths and a higher economic cost.5

How fast is the virus spreading in the US?

How many infections does the US have? When will the number of people who need hospitalization overwhelm the number of hospital beds?

If social distancing does not work and no medicine is developed, it looks like this virus will overwhelm the health care system sometime in late March.

How fast is the US spreading in each state?

In most states, it appears the number of confirmed coronavirus cases is growing more slowly on 2020-03-31!

These tests are confounded by testing. On 2020-03-22, it looks like New York is rapidly expanding testing, or the virus is spreading faster. I believe they’re expanding testing – they recently opened a drive-thru testing facility (source), and NY has about 8× the number of cases as WA but only 1.2× the number of deaths (on 2020-03-22).

I interpret the increase in testing to be finding cases earlier in the infection cycle and/or discovering the infection in unconcerned populations (e.g., college students), especially because I doubt the virus can spread faster than doubling once every 2.4 days. The increased testing is likely masking the effect I’m concerned about, the load on the health care system.

It appears New York City is a hotspot, and confounded by testing. Regardless if that’s the case, let’s generate the same plot but without the data from New York6:

It looks like the infections in the US are starting to slow down, presuming that NY is doing more testing. If true, that’s great news! A couple points:

  • Social distancing is working! The effect we’re seeing is probably from 5–10 days previous, so March 11th–16th on 2020-03-21. That’s right when the US started social distancing.
  • If it continues, social distancing has bought the US at least 4 days, probably 5 before the health care system saturates. That’s 4× fewer total cases!

How serious are people about social distancing?

Let’s study a weak proxy for this question, the number of restaurant reservations bookings through OpenTable:

Here’s a visualization of the subway usage in New York City:

For an interactive version of this graph, visit the New York City Subway Usage Dashboard by Todd Schneider.


U.K.’s approach

On March 12th, the U.K. goverment said that their approach…

include[d] asking people with even [a] very mild cough and flu symptoms to stay home, but stopped short of the measures seen in most other European countries and increasingly in North America, including closing schools and colleges.

The government said Thursday [March 12th] that it may have to impose these more stringent measures at some point in the future, but that doing so now would be premature, disrupting daily life before it was absolutely necessary, and risking the public would grow tired of complying with the restrictions and begin to ignore them just when the peak number of infections might be expected ….

—”Even while canceling mass gatherings, the U.K. is still aiming for deliberate ‘herd immunity’”. Fortune, March 14th.

They waited 6 days until March 18th before they “disrupted daily life”. It looks like they waited too long – 6 days means 5.6× more cases because the infection doubles every 2.4 days. That’d be bad even if they had a quality health care system; however, I estimate the U.K.’s health care system can handle 5× fewer patients than the US health care system.

Health care breakdown estimation

The number of infections I estimate each country can handle comes from Italy’s health care system being overrun, which happened when the had approximately 12,500 cases when their health care system reached capacity. I scale each countries infection density by the percent of the population over 65 and the number of “critical care beds”. This is a back-of-the-envelope calculation that only relies on all health care systems being equally capable.

To estimate the number of cases each country can handle, I use this equation:

# Measures how much greater concentration the given country can handle
ratio = (frac_over_65 / italy_frac_over_65) * (n_beds / italy_beds)

# Scale by population
limit = ratio * (pop / italy_pop) * italy_cases_breakdown


If you’re interested, I’ve published a page with all the images in this post without any text.

Data sources

My visualizations are geared towards to the US because I live there. If you’d like to customize this plot, I encourage you to download and customize the plots in the following notebooks:

Data sources include the following:

COVID-19 kills older people more often. 99% of the deaths are for people that are 50 or older. That’s not to say younger people who contract the virus does not have impacts: “some recovered patients may have reduced lung function and are left gasping for air while walking briskly” (source).

Here’s the fraction of each countries population that is over 65:

Here are the number on critical care beds per capita (source):

The Wikipedia page on “2020 coronavirus pandemic in the United States” also has this graph.

“Health care saturation” dates:

Social distancing dates:

  • Italy: Feb. 25th, chosen because on that day the following happening in Italy:
    • Morgan Stanley, Barclays, Mediobanca and UniCredit requested their employees work from home.
    • The University of Palermo suspended all activities.
    • The Italian Basketball Federation suspended all of its championship games.
    • The Italian stock index (FTSE MID) fell by 6%.
    • (Feb. 23rd) Last two days of the Carnival of Venice are cancelled
    • (Feb. 24th) The Basilicata instituted a 14-day mandatory quarantine for people arriving from Northern Italy
  • US: March 12th because the following happened in the US:
    • On March 11th or 12th, many universities announced canceled class would be canceled or held online when the students returned from Spring Break (including Cornell, Harvard, USC, UMN and UW–Madison).
    • On March 11th, Google, Facebook, Microsoft and E3 announced their technology conferences would be held online. Apple announced their technology conference would be moved online on March 13th.
    • On March 12th, The NHL, MLS and Women’s Soccer League announced they would cancel their season.
    • On March 12th, the NCAA announced it would cancel March Madness. 2020 is the first year in it’s 81-year history that it will not be held.
  • UK: March 19th because on March 18th, 19th and 20th the following happened in the UK:
    • On March 18th, McDonald’s and others “announced that they would not permit customers to sit and eat in stores”
    • On March 18th, many schools announced all university buildings would be closed to students and staff on March 20th (that Friday), including Welsh, Scottish and Northern Ireland K-12 schools and Cambridge University (detail).
    • On March 19th, a Sheffield light rail network and Yorkshire bus operators announced a reduced timetable

For the restaurant bookings chart, I used the data from OpenTable’s “The state of the restaurant industry

  1. It’s been frightening since I first started plotting it on March 9th. 

  2. Public health interventions and epidemic intensity during the 1918 influenza pandemic” by Richard J. Hatchett, Carter E. Mecher, and Marc Lipsitch. 2007. (the chart I show is a modification of fig. 1).  2

  3. China first reported the virus doubled every 6.2 days (source). Either China is lying or the virus becoming more virulent as it ages. 

  4. From an article published March 14th in Fortune. More context for the quote is shown in the appendix 

  5. I can’t estimate the amount (on 2020-03-21). 

  6. And (naively) scaling the beds/ventilators.