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The Math Behind Social Distancing

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The math behind social distancing

The Math Behind Social Distancing

As we wait for scientists and healthcare professionals to develop a vaccine for COVID-19, there is another, more readily available tool at our disposal.

Social distancing, defined as measures taken to reduce physical contact, is the first line of defense for containing an infectious disease like COVID-19. That’s because these infections spread when people cough, sneeze, or touch surfaces on which the virus resides.

To help us grasp the impact these measures can actually have, today’s infographic illustrates how a reduction in social exposure can theoretically contain the spread of infection.

Theoretical Potential

The calculations used to create today’s infographic come from Signer Laboratory, a stem cell research lab located in the Moores Cancer Center at the University of California San Diego.

Using a summation formula makes it possible to estimate the number of new infections over a 30 day period, across three scenarios.

Scenario5 Day Period30 Day Period
No social distancing practiced1 person infects 2.5* others406 people infected as a result
50% reduction in social exposure1 person infects 1.25* others15 people infected as a result
75% reduction in social exposure1 person infects 0.625* others2.5 people infected as a result

*For estimations only. It is not possible to infect only a fraction of another person.

To arrive at the figures reported above, Robert A.J. Signer, Ph.D., and his team made a number of key assumptions.

First, they estimated the basic reproduction number (R0) of COVID-19 to be 2.5, a figure supported by recent research. This means that, on average, an infected individual will spread the disease to 2.5 other people.

Next, they assumed that an infected individual will unknowingly spread COVID-19 over the median five day incubation period. After this period, the individual will begin to develop symptoms, immediately self quarantine, and no longer pose a threat.

Finally, they assumed a direct linear correlation between social interactions and R0. This means that when an infected person reduces their physical contact with others by 50%, they also spread the disease by an amount 50% less.

Timing is Everything

While the figures above are the results of mathematical estimations, researchers have actually studied social distancing from a variety of angles.

One study used simulations to determine the magnitude and timing of social distancing measures required to prevent a pandemic. The distancing measures simulated were:

MeasureDetails
School closureTeachers and students spent weekday daytime cycles at home, rather than at school.
Increased case isolationUpon becoming symptomatic, adults (90%) and children (100%) would self quarantine for the duration of the infection.
Workplace non-attendanceEach day, a person had a 50% chance of staying home instead of attending their workplace.
Community contact reductionIndividuals reduced their physical contact with community members by half, each day.
Combination of all fourAll four measures combined. 

The results, for a community of 30,000 people and an epidemic with R=2.5, are charted below. We can define the final illness attack rate as the share of people from an at risk population who ultimately catch the disease.

power of early social distancing

Results showed that when no action was taken, 65% of the population contracted the disease. However, if a combination of all four distancing measures were implemented instead, the attack rates were:

  • 45% (distancing begins after a 4 week delay)
  • 21% (distancing begins after a 3 week delay)
  • 7% (distancing begins after a 2 week delay)

What’s clear is that social distancing was significantly more effective when implemented with minimal delay—the final illness attack rate rose quickest beyond the third week. These findings draw a parallel to the visualizations in today’s infographic, which showed us just how quickly a disease can spread.

Social distancing interventions are important as they represent the only … measure guaranteed to be available against a novel strain of influenza in the early phases of a pandemic.

Kelso, J.K., Milne, G.J. & Kelly, H., BMC Public Health 9, 117 (2009)

We arrive at a similar conclusion when it comes to the types of distancing measures implemented. In the simulations, none of the four measures taken on their own were able to have a similar effect as when they were combined.

We All Have a Part to Play

With the global number of COVID-19 cases still rising, many governments have issued quarantine orders and travel bans.

The math supports these decisions—reducing our physical contact with others, even when we aren’t experiencing any symptoms, is crucial. Studies like the one summarized above also prove that taking action sooner, rather than later, can go a long way in reducing the spread of infection.

The key takeaway from all of this? Social distancing is a powerful disease control tool, but only if we all participate.

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China

Charting the Rise and Fall of the Global Luxury Goods Market

This infographic charts the rise and fall of the $308 billion global personal luxury market, and explores what the coming year holds for its growth

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The Rise and Fall of the Global Luxury Goods Market

Global demand for personal luxury goods has been steadily increasing for decades, resulting in an industry worth $308 billion in 2019.

However, the insatiable desire for consumers to own nice things was suddenly interrupted by the coming of COVID-19, and experts are predicting a brutal contraction of up to one-third of the current luxury good market size this year.

Will the industry bounce back? Or will it return as something noticeably different?

A Once Promising Trajectory

The global luxury goods market—which includes beauty, apparel, and accessories—has compounded at a 6% pace since the 1990s.

Recent years of growth in the personal luxury goods market can be mostly attributed to Chinese consumers. This geographic market accounted for 90% of total sales growth in 2019, followed by the Europe and the Americas.

Analysts suggest that China’s younger luxury goods consumers in particular have significant spending power, with an average spend of $6,000 (¥41,000) per person in pre-COVID times.

An Industry Now in Distress

The lethal combination of reduced foot traffic and decreased consumer spending in the first quarter of 2020 has brought the retail industry to its knees.

In fact, more than 80% of fashion and luxury players will experience financial distress as a result of extended store closures.

luxury market McKinsey supplemental

With iconic luxury retailers such as Neiman Marcus filing for bankruptcy, the pressure on the luxury industry is clear. It should be noted however, that companies who were experiencing distress before the COVID-19 outbreak will be the hardest hit.

Predicting the Collapse

In a recent report, Bain & Company estimated a 25% to 30% global luxury market contraction for the first quarter of 2020 based on several economic variables. They have also modeled three scenarios to predict the performance for the remainder of 2020.

  • Optimistic scenario: A limited market contraction of 15% to 18%, assuming increased consumer demand for the second and third quarter of the year, roughly equating to a sales decline of $46 billion to $56 billion.
  • Intermediate scenario: A moderate market contraction of between 22% and 25%, or $68 to $77 billion.
  • Worst-case scenario: A steep contraction of between 30% and 35%, equating to $92 billion to $108 billion. This assumes a longer period of sales decline.

Although there are signs of recovery in China, the industry is not expected to fully return to 2019 levels until 2022 at the earliest. By that stage, the industry could have transformed entirely.

Changing Consumer Mindsets

Since the beginning of the pandemic, one-quarter of of consumers have delayed purchasing luxury items. In fact, a portion of those who have delayed purchasing luxury goods are now considering entirely new avenues, such as seeking out cheaper alternatives.

However, most people surveyed claim that they will postpone buying luxury items until they can get a better deal on price.

luxury market supplemental

This frugal mindset could spark an interesting behavioral shift, and set the stage for a new category to emerge from the ashes—the second-hand luxury market.

Numerous sources claim that pre-owned luxury could in fact overtake the traditional luxury market, and the pandemic economy could very well be a tipping point.

The Future of Luxury

Medium-term market growth could be driven by a number of factors, from a global growing middle class and their demand for luxury products, as well as retailers’ sudden shift to e-commerce.

While analysts can only rely on predictions to determine the future of personal luxury, it is clear that the industry is at a crossroads.

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COVID-19

How U.S. Consumers are Spending Differently During COVID-19

How has COVID-19 transformed consumer spending trends so far? We look at credit and debit card spending of 5 million U.S. consumers across 18 categories.

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In 2019, nearly 70% of U.S. GDP was driven by personal consumption.

However, in the first quarter of 2020, the COVID-19 pandemic has initiated a transformation of consumer spending trends as we know them.

Consumer Spending in Charts

By leveraging new data from analytics platform 1010Data, today’s infographic dives into the credit and debit card spending of five million U.S. consumers over the past few months.

Let’s see how their spending habits have evolved over that short timeframe:

How U.S. Consumers are Spending Differently During COVID-19

The above data on consumer spending, which comes from 1010Data and powered by AI platform Exabel, is broken into 18 different categories:

  • General Merchandise & Grocery: Big Box, Pharmacy, Wholesale Club, Grocery
  • Retail: Apparel, Office Supplies, Pet Supplies
  • Restaurant: Casual dining, Fast casual, Fast food, Fine dining
  • Food Delivery: Food delivery, Grocery Delivery, Meal/Snack kit
  • Travel: Airline, Car rental, Cruise, Hotel

It’s no surprise that COVID-19 has consumers cutting back on most of their purchases, but that doesn’t mean that specific categories don’t benefit from changes in consumer habits.

Consumer Spending Changes By Category

The onset of changing consumer behavior can be observed from February 25, 2020, when compared year-over-year (YoY).

As of May 12, 2020, combined spending in all categories dropped by almost 30% YoY. Here’s how that shakes out across the different categories, across two months.

General Merchandise & Grocery

This segment saw a sharp spike in initial spending, as Americans scrambled to stockpile on non-perishable food, hand sanitizer, and toilet paper from Big Box stores like Walmart, or Wholesale Clubs like Costco.

In particular, spending on groceries reached a YoY increase of 97.1% on March 18, 2020. However, these sudden panic-buying urges leveled out by the start of April.

 Feb 25, 2020 YoY SpendingMay 5, 2020 YoY SpendingOverall Change
Big Box+14.2%-1.5%-15.7%
Grocery+1.0%+9.4%+8.4%
Pharmacy-3.6%-23.8%-20.2%
Wholesale Club+13.0%+2.6%-10.4%

Pharmaceutical purchases dropped the most in this segment, possibly as individuals cut back on their healthcare expenditures during this time. In fact, in an April 2020 McKinsey survey of physicians, 80% reported a decline in patient volumes.

Retail

With less foot traffic in malls and entire stores forced to close, sales of apparel plummeted both in physical locations and over e-commerce platforms.

 Feb 25, 2020 YoY SpendingMay 5, 2020 YoY SpendingOverall Change
Apparel-5.6%-51.9%-46.3%
Office Supplies-8.9%-2.8%+6.1%
Pet Supplies+2.7%-18.5%-21.2%

Interestingly, sales of office supplies rose as many pivoted to working from home. Many parents also likely required more of these resources to home-school their children.

Restaurant

The food and beverage industry has been hard-hit by COVID-19. While many businesses turned to delivery services to stay afloat, those in fine dining were less able to rely on such a shift, and spiraled by 88.2% by May 5, 2020, year-over-year.

 Feb 25, 2020 YoY SpendingMay 5, 2020 YoY ChangeOverall Change
Casual Dining-2.7%-64.9%-62.2%
Fast Casual4.2%-29.6%-33.8%
Fast Food2.0%-20.9%-22.9%
Fine Dining-18.6%-88.2%-69.6%

Applebees or Olive Garden exemplify casual dining, while Panera or Chipotle characterize fast casual.

Food Delivery

Meanwhile, many consumers also shifted from eating out to home cooking. As a result, grocery delivery services jumped by over five-fold—with consumers spending a whopping 558.4% more at its April 19, 2020 peak compared to last year.

 Feb. 25, 2020 YoY SpendingMay 5, 2020 YoY SpendingOverall Change
Food Delivery+18.8%+67.1%+48.3%
Grocery Delivery+23.0%+419.7%+396.7%
Meal/ Snack Kit+7.0%-5.9%-12.9%

Food delivery services are also in high demand, with Doordash seeing the highest growth in U.S. users than any other food delivery app in April.

Travel

While all travel categories experienced an immense decline, cruises suffered the worst blow by far, down by 87.0% in YoY spending since near the start of the pandemic.

 Feb 25, 2020 YoY SpendingMay 5, 2020 YoY SpendingOverall Change
Airline-7.7%-99.1%-91.4%
Car Rental-6.3%-86.0%-79.7%
Cruise-18.7%-105.7%-87.0%
Hotel-7.0%-85.9%-78.9%

Airlines have also come to a halt, nosediving by 91.4% in a 10-week span. In fact, governments worldwide have pooled together nearly $85 billion in an attempt to bail the industry out.

Hope on the Horizon?

Consumer spending offers a pulse of the economy’s health. These sharp drops in consumer spending fall in line with the steep decline in consumer confidence.

In fact, consumer confidence has eroded even more intensely than the stock market’s performance this quarter, as observed when the Index of Consumer Sentiment (ICS) is compared to the S&P 500 Index.

Consumer Sentiment Index

Many investors dumped their stocks as the coronavirus hit, but consumers tightened their purse strings even more. Yet, as the chart also shows, both the stock market and consumer sentiment are slowly but surely on the mend since April.

As the stay-at-home curtain cautiously begins to lift in the U.S., there may yet be hope for economic recovery on the horizon.

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