TagCOVID spread

We visualized COVID’s spread across every U.S. state and county. Here’s what we discovered:

Just by looking at numbers and daily updates, it can be hard to decipher a clear narrative of how COVID has affected the U.S. and its diverse regions over time. 

To give you a better understanding, our team at Covid Act Now took all of the data we’ve been collecting and created a time-lapse of COVID’s spread across 3,000+ U.S. counties since March. Watch what happens:

Notice anything interesting? Here are 5 key patterns that our team saw:

1. More movement = higher COVID incidence.

Mobility data, or data relating to transportation, show a striking similarity between the percentage of people staying home and cases per 100,000 people (also known as incidence) during the month of August (source: U.S. Bureau of Transportation Statistics).

Especially in the Southeast (which includes states like Alabama, Arkansas, Florida, Georgia, Kentucky, Louisiana, and Mississippi), only 5 percent to 10 percent of people are consistently staying home, and this is reflected in their red case density values:

2.Masks and other non-pharmaceutical interventions (NPIs) play a powerful role in controlling the spread of the virus.

As America’s viral epicenter, New York pioneered NPIs for COVID prevention. Starting on April 17, Gov. Andrew Cuomo enacted a mask requirement, and this, in addition to other NPIs in New York State, contributed to New York’s eventual containment of COVID (source: New York State). Some of New York’s NPIs include:

March 15: Schools close for the first time.March 28: New York State’s 2020 democratic primary is postponed to limit in-person social contact.April 16: Stay-at-home order and school closures are extended through May 15.April 22: Cuomo announces plans to begin a localized contact tracing program throughout New York State.

From this animation of New York, we can see the success of these policies in limiting the virus from March to June.

3. NPIs not only reduce the spread of COVID within states but also between them.

Throughout the animation, it is clear that COVID spreads rapidly within states, often going from a few red counties to an entire red state within weeks, not months.

The border between Arizona and New Mexico, however, is an example of how COVID oftentimes meets a metaphorical wall at state borders. With the Arizona side of the border solidly red in late July, New Mexico was able to maintain a handle on the virus.

The difference in COVID cases in the two states can be attributed to differing statewide policies:

Masks:New Mexico institutes a statewide mask requirement on May 16, with harsh monetary penalties for mask infractions (source: State of New Mexico).In contrast, Arizona, despite having some of the highest case density in the country, still only “recommends” mask wearing. In fact, until June 17,  Gov. Doug Ducey does not allow local governments to introduce mask mandates (source: Office of the Governor of Arizona).Quick response to outbreaks:It takes until July 9, after Arizona’s cases reach record highs and hospitals reach capacity, for Gov.Ducey to reduce restaurant dine-in services to 50 percent capacity.In comparison, indoor dining is not allowed in New Mexico until June 1, and Gov. Michelle Lujan Grisham quickly passes an executive order in July as Arizona’s cases spike, outlawing indoor dining, closing state parks to out-of-state visitors, and requiring masks while exercising.

The disparity in cases is well reflected in July, when Arizona (left) is almost entirely red, while New Mexico (right) has much more yellow and green:

4. Relaxing NPIs too early leads to flare-ups of COVID.

Let’s look at Georgia as an example here. Although Georgia initially implemented NPIs, such as stay-at-home orders and school closures, several premature reopening policies may have led to further outbreaks in the state. Let’s look at the timeline:

April 24-27: Gov. Brian Kemp allows the reopening of restaurants (including indoor dining), movie theaters, gyms, and more (Georgia ACLU).August 15: Gov. Kemp does not allow local governments (such as Atlanta) to create mask mandates until August 15. Up until this point, there are no mask mandates on either the state or local level. However, only cities and counties that have 19 or more cases per 100,000 people may enact mask requirements for public property. For reference, at 19 or more cases per 100,000, our animation displays dark orange. August 20: University of Georgia and Georgia Tech reopen for in-person classes.

These failures to maintain effective NPIs are reflected in the difference in Georgia between April (left) and August (right) where you can see the number of counties in the red go from approximately 25 percent to 90 percent:

5. When critical safety measures are taken, large, outdoor gatherings may not result in a spike in cases.

While many were concerned that the recent protests and gatherings for social justice would lead to a spike in COVID cases, our map shows that this was in fact not the case. The New York Times produced this map on June 6, when protesting peaked, showing where protests happened geographically:

Via the New York Times, “Black Lives Matter May Be the Largest Movement in U.S. History”

Regions that saw protests include California’s Bay Area and Los Angeles County, New York and Washington DC, and Minnesota/Wisconsin.

If the protests had caused outbreaks, the animation would have displayed meaningful color changes in regions that hosted large protests and gatherings. The lack of outbreaks demonstrates that if we take proper precautions, large gatherings that take place outdoors may not be as dangerous as we once thought.

Symptoms of COVID usually show up two to 14 days after infection (source: CDC). If the protests caused a spike in cases, we would have detected the increase in about two weeks. However, in all of the regions listed above, there was no spike after June 6. See screenshots from June 5 and two weeks later below:

By comparing state and local policies (including mask mandates, school closures, restrictions on indoor dining and other NPIs) to the geographic spread of COVID, a clear picture emerges of how COVID can be contained when society takes action. What’s more, our video depicts visually how states that lift stay-at-home mandates and other restrictions prematurely experience rapid flare-ups of COVID. In contrast, states that keep NPIs in place are even able to stop COVID from crossing their state border.

Check out our  Youtube Channel for our educational videos.

To learn more about Covid Act Now, visit our about page. For more information please reach out on our contact page or by email at info@covidactnow.org.

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Infection Rate: Explained

The Infection Rate, or “R(t),” is the number of people one infected person goes on to infect in a specific area, over a specific time. The areas we look at are county and state. The period of time we look at is while a person is contagious (able to spread COVID).

In the picture to the right, R(t) is 3.

If the R(t) is 3, one person will most likely infect three other people, and those three people will each go on to infect three more people and so forth.

R(t) is one of the most important metrics Covid Act Now tracks because it tells us how fast COVID is spreading. R(t), in combination with daily new cases, tells us about how many people are spreading COVID and at what rate. R(t) also indicates risks associated with ICU headroom used.

Here is a video that helps explain infection rate:

R(t) can change based on factors like community behavior (whether there are large gatherings) and their intervention practices (whether people wear masks and maintain social distancing.) 

How Does Covid Act Now rate R(t)?

We use 0.9 as the cutoff for a green score because, at 0.9, the number of infected people significantly declines. This is because each infected person is spreading COVID to less than one other person. 

When looking at R(t), it is important to note both value and direction. In the graph above, on March 31, the R(t) value was critical, but decreasing. On June 7, the R(t) value was high and increasing.

**The dotted line on the right represents values that have yet to be finalized.

There are significant delays between when people change their behavior and when that behavior change is reflected in R(t). When people are infected, it takes time to develop symptoms, get tested, and receive results. Because of these delays, interventions like social distancing or mask orders will take at least a few days, if not weeks, to show a decrease in R(t).

Similarly, by the time you see cases rise in your county or state, COVID has likely been spreading for days or weeks. The lower test positivity is, the more accurate R(t) measurements are because the state or county is missing fewer positive cases.

Where does our data come from for this metric?

To calculate R(t), we use new positive cases and COVID death data from The New York Times.

Infection rate is just one of several important metrics to determine how well your state or county is doing in the fight against COVID. Learn more about daily new cases, test positivity, ICU headroom used, and contact tracing. For a description of assumptions and methodology, please see our references and assumptions document, along with our data sources presentation.

Check out our Youtube Channel for our educational videos.

To learn more about Covid Act Now, visit our about page. For more information please reach out on our contact page or by email at info@covidactnow.org.

Sign up to our alerts to stay up-to-date on the COVID risk level in your area.

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