**All sources cited at the bottom of this page**

Most websites you go to for data on COVID-19 will show you a dashboard of “active” cases, the number of people who have been tested and currently have COVID-19. But because of the median 5-day incubation period (the period between exposure to the infection and the appearance of the first symptoms), the number of active cases gives us a rough indication of how many people were infected **5 days ago**. Due to this virus spreading so quickly, this number does a poor job of letting us know how many people could potentially be infected right now (and could be spreading the virus before they show symptoms). This New York Times article explains how Columbia University researchers estimate that there are 11 times more cases than have been reported.

The Covid Near Me website aims to give an **estimation **at how many people are currently infected in your state based on 1) the incubation period and 2) what we know about how quickly the virus spreads. We can use this to project how many confirmed cases we’ll see in 5 days, indicating to us how many people actually have the virus right now.

Below are more details about how this estimated active cases value is calculated.

From this research paper from March 10th and this research paper from March 17th (from UMass Amherst), we see that the median incubation period is a little over 5 days. Since most hospitals in the US are not testing people who are not showing symptoms, it’s likely that most of the confirmed cases are from people who are past this 5 day period. So to calculate an estimate of active cases **today**, we will want to take the current active cases number for your state and come up with a projection for 5 days from now.

To calculate this number, we can look at how the virus has spread so far in the US. Using the daily active values in the US from this website (all sources cited at the bottom), we can find an exponential trendline that best fits the growth pattern *so far*.

From this graph, we can see that the trendline with equation **2.61 * (e^(0.293 * x))** fits the actual growth with an R² of 99%. This isn’t exact, but it can be used to give us a *rough indication* at how quickly the virus spreads. This will undoubtedly differ drastically from state to state, so the estimated values should only be used as a rough indicator and **are by no means confirmed or guaranteed to be accurate**.

## Sources

**Sources for confirmed data (active cases, total cases, total deaths, and total recovered)**

- worldometers - which is updated whenever their data is updated (usually a few times a day). They cite their sources on that website.
- If worldometers is unavailable, the data is pulled from COVID Tracking (sources cited in line).
- Note: The recovered number is only what is reported, and very few states are correctly reporting it.

**Sources for estimated projection**

- Note: These estimates are just that, estimates. No one can perfectly predict how this virus will spread. Covid Near Me should be used as a loose indicator that applies data from the sources cited below.

- This NYT article explains that based on current projections, this virus will follow an exponential spread and peak in May (in most states).
- This research paper suggests a median 5.1 day incubation period.
- This research paper suggests that 17.9% of those infected with the virus are asymptomatic. This number is not accounted for in the estimate, but is another factor in how underreported the official “active cases” number is.
- Another great summary of the above