# Import Data from USA Fact
cases <- read.csv("https://usafactsstatic.blob.core.windows.net/public/data/covid-19/covid_confirmed_usafacts.csv")
deaths <- read.csv("https://usafactsstatic.blob.core.windows.net/public/data/covid-19/covid_deaths_usafacts.csv")

Currently, coronavirus infections are decreasing across our nation and decreasing in the state of California. As a population, it is important to maintain social distancing and continue to use masks.

Data Source

Data is pulled from USA Facts (https://usafacts.org/data/)

US Summary

As of March 14, 2021, there are 28,728,858 cases of coronavirus reported in the US and 523,267 deaths.

There are currently 8,952.68 cases per 100,000 people in the US and 163.06 deaths per 100,000 people in the US.

The average case fatality rate in the US at this point is 1.82%.

Across the US, cases are increasing at a rate of 23.41 people per 100,000 each day and deaths are increasing at a rate of 0.47 people per 100,000 each day.

California Summary

As of March 14, 2021, there are 3,516,817 cases of coronavirus reported in California and 54,892 deaths.

There are currently 9,018.88 cases per 100,000 people in California and 140.77 deaths per 100,000 people in the California

The average case fatality rate in California at this point is 1.56%.

In California, cases are increasing at a rate of 0.00 people per 100,000 each day and deaths are increasing at a rate of 0.00 people per 100,000 each day.

Current Bay Area Cases

County Population Total.Cases Total.Deaths Cases.per.100k Deaths.per.100k New.Cases.per.100k
Alameda County 1,632,747 81,701 1,311 5,003.90 80.29 0.00
City and County of San Francisco 862,004 34,688 440 4,024.11 51.04 0.00
Contra Costa County 1,123,231 63,372 713 5,641.94 63.48 0.00
Marin County 261,054 13,348 200 5,113.12 76.61 0.00
San Mateo County 763,191 39,571 525 5,184.94 68.79 0.00
Santa Clara County 1,910,105 112,103 1,835 5,868.94 96.07 0.00

** Solid grey line represents current US rates.

New Cases

New Deaths

Daily Change

Risk of Gatherings

For each gathering/sail, there is a risk of having at least 1 person that is asymptomatic but has coronavirus. This risk changes depending on the number of people in the gathering. Current research suggests that as many as 50% of novel coronavirus cases may be asymptomatic. Assuming this estimate is true, the reported case rate for a population is equivalent to the number of unreported asymptomatic cases. Knowing this information allows us to estimate the risk of encountering an asymptomatic case in a given population.

For example, in the Bay Area, there is an average of 5,139.49 reported coronavirus cases per 100,000 people. This equates to 5.14% of the population or 1 out of every 19.45718 people.

We can then use probability theory to estimate the probability that at least 1 person in a gathering of X people would be an asymptomatic coronavirus case. This estimate will vary by the number of people involved in the gathering as shown below. For example, in a gathering of 6 people, there is a 27.1% chance that at least 1 person is an asymptomatic coronavirus carrier. Or, 1 out of every 3.69 sails/boats with 6 Bay Area residents on board will have at least one person who is an asymptomatic coronavirus carrier.

Keep in mind that this is only the probability that at least one person in the group is infected and asymptomatic. This is not your probability of becoming infected. Estimates of infection risk vary widely and there are no reliable estimates for group encounters on a sailboat. My best guess estimate is that sailing contact is very similar to a household contact. In China, some studies have suggested that there is a 30-40% probability of transmission among household contacts. If this is the case, then your estimated risk of contracting coronavirus while sailing in a group of 6 is currently between 8.1% and 10.9%.

Team.Size Probability.of.Contact Number.of.Sails
2 10.0% 9.99
3 14.6% 6.83
4 19.0% 5.26
5 23.2% 4.31
6 27.1% 3.69
7 30.9% 3.24
8 34.4% 2.90
9 37.8% 2.65
10 41.0% 2.44

For a gathering of 100 people, there is a 99.8% chance that at least one person is an asymptomatic carrier of coronavirus.

AND

For a gathering of 500 people, there is a 100.0% chance that at least one person is an asymptomatic carrier of coronavirus.

Thank you