Risk of Community Spread

The above charts show that the seven-day averages of new COVID-19 cases are on the rise in Evanston, Suburban Cook County, Chicago, and Illinois. Each area has more than 150 new cases per 100,000 population in the last seven days. The Illinois Department of Public Health says that more than 100 cases per 100,000 indicates a risk of “substantial spread.”  The Center for Disease Control says that more than 100 cases indicates a risk of “high transmission.” [1, 2 and 3]

For test positivity in the last 7 days, IDPH uses a target of 5%. CDC says between 5% and 7.9% represents a “moderate” risk of transmission. [1, 2 and 3]

Evanston – COVID

The City reported 9 new COVID-19 cases of Evanston residents on
April 5. On April 4. there were 6 new cases, and on Saturday, April 3, there were 10.

The average number of new cases per day in the last seven days is 16.7, up from the seven-day average of 8.7 on March 29.

In the last seven days, there was a total of 117 new COVID-19 cases of Evanstonians. The 117 new cases equate to about 158 new cases per 100,000 people in the seven-day period.

The high number of new cases in the last seven days is still highly impacted by the 79 new Covid-19 cases for the three days March 30, March 31 and April 1. This high number of cases corresponds to a big jump in cases reported by Northwestern University of its staff and students for that same period. Patrick Deignan, the City’s Communications Manager, told the RoundTable that the increase reported by the City for that three-day period was due to a mix of community spread and in congregate settings, which includes cases among Northwestern students who live in dorms, etc. In the following four days there were 38 new cases.

Evanston’s case positivity rate for the last seven days is 1.7%.  

There has been a total of 4,251 COVID-19 cases of Evanston residents during the pandemic, 197 of which are active. 

No Evanstonian has died due to COVID-19 since March 4. The number of deaths due to COVID-19 remains at 114.

Impact of Northwestern University. Northwestern University has posted data on its website reporting that between March 26 and April 1, there were 81 new confirmed COVID-19 cases of NU staff (9), non-undergrad students (7), and undergrad students (65). The number includes people who live outside of Evanston. The City says it does not know how many of these cases are people who live in Evanston.  [5]

Illinois – COVID

 In the State, there were 2,102 new COVID-19 cases reported today.   

Statewide, the average number of new cases per day in the last seven days is 2,735. The seven-day average one week ago on March 29 was 2,358, so today’s number is up by 16%.

Today’s seven-day average is up from a low this year of 1,513 on March 15.  An accompanying chart shows the trend.

In the seven days ending April 5, the number of new cases per 100,000 people in the State was 151, up from 130 one week ago.

The seven-day case positivity rate for the State today is 3.8% and the test positivity rate is 4.5%.

On a Statewide basis, the number of hospitalizations due to COVID-19 was 1,581 as of midnight on April 4. This is up from 1,112 on March 15.

The number of patients using ICU beds is 385, up from 227 on March 15. The number of patients on ventilators is 159 up from 95 on March 15.

On a Statewide basis, there were 11 deaths due to COVID-19 in the last 24 hours, which brings the total to 21,384.

For the last seven days, the numbers of deaths in the State are 17, 28, 25, 24, 11, 14, and 11 today. The seven-day average is 19.

Variants in Illinois

IDPH is reporting a total of 494 confirmed cases of COVID-19 variants in the State. Of those 388 are the variant first discovered in the UK.

Vaccinations in the State

A total of 7,784,215 doses of vaccine have been delivered to providers in Illinois, including Chicago and long-term care facilities. IDPH is currently reporting that a total of 6,318,070 doses of vaccines have been administered.


1/ On Feb. 12, the CDC issued a “K-12 School Operational Strategy.” As part of that strategy, the report says, “CDC recommends the use of two measures of community burden to determine the level of risk of transmission: 1) the total number of new cases per 100,000 persons in the past 7 days; and 2) the percentage of nucleic acid amplification tests (NAATs), including RT-PCR tests that are positive during the last 7 days. The two measures of community burden should be used to assess the incidence and spread of SARS-CoV-2 in the surrounding community (e.g., county) and not in the schools themselves.” The CDC provides a chart to assess whether the risk of transmission is low, moderate, substantial, or high. The CDC recommends different types of mitigations depending on the risk level. If the two indicators suggest different levels of risk, the mitigations recommended in the higher level of risk should be implemented, says CDC. The table below, reprinted from CDC’s report, provides CDC’s Indicators and Thresholds for Community Transmission of COVID-219.

 2/ Number of Cases per 100,000 Population. On July 1, a network of research, policy and public health experts convened by Harvard’s Global Health Institute and Edmond J. Safra Center published a Key Metrics for COVID Suppression framework that provides guidance to policy makers and the public on how to target and suppress COVID-19 more effectively across the nation. The targets for new COVID-19 cases per 100,000 people are as follows (these are converted from cases per day to cases per week): a) less than 7 cases: “on track for containment;” b) 7 to 63 cases: “community spread,” rigorous test and trace program advised; c) 70 to 168 cases: “accelerated spread,” stay-at-home orders and/or rigorous test and trace programs advised; and d) 169+: ”tipping point,” stay-at-home orders necessary.  The article is available here: https://globalepidemics.org/key-metrics-for-covid-suppression/

IDPH provides these categories and ratings: 1) “minimal” – fewer than 50 cases per 100,000 in a week; 2) “moderate” – between 50 and 100 cases per week; and 3) “substantial” more than 100 cases per 100,000 in a week.  In its Metrics for School Determination of Community Spread, IDPH says the “target” is 50 cases per week per 100,000 people.

3/ The Test Positivity Rate. In addition, on May 26, Johns Hopkins University & Medicine Coronavirus Resource Center said on its website that “the World Health Organization (WHO) advised governments [on May 15] that before reopening, rates of positivity in testing (i.e., out of all tests conducted, how many came back positive for COVID-19) should remain at 5% or lower for at least 14 days.”  Link: https://coronavirus.jhu.edu/testing/testing-positivity

The Harvard Global Health Institute (HGHI) says, “A network of research, policy, and public health organizations convened by Harvard and MIT called the TTSI Collaborative has agreed on a 3% test positive rate or below as a key indicator of progress towards suppression level testing.”

IDPH says the test positivity target is 5% or less. IDPH provides these categories and ratings: 1) “Minimal” – test positivity rate is equal to or less than 5%: 2) “Moderate” – test positivity rate is between 5% and 8%; and 3) “Substantial” – test positivity rate is over 8%. In its Metrics for School Determination of Community Spread, IDPH says the target is 5%.

4/ Calculations. The RoundTable calculates the number of cases per 100,000 using case data provided by IDPH and assuming that the population of Suburban Cook County is 2.469 million, that the population of Chicago is 2.710 million, and that the population of Illinois is 12.671 million.

5/ Northwestern University COVID-19 Cases. Ike C. Ogbo, Director of Evanston’s Health & Human Services Department, told the RoundTable that the COVID-19 cases reported by the City include cases of faculty, staff, and students attending Northwestern University who live in Evanston. The RoundTable asked the City in an FOIA Request to provide the number of NU students who tested positive for COVID-19 and who live in Evanston. The City refused to provide the data. On Oct. 26, the RoundTable appealed the City’s decision to the Public Access Counselor of the Attorney General’s Office. On Nov. 13, the City filed a response claiming it does not have any records showing the number of NU students who tested positive for COVID-19 and who live in Evanston.

The RoundTable has asked Northwestern University on several occasions to provide information breaking out the number of new COVID-19 cases of its faculty, staff and students by residency in Evanston. NU did not respond.

Larry Gavin

Larry Gavin was a co-founder of the Evanston RoundTable in 1998 and assisted in its conversion to a non-profit in 2021. He has received many journalism awards for his articles on education, housing and...