Chicago's coronavirus cases are rising and so are tests, but city officials say the current surge can't be explained by a simple increase in testing.
Chicago Department of Public Health Commissioner Dr. Allison Arwady said the increase in testing doesn't equate to the increase in cases.
"Testing continues to increase in Chicago, yes, but the numbers of tests needed to identify one case is decreasing," Arwady said Monday.
She called it a "warning sign" for the city that the number of people who must be tested to find a single coronavirus case is decreasing.
"Ideally, as your tests are going up, you're doing more, you're needing to test more and more people to find a single case. So what we see here just in the last week, while the number of tests continued to go up, but the number that we needed to test to find one case was going down, we know that it's not all testing," Arwady said.
The city's test positivity rate has climbed back above 5%.
"We worked really hard all summer, it was the main thing holding us back that we could not get the test positivity under 5%," Arwady said. "And now in just a week, we've seen that progress reverse itself. We're now at 5.4% positivity citywide and some ZIP codes are much higher."
But the idea that increased testing is behind recent spikes in cases in Chicago wasn't the only coronavirus-related myth Arwady debunked Monday.
She also addressed what is behind the spread of cases, the death rates and masks.
What is behind the latest spread of coronavirus in Chicago?
Despite common beliefs that public spaces are largely where coronavirus spread is occurring, Chicago officials say recent trends show a shift toward in-home transmission.
"Two out of three Chicagoans diagnosed with COVID-19 tell us that they know the person who likely infected them," Arwady said. "People worry a lot about being out and about in crowds, on the CTA, walking down the street, and it is absolutely possible to be infected. But I will tell you, it is not what we see driving infection. Even transit systems around the world have not been shown to be the major sign of spread that we expected they might be. And I think that is because when people are on transit, they're thinking about COVID, they're wearing their mask, they're trying to keep their distance, they're washing their hands, because by nature, we worry more about people we do not know."
But recent data has shown that spread from close contacts within homes has been driving the latest spikes.
"Where we see the spread of COVID is where we let down our guard, where we literally let down our mask, because we feel comfortable with those we love," Arwady said. "But the virus is just looking for opportunities to spread. And Chicagoans also tell us that three out of four of these close interactions took place at home."
Arwady urged residents to not invite anyone into their homes or apartments or hold any non-essential gatherings.
Do masks prevent coronavirus?
According to Arwady, "scientists agree that masks work."
"Masks absolutely decrease your chance of spreading COVID to others," Arwady said. "There is even emerging data that they may serve some role in helping to protect you from getting COVID. There's some interesting animal models that suggest they may reduce the severity of disease if you do get infected because fewer viral particles can get in masks do not harm you."
Arwady cited a recent report from Nature, a British scientific journal, which looked at the efficacy of wearing masks.
She also noted a study out of the University of New South Wales in Australia, which compared a sneeze through varying degrees of masks.
In the study, images showed germs in the air from someone who is not wearing a mask, someone who is wearing a one-layer cloth mask such as a T-shirt, someone who is wearing a two-layer cloth mask, and someone who is wearing a surgical mask. The images showed those wearing any version of a mask saw fewer germs spread during a sneeze than the person without.
The Mayo Clinic also published a report that "cloth masks reduce the number of respiratory droplets a person releases into the air when talking, sneezing or coughing."
"When you wear this, you stop germs from leaving your mouth," Arwady said. "Not 100% of the time, but it is one of the easiest things you can do to protect those you love and to protect Chicago."
According to the Centers for Disease Control and Prevention, the guidance for wearing a mask "is based on what we know about the role respiratory droplets play in the spread of the virus that causes COVID-19, paired with emerging evidence from clinical and laboratory studies that shows masks reduce the spray of droplets when worn over the nose and mouth."
"COVID-19 spreads mainly among people who are in close contact with one another (within about 6 feet), so the use of masks is particularly important in settings where people are close to each other or where social distancing is difficult to maintain."
Arwady addressed other common objections people have to wearing masks, saying they do not drop oxygen levels or raise carbon dioxide levels.
According to the WHO, masks may reduce your ability to breathe, and therefore people should not wear them while running, biking, walking, and so on. Instead, you should try to maintain a safe distance from other people. It's important to note, however, that exercising is the only circumstance in which a mask is not recommended.
It also does not spread COVID-19 or make the wearer more susceptible, Arwady said.
"It cannot give you COVID," she said. "It does not make you more likely to get COVID."
How a mask is worn also matters, Arwady said.
"It should cover both your mouth and your nose," Arwady said. "I see a lot of people, and I know you do too, wearing their mask, moving their mask under their chin or just over their mouth...mouth and nose."
But, Arwady said, masks are only part of the plan.
"It is only one strategy. It's one of the most important ones, but you need to wear your mask and also watch your distance and also wash your hands," she said.
How many people are dying of coronavirus?
"If you hear people saying we don't have to worry about COVID because people are not getting seriously ill, they're not getting admitted to the hospital, they're not dying - please don't believe that," Arwady said.
While the recent spike in coronavirus cases has not led to a major spike in deaths or hospitalizations, Chicago medical experts say an increase is likely to follow.
"We have not yet seen major increases in hospitalizations, we have not yet seen major increases in ICU, we have not yet seen major increases in people on the ventilator or people dying, but that is because those indicators take time to show up," Arwady said. "The cases rise first and then unfortunately, we start to see these increases."
As of Monday, Chicago was seeing a 7-day rolling average of 508 new cases per day, according to the city's coronavirus data dashboard. That marks a significant increase from the roughly 300 new cases per day rolling average the city was seeing just three weeks earlier when restrictions were eased.
The numbers also coincide with a 25% increase in non-ICU COVID-19 hospitalizations since Sept. 22, according to city data.
Dr. Nancy Glick, an infectious disease specialist with the Sinai Health System, reported the healthcare system is starting to see a rise in cases.
"Until about two weeks ago, the numbers had been pretty low and we were really not seeing many cases," Glick said Monday. "Two weeks ago, things changed. We now have restarted our multidisciplinary COVID round teams every day to make sure that people are being monitored and getting the best treatment possible. We have seen multiple people from the same family, the same household, coming to the hospital ill with COVID-19, requiring hospitalization. This can be devastating to patients and families who may have one member of their family in the intensive care unit, another member of the family and the medical unit but unable to see each other. As a health care worker, it is difficult to see this research. I think a lot of us in the health care system...were overwhelmed by the first wave of COVID. And to see it starting up again, is really scary."
Arwady warned that while the numbers haven't caught up with a rise in cases yet, she believes a spike is coming.
"If we're not able to turn things around, I unfortunately fully expect to see even the more serious outcomes following on in the next few weeks," she said.