How the coronavirus manifests symptomatically in St. Clair County patients may not stand out too differently from other regions.

But health officials said more people are likely asymptomatic than local residents may realize.

A recent report from the county health department included a clinical list of symptoms, breaking down the percentage of which have been present among all cases reported in the area thus far.

As of Aug. 6, common symptoms like fever, cough and fatigue had been reported in 69, 68 and 62% of all cases in St. Clair County, respectively. About 14% of cases — there were 842 reported in total as of Friday and 803 the Friday prior — were reported to be asymptomatic, meaning they showed no symptoms.

Dr. Annette Mercatante, the county’s medical health officer, said the number of people affected without symptoms is “just the tip of the iceberg,” and that people may feel sick but not attribute it to the virus.

“It’s what’s visual to us,” she said. “We have to understand that there’s a whole lot of stuff going on that we’re not capturing.”

“It would suggest that the asymptomatic rate is actually considerably higher than that,” Mercatante added.

The county puts out a report on local coronavirus numbers every Friday, and Mercatante said they included the list of symptoms in the Aug. 6 update after a member of the public asked about the subject in a recent question-and-answer session, which are held virtually every Thursday.

Other symptoms were present in local COVID-19 cases, as follows:

• 59%: Muscle aches (myalgia)
• 54%: Headaches
• 47%: Chills or rigors
• 43%: Shortness of breath (dyspnea)
• 39%: Congestion (coryza)
• 36%: Sore throat
• 35%: Loss of taste or smell
• 33%: Runny nose (rhinorrhea)
• 30%: Diarrhea
• 24%: Nausea or vomiting
• 13%: Evidence of pneumonia
• 12%: Abdominal pain
• 3%: Acute Respiratory Distress Syndrome
• 1%: Toxic state (sepsis)

What do symptoms say about how infectious the virus can get?

Denise Parr, an infection prevention nurse with Lake Huron Medical Center, said St. Clair County has done well in response to the virus but is at risk of its proximity to more populous areas in southeast Michigan, where case rates are higher.

And that may reflect some minor differences in reported symptoms — or the lack thereof.

Mercatante said asymptomatic rates are reportedly lower outside the county. She said that could be because testing is more focused on symptomatic patients in other areas.

Despite data that can be skewed by testing, she said it’s clear many more are asymptomatic just as there are likely more coronavirus cases active at any time in general. 

“It depends on what you read, but I’ve read anywhere from 20 to 40% of the cases can be asymptomatic,” Mercatante said.

The county makes information available if residents are looking for more on how to get tested for COVID-19 through its website.

Those affected can spread the virus up to 48 hours before showing symptoms, and those exposed are commonly encouraged to monitor for them up to two weeks.

Parr said they were also seeing “multiple cases where COVID positive” patients continued to be positive with polymerase chain reaction testing, which a fast detection method, “up to 30 days after the first symptom or test result.”

“Scientific evidence shows (the) concentration of the virus decline after symptom onset,” she said. “Up to 88% of the test subjects had no replicable virus after 10 days and in 15 days 95%. The caution is with immunocompromised and severely ill who may be infectious up to 20 days.”

COVID-19 prevent will also help stave off the flu

Parr said that at an infection prevention meeting Thursday, which consisted of both hospital personnel and Mercatante, they discussed the possibility of a sporadic case rate instead of a large second surge of the coronavirus.

“This doesn’t mean we stop following precautions because we are entering influenza season,” she said via email later that day. “My hope is the community continues to mask, social distance and isolate at home when ill to reduce the numbers of influenza and COVID-19 cases this fall.”

Parr said many of the flu symptoms are similar in COVID and it can take time for someone’s physician to diagnose the difference.

Earlier in 2020, she said flu numbers were trending higher this year than last before the pandemic it.

“We are heading into flu season (again) and one thing we saw in the spring was, as soon as people started washing their hands, social distancing and wearing masks, the flu numbers dropped dramatically,” Parr said. Basic prevention steps for the coronavirus “may protect you from influenza as well.”

Some positive COVID cases have manifested with single symptoms like diarrhea, but Parr said most exhibit “the classics.”

“What strikes me is a broad range of symptoms,” Mercatante said. “I guess it’s typical of a lot of viral syndromes, but people have to realize that mild allergy symptoms could, in fact, be a symptom of COVID. If we’re serious about trying to identify these things — and you know, and do our contact tracing and get to that, so they’re not spreading — people have to be aggressive about (taking the right steps).”

Contact Jackie Smith at (810) 989-6270 or [email protected]. Follow her on Twitter @Jackie20Smith.  

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