Recent COVID surges, research proves importance of ‘Swiss Cheese Model’

If you’ve been hearing that COVID is back, that’s mostly true. 

COVID infections and hospitalizations have indeed been on the rise throughout the country this month, closing schools and prompting a number of healthcare systems, companies and colleges to bring back masking mandates meant to protect the public from passing or catching the SARS-CoV-2 virus that causes the disease known as COVID-19.

So, yes, COVID is on the rise, but we can’t say “it’s back” because, in truth, it never went away.

As MIT Technology Review pointed out in July: “A couple of months ago, the WHO declared that covid was no longer a public health emergency of international concern. Which sounds great, until you realize it’s because it is now “an established and ongoing health issue.”

COVID will never disappear just because we’re sick of taking precautions against it and wish it would go away.  In fact, this type of wishful thinking and ducking our collective heads in the sand is more likely to endanger our communities. 

Repeatedly being infected with COVID “is akin to playing Russian roulette,” the program director at the Forrest General Hospital Family Medicine Residency Program recently told the American Medical Association. “It can be problematic if you are reinfected (with SARS-CoV-2). We know from a pretty elegant study that was recently published in Nature Medicine that each subsequent COVID infection will increase your risk of developing chronic health issues like diabetes, kidney disease, organ failure and even mental health problems.”

The evidence on COVID reinfections — which can happen even if you’re fully vaccinated against the virus — the doctor said, “dispels the myth that repeated brushes with the virus are mild and you don’t have to worry about it.”

Research on SARS-C0V-2 and COVID is constantly proving this is a virus capable of not only wreaking short-term havoc on our bodies in its acute phase, but also of causing some pretty severe long-term health complications. 

When we hear our friends or family members tell us COVID is “just the flu” or “just a cold,” we have to remember that there is a whole body of research that proves otherwise.

So, what do we actually know about COVID? 

As far back as August 2021, we knew that being diagnosed with COVID raised one’s risk of heart attacks and stroke. As the Harvard Health Letter pointed out in November 2022: “In one of the largest studies of its kind to date, researchers found strong evidence that heart attack and stroke risk rises sharply in the weeks following a COVID diagnosis. The findings were published Aug. 14, 2021, in The Lancet. … In the week after a COVID diagnosis, the risk of a first heart attack increased by three to eight times. The risk of a first stroke caused by a blood clot multiplied by three to six times. In the following weeks, both risks decreased steadily but stayed elevated for at least a month.”

“Other bacterial and viral infections (such as influenza) are known to temporarily boost rates of heart attacks and strokes,” the Harvard journal added. “But COVID infections appear to be especially risky, perhaps because they trigger an exaggerated inflammatory response that makes blood clots more likely.”

Even before that, in 2020, we knew that children played a much greater role in spreading COVID to the greater community. As one researcher told The Harvard Gazette in 2020 about children spreading COVID: “I was not expecting the viral load to be so high. You think of a hospital, and of all of the precautions taken to treat severely ill adults, but the viral loads of these hospitalized patients are significantly lower than a ‘healthy child’ who is walking around with a high SARS-CoV-2 viral load.”

The Canadian Medical Association told us in August 2021, that “even mild COVID may have long-term brain impacts,” and pointed to a British study of more than 81,000 people that found “those who previously had COVID tended to score lower on measures of intelligence, reasoning, problem-solving and planning than people who were never infected.”

In 2022, we learned this COVID-induced stroke risk impacts even young, previously very healthy people.  As the University of Utah pointed out in January 2022: “The COVID pandemic has been unpredictable as more is learned about the varied side effects of the virus. A typical respiratory infection, such as the flu, usually has a specific set of symptoms and potential complications. With COVID, the long-term effects range from neurological complications to loss of taste and smell, trouble focusing (“brain fog”), and chronic fatigue. Another surprising finding from several studies is the heightened risk of stroke and heart attack—and not just for older adults. People under the age of 50 appear to be at much higher risk of these complications too.”

We also discovered in 2022, that, when it comes to heart damage from COVID, the disease doesn’t discriminate: “Until now, people who suffered mild or asymptomatic COVID were thought to have dodged the brunt of the virus’s brutal side effects,” Johns Hopkins Bloomberg School of Public Health stated on March 14, 2022. “But new evidence has revealed that anyone infected with COVID is at higher risk for heart issues—including clots, inflammation, and arrhythmias — a risk that persists even in relatively healthy people long after the illness has passed.”

And, perhaps most disappointing to everyone who had such high hopes for the vaccines — which have proven to be, at least temporarily, effective at preventing severe acute COVID – we learned in May 2022, that the COVID vaccines “offer little protection against long COVID.” 

In fact, when it comes to “long COVID,” it’s important to remember what that really means for people. In September 2022, Time magazine warned: “Long COVID experts and advocates say the government is ignoring ‘the greatest mass-disabling event in human history.’”

In fact, as reported by PBS in April 2023, “long COVID symptoms are keeping many Americans from returning to work,” with as many as four million people in the U.S. now reporting that long COVID has “significantly reduced their ability to carry out day-to-day activities.”

Northwestern Medicine pointed out in 2022 that long COVID “occurs in approximately one-third of COVID-19 survivors and, in 2022, was estimated to be the third leading neurologic disorder in the United States.”

Additionally, a Northwestern Medicine study found that more than 8 out of 10 people with long COVID-19 experience four or more neurologic symptoms that impact quality of life and cognitive abilities up to 15 months after having the disease.

Another Northwestern Medicine study of nearly 2,000 long-COVID patients, published in May 2022, showed that “85% of patients reported decreased quality of life; 51% had cognitive impairment; 45% had altered lung function; 83% had abnormal CT chest scans; (and)12% had elevated heart rate on rhythm monitoring.”

A more recent study, published March 3, 2023, in JAMA Health Forum, showed that long-COVID patients have an increased risk of death and serious health problems compared to people who had never been infected by SARS-CoV-2. 

More recent research shows that a previous infection with the Omicron variety of SARS-CoV-2 may make people more susceptible to reinfection with an Omicron subvariant. A study published in The Lancet this week stated: “It is unclear whether hybrid immunity (combined vaccination and infection) after one Omicron infection provides increased protection against subsequent Omicron reinfection in older adults.” 

And though, for some inexplicable reason, our latest public health guidance seems to emphasize washing our hands over wearing a quality mask, we also know SARS-CoV-2 is indeed an airborne virus. Here is how the U.S. Environmental Protection Agency describes it: “Spread of COVID-19 occurs via airborne particles and droplets. People who are infected with COVID can release particles and droplets of respiratory fluids that contain the SARS CoV-2 virus into the air when they exhale (e.g., quiet breathing, speaking, singing, exercise, coughing, sneezing). The droplets or aerosol particles vary across a wide range of sizes – from visible to microscopic. Once infectious droplets and particles are exhaled, they move outward from the person. These droplets carry the virus and transmit infection. Indoors, the very fine droplets and particles will continue to spread through the air in the room or space and can accumulate.”

“Since (COVID) is transmitted through contact with respiratory fluids carrying the infectious SARS-CoV-2 virus, a person can be exposed by an infected person coughing or speaking near them,” the EPA states on its website. “They can also be exposed by inhaling aerosol particles that are spreading away from the infected person. Transmission of (COVID) from inhalation of virus in the air can occur at distances greater than six feet. Particles from an infected person can move throughout an entire room or indoor space. The particles can also linger in the air after a person has left the room – they can remain airborne for hours in some cases. Someone can also be exposed via splashes and sprays of respiratory fluids directly onto their mucous membranes. Spread may also sometimes occur through contact with contaminated surfaces, though this route is now considered less likely.”

The important part of that is that SARS-CoV-2 particles “can linger in the air after a person has left the room … for hours in some cases.” This is the reason community-wide masking — particularly in healthcare settings where people who are most vulnerable to dying from COVID or becoming increasingly ill, including many cancer patients and those already suffering debilitating symptoms of long-COVID — is so important to protecting ourselves and each other. 

When public health leaders decided to take away mask mandates, even in hospitals, they told us they would bring them back if community spread started to ramp back up. Unfortunately, once they’d dismantled the testing centers and low-cost at-home testing, and told people, “The pandemic is over!” knowing that a community surge was ramping up became nearly impossible. 

Luckily, there are still quite a few wastewater testing sites around the nation, including in Clark County, that have been able to act as an early warning for those of us who want to see a surge coming before hospitals are overrun with very sick patients and more young people are exposed to a virus that can cause possibly lifelong complications. 

Wastewater testing in the U.S. shows COVID infections have been ramping up since July. The data showed an average of 165 copies of the virus per milliliter (mL). On Wednesday, Aug. 30, that number was up to 554 copies/mL — as high as it was during a COVID surge in the winter of 2023. The wastewater data also shows that the lowest community spread of COVID occurred during the spring and summer of 2020, when many public-facing businesses were still shut down, and again during the summer of 2021, following mass vaccinations and previous to the Omicron variant that could seemingly break through our vaccine-induced and natural immunity. In both of those cases, the wastewater COVID levels were between 40 and 80 copies/mL. In March 2022, post-Omicron surge, the levels hit another low of 111 copies/mL. Despite all the talk of the pandemic being “over,” the wastewater levels have not dipped under 111 copies/mL since then. In fact, they spiked past 1,000 copies/mL in July 2022 and again in December 2022. 

We know through wastewater testing that COVID is still circulating and has been ramping up for at least the past month. But, thanks to some pretty abysmal public health messaging, many people truly believe they don’t have to worry about being infected by SARS-CoV-2 anymore. 

In reality, because this virus keeps mutating and devising ways of slipping through our lines of defense, we never should have given up on the most basic protections, including masking in public; staying home when we’re ill; avoiding huge crowds (even outdoors); and investing in air-cleaning systems that can rapidly reduce the viral load in public buildings like hospitals, schools, churches and workplaces, as well as in our own homes. 

So what can we do, now that COVID, armed with new variants that may be able to get past our vaccine-induced and natural immunity, seems to be surging again? 

We can remember the Swiss Cheese Model of risk reduction, which tells us that layers of protection will always be better than relying on just vaccines or washing out hands. To truly protect ourselves, our families, friends and entire communities from the ongoing threat of COVID, we need to engage in a variety of protections on an individual level — wearing respirator-style masks (an N95 mask, for instance, instead of surgical-style or cloth masks) in public indoor or crowded outdoor spaces; washing our hands; staying home when we feel ill; testing to see if we have COVID when we show symptoms (which can change depending on the variant); and isolating when we do test positive — as well as on a societal level, such as bringing back mask mandates during surges; mandatory clean air initiatives; low-cost, easily accessible vaccines; and providing fast, accurate testing for everyone. 

We cannot wish COVID away, but we can all do our part to take individual precautions and to encourage our public officials to implement public health safety precautions during surges to help protect our community’s most vulnerable and to prevent even one more community member from dying of this disease or from developing long COVID.

To learn more about preventing COVID in your own home and in your community, visit: health.harvard.edu/diseases-and-conditions/preventing-the-spread-of-the-coronavirus.