MILWAUKEE — In recent months, the scientific world has seen a steady flow of research updating what we know about the novel coronavirus, SARS-CoV-2, and how it affects humans. Because the virus is so new, researchers are still grappling with many questions about its function. And because of the nature of the scientific process, no single study can completely answer those questions. Instead, new research is constantly challenging our understanding of the pandemic.

Here, we explore some recent studies that have shed new light on the virus. 

Shorter exposures to infected people may add up

When thinking about how an infected person can spread the coronavirus to another, we’ve mainly focused on single, prolonged interactions. But according to a case study and new Centers for Disease Control and Prevention guidance, several shorter interactions might also be enough to pass the virus on. 

On Wednesday, the CDC updated its definition of who counts as “close contacts” of a confirmed COVID-19 case — the people who should get tested and quarantine for two weeks. The previous definition only included those who had spent 15 consecutive minutes within 6 feet of an infected person. Now, though, the definition includes those who get close for “a cumulative total of 15 minutes or more over a 24-hour period,” not necessarily all in one stretch.

It’s a small but significant change, meaning even short breaks from social distancing may build up to an infection. And it broadens the scope of the people that contact tracers should be notifying about potential exposures.

This new understanding is supported by a study out of a Vermont correctional facility. A correctional officer there appears to have contracted COVID-19 after a series of short interactions with six incarcerated people who later tested positive for the virus.

Each separate encounter was quick — just one minute on average, according to video footage reviewed in the study — but the officer spent an estimated 17 minutes within the 6-foot range over the course of his shift. About a week later, he started experiencing symptoms and tested positive for COVID-19, even though he wasn’t originally identified as a close contact for the infected inmates.

Because the officer didn’t report any other known exposures and community spread is low in the area, the researchers conclude that “his most likely exposures occurred in the correctional facility through multiple brief encounters.”

Like many things in this pandemic, the 15-minute guidance isn’t a hard-and-fast rule to begin with, but more of a guideline to think about the amount of virus a person is being exposed to. That’s important because experts think the amount of virus you take in can determine whether you contract COVID-19 at all — and, possibly, how sick you get from the disease.

Other factors also play into how much virus gets transferred: Mask-wearing and ventilation can help cut down the potential exchange, for example. But the case of this officer — who was wearing a cloth mask, gown, and goggles during his interactions with inmates — highlights that any close contact with a COVID-19 patient may be risky.

“This change underscores the importance of vigilant social distancing,” Caitlin Rivers, an epidemiologist at the Johns Hopkins Center for Health Security, tells The Washington Post. “Even multiple brief interactions can pose a risk.”

CDC reports 300,000 excess deaths — higher than the official COVID-19 toll

The COVID-19 pandemic may be causing even more deaths than the official toll captures, according to CDC data.

Almost 300,000 more Americans have died this year than in a normal year, CDC researchers report. That’s significantly higher than the official toll for coronavirus deaths, which this week surpassed 220,000 in the United States. 

As the researchers write, the disparity means one important thing: Our official counts “might underestimate the total impact of the pandemic on mortality.”

The study looks at this year’s total reported deaths — not just those among COVID-19 patients — between January and October and compares those numbers to the same time period in recent years. 

Stacked up against the average numbers between 2015 and 2019, there were 299,028 “excess deaths” this year. The confirmed COVID-19 toll only captures about two-thirds of those deaths.

“The number of people dying from this pandemic is higher than we think,” Steven Woolf, director emeritus of the Center on Society and Health at Virginia Commonwealth University, tells The Washington Post. “This study shows it. Others have as well.”

Woolf led another study on excess deaths between March and April, with a similar finding that the COVID-19 death toll only captured about two-thirds of excess deaths. 

Some of the extra deaths could include COVID-19 cases that go undocumented due to delayed reporting or misattributed cause of death, Woolf and the other authors write. They may also be indirect results of the pandemic’s wide-reaching disruptions — casualties caused by “delayed care for acute emergencies, exacerbations of chronic diseases, and psychological distress (eg, drug overdoses),” among other factors.

No matter the cause, this year’s excess deaths have hit minority communities the hardest, according to the CDC study. Latino people saw a 53.6% rise in total deaths, the highest of any group. Asian, Black, American Indian, and Alaska Native groups all saw much higher increases than white people — who still saw an 11.9% rise in deaths.

And out of any age group, younger adults aged 25 to 44 saw the biggest rise in mortality, with a 26.5% overall increase from recent years.

In hospitals, COVID-19 patients are five times more likely to die than flu patients

A patient hospitalized with COVID-19 is much more likely to die or face severe complications than one hospitalized with the flu, according to a new CDC study.

Researchers used hospital records from the national Veterans Health Administration — the largest integrated health care system in the U.S. — to compare outcomes for around 4,000 coronavirus patients and 5,500 influenza patients.

Compared to the flu patients, the COVID-19 patients had a five times greater risk of dying in the hospital, the study finds. Only 3.8% of flu patients died in the hospital, compared to 21% of coronavirus patients.

The COVID-19 patients were about twice as likely to be admitted to intensive care and stayed in the hospital for about twice as long.

Coronavirus also increased patients’ risk of developing 17 different complications affecting the respiratory system and other parts of the body. Pneumonia, respiratory failure, acute kidney failure, and stroke were all more common among COVID-19 patients — in line with findings that continue to show the virus attacks more than just the lungs.

And again, ethnic minority groups faced more complications, with Black and Latino patients faring worse than white patients even after adjusting for age and underlying conditions. The study “provides further evidence that certain racial and ethnic minority groups are disproportionately affected by COVID-19,” its authors write.

The CDC report highlights that, while the flu remains a serious problem, COVID-19 represents a greater threat to those whose cases are severe enough to land them in the hospital. In the 2018 to 2019 flu season, estimates show that around 34,000 Americans died, which represents about 15% of the official COVID-19 toll so far. 

Some medical trials stuck on pause, but others forge ahead in race for vaccine

Across the world, scientists continue the race to develop effective vaccines and treatments for COVID-19. The New York Times reports that 48 vaccines are currently being tested out on humans, and 12 of them are in large-scale Phase 3 trials.

Some promising trials have been put on hold recently due to various health concerns among participants — though experts have stressed that this is a normal step in human trials and a sign that companies are serious about vaccine safety. 

Johnson & Johnson put its clinical trial on hold last week after an “unexplained illness” arose in one of the study’s participants. Drugmaker Eli Lilly also paused its trial of a monoclonal antibody treatment — an immune system-boosting infusion similar to the one President Trump received — because of a “potential safety concern.”

AstraZeneca’s Phase 3 trial, which included UW Health as one of its testing sites, was paused in September due to a suspected adverse reaction in one of its participants. It has since started back up in other countries and is reportedly gearing up to restart in the U.S. — even as Brazilian health authorities reported Wednesday that a volunteer in the trials there had died. 

Experts say the volunteer probably received a placebo and not the vaccine itself, in which case the death would not be a result of the vaccine.

“This due diligence is important,” cardiologist Adrian Hernandez writes in STAT News about these pauses. “It tells the American public that everyone is committed not just to developing new treatments, but to developing ones that are safe and effective.”

As some of these trials remain sidelined, though, a group of UK researchers is making plans to fast-track vaccine development by intentionally infecting healthy volunteers with COVID-19.

Scientists at Imperial College London hope to complete what’s known as a “human challenge study,” planning to infect 90 healthy volunteers with the virus starting in January — pending approval from ethics committees and regulators. 

They’d first administer small doses of the virus to unvaccinated volunteers, in this way figuring out just how much virus it takes for someone to get sick, as The New York Times reports. From there, researchers would give the newly developed vaccine to volunteers and expose them to the same amount of virus to see if they’re protected from infection.

The human challenge setup is controversial, but would save valuable time: Other vaccine trials involve a lot of waiting around to see whether vaccinated participants come in contact with the virus in their everyday lives. In a pandemic that continues to claim thousands of lives by the day, some say the risk is worth it.

“Every day that goes on, more cases are going on, more people are dying,” Danica Marcos, who has already volunteered for the study, tells the Associated Press. “And if this vaccine trial could mean that this period of trauma for the whole world will be over sooner, I want to help. I want to be a part of that.”