Like many people who get COVID-19, Maddy Alvarez, a 35-year-old Revere resident, can't be certain how the coronavirus got into her home. But once it did, it was uncontainable.
First, her husband Marco came down with it. He had muscle aches and a fever, but he had also experienced those symptoms just a few weeks prior. He tested negative then, so they didn’t worry too much or take any special precautions.
“It was funny because he thought he had it. He had all the symptoms, but he tested negative,” Alvarez says. “So, this time we weren’t that worried.”
Then, a few days later, Alvarez's perfume mysteriously lost its fragrance. She rushed to ask her daughters to ask if they could smell it: They could. When she walked to the polls on Election Day to cast her vote, her body began to feel heavy. It was like she was dragging weights through the wind, she says.
When she got home, the chills came on. A headache grew until she could barely think. On a work call, she put her head down. Her co-workers noticed.
“I’m starting to feel weird,” she told them.
That night, shivering uncontrollably in her bed and freaking out, she turned to her husband and said, “This is not normal. We have to get tested.”
The results were positive.
Since he was the first to fall ill, Alvarez thinks her husband, Marco, is probably the one who brought the virus into the household. But where he caught it remains a mystery. He might have been exposed while hanging out at a friend’s auto body shop. That friend later tested positive. Or perhaps it was at the grocery store or at work, or during any other small interaction in the two weeks preceding his symptoms. Or maybe he wasn’t even the one who brought the virus into their home.
But once he got sick, the coronavirus spread fast through the family. Eventually, Alvarez, her husband and two of their four children all tested positive.
As coronavirus cases surge in Massachusetts with a record 6,477 new infections reported on Thursday, health officials have been trying to get a handle on the sources of these infections, but that knowledge is hard to come by. Contact tracing provides a few clues pointing to workplaces, carpooling, small social gatherings and, above all, households.
“The household setting is number one,” says Tom Lane, the associate director of the Boston Infectious Disease Bureau. “From October 18 to November 14, out of 18,000 cases being reported, 15,000 [are linked] to the household. There doesn’t seem to be another variant as large as the household.”
Although that seems like a staggering number of cases linked to household transmission, Lane is quick to point out those connections are still based on conjecture. Even if two people in a household test positive, like Alvarez and her husband, Lane says you can’t be certain the infections are linked.
“That’s really hard to get at. Unless you are literally in a bubble, and you see nobody else except for that one person who tested positive, can we prove that you are the source of that infection?” Lane says.
That lingering doubt creates two headaches. Without knowing where people are getting infected, it’s nearly impossible to identify settings where transmission is most likely to happen. And Dr. Benjamin Linas, an epidemiologist at Boston University, says that leaves public health officials with limited interventions to stop the spread of COVID-19.
“What we’re left with is this very blunt measure of close [businesses] and stay home. That’s totally naive to the actual drivers of the epidemic,” Linas says.
For example, if officials knew that infections were mostly happening at indoor dining venues or certain types of businesses, they could target those places without shutting down the rest of the economy, Linas explains.
And as cases rise, investigators are finding it more difficult to trace superspreading events, says Bronwyn MacInnis, a genomic epidemiologist at the Broad Institute of MIT and Harvard.
“Some superspreading events are probably going undetected because it’s harder to differentiate superspreading from community transmission or clusters at all,” she says. “We’re losing the ability to follow these events up because there’s so much going on.”
MacInnis' branch of epidemiology could offer more clarity. By sequencing the genomes of the viruses that infect different people, she can see if their infections are related. With enough data and a carefully designed experiment, MacInnis says genomic epidemiology could start to unravel more of the mystery of what is driving the epidemic.
“If you have the right sampling framework, you can, in theory, start to identify sources of infection that are common – like a grocery store or gym or something along those lines,” she says.
Using genomics to get that level of detail on a large scale would take a heroic amount of data, MacInnis says. At the moment, the kind of widespread genomic surveillance effort that might be able to help solve these questions — like where Maddy Alvarez and her husband were infected — doesn’t exist.
But Alvarez says she hasn’t wondered too much about the source of the coronavirus infection that spread through her family. Having COVID alone was enough to worry about.
“It’s really hard being sick, being isolated from everybody,” she says. “You get that little depression where you just want to cry, and you know – it’s hard.”
Her husband spent a week in the hospital and needed supplemental oxygen. Luckily, she says, none of their kids developed symptoms, and she and her husband are feeling better now – though Marco is still recovering.
“He’s here at home, thank God,” she says. “He got lots better, but he’s still weak. He’s still trying to catch up with his body.”
When Alvarez speaks to Revere residents now as part of her job as a coronavirus outreach worker, she reminds them to be extra cautious, wear masks and practice social distancing – even in their own homes if someone seems to be getting sick.
“Because if you don’t?” She says and shakes her head.