You've isolated at home for months because of the pandemic, so why are you suddenly sick? Here are a few scientific reasons why you can get sick even on lockdown.
Some of us who've had the option to stay home during the pandemic have managed to avoid more than just Covid-19. We’ve also avoided other cold and flu bugs that come with having school-age kids or working in a crowded office or just generally being human. I, for one, am dreading the onslaught of germs that will most likely find a safe haven in our out-of-practice immune systems when we return to more in-person operations.
Not everyone stuck at home has managed to escape completely illness-free.
But not everyone stuck at home has managed to escape completely illness-free. I’ve heard the same question from many friends: How am I still getting sick? I don’t do anything anymore! Where are these germs coming from?
We're (mostly) not staying home as much as we think we are
We may feel like our efforts to stay at home are complete because they represent such a drastic reduction in the activities we're used to. But the truth is that we're not really completely isolated. We likely all have that friend who says he's not venturing out when, in fact, he went for that one quick meal on a restaurant patio or ran to the mall to get some new sneakers or just met up with that one other person.
Psychologists have also documented what’s known as a “risk perception gap,” which suggests that we as a species don’t always worry about the most pressing threats. In other words, we are terrible at risk assessment, especially in the short term. So, it is likely that in most cases, the germs get in from the outside because we give them the opportunity.
Can you get sick without outside contact?
But it is also possible to make ourselves sick without an outside impetus.
Sometimes bacteria living in our body get into the wrong place and make us sick. For example, bugs like staphylococcal or streptococcal bacteria live in our nose, but if they infect our skin through an opening like a cut or a scrape? Boom! You’ve got impetigo.
And it’s not just skin infections. Ear infections, pneumonia, urinary tract infections—these are all cases of bacteria finding themselves in the wrong place.
There are some viruses that live inside us rent-free for years.
There are also some viruses that live inside us—rent-free!—for years only to be activated by periods of stress or weakened immunity. The varicella-zoster virus—that’s the virus that causes chickenpox—likes to reside in our nerve tissues around the spinal cord and the brain. The virus can be reactivated as shingles—a painful, itchy rash—if the conditions are right.
I learned this the hard way recently. After having chickenpox as a kid (there was no vaccine when I was a little) I developed shingles decades later when I was 8.5 months pregnant. The virus had found an opportunity to resurface due to the weakened immunity required by our bodies when we gestate.
How well can stress trigger illness?
In my research for this episode, I uncovered a paper written by a British Medical Officer in 1973 about an outbreak of the common cold at an Antarctic base. The twelve men had been secluded in Antarctica for seventeen weeks of what the author describes as “complete isolation” when six of them came down with colds.
The outbreak was a surprise because doctors expect any upper respiratory infections to die out and no longer be infectious after the first few weeks. Previous studies that tracked people’s antibodies during Antarctic expeditions had found influenza A and B, mumps, adenovirus, and several respiratory viruses to be completely absent in these remote groups. There was also no delivery of supplies that could have introduced new germs and thus inspire the outbreak.
So what caused the outbreak? It’s possible the virus was a stowaway in the packets of food the men brought with them and was released when the contaminated food was opened via what some call the time capsule effect. Again, complete isolation is never as complete as we think it is.
The virus may have survived in one of the men’s respiratory tracts and was potentially awoken by the stressful conditions.
But the 1973 paper authors also suggest that the virus may have survived in one of the men’s respiratory tracts and was somehow awoken, potentially by the stressful conditions related to their isolation and the extreme temperatures. The four days before the first man showed any symptoms showed a sharp decrease in the temperature which forced everyone inside.
But Antarctic extremes aren’t the only conditions stressful enough to trigger an illness. One meta-analysis that pulled together results from over 300 studies found clear links between stress and the immune system. They found that temporary stressors like deadlines at work or exams suppressed cellular immunity (that’s when our bodies use cytokines to fight the pathogens it finds on our cell surfaces) but still preserved humoral immunity (that’s when our bodies use antibodies to fight antigens in our bodily fluids.) Chronic stressors suppressed both types of immunity.
There is growing evidence for a let-down effect: We make it through a stressful event only to get sick once the imminent threat has passed.
There is also growing evidence for a let-down effect: We make it through a stressful event only to get sick once the imminent threat has passed. We have more panic attacks on the weekends, and there's evidence that decreased levels of stress can trigger migraines and asthma flare-ups.
So stress can cause fever and other illnesses, but doctors are still trying to understand exactly how. Some studies suggest the link between the two is through inflammation. When we are stressed, our body produces cortisol, the hormone that regulates our flight or fight response. If we are chronically stressed, then our body may develop a decreased sensitivity to the consistently higher levels of cortisol. But we also rely on cortisol to regulate our inflammatory response which helps us stave off disease.
As scientists work out how our bodies are able to fight certain viruses, and what conditions best set the stage for immunity, there is a similar conclusion to draw from all of these studies. Basic self-care—eating right, sleeping well, and minimizing stress as much as possible—is key to fighting off infections.