It started late 2021 with some tongue-in-cheek Tweets about bad Amazon reviews for Yankee Candles. 

Could they be a canary in the coal mind for a COVID surge to come? 

Northeastern University Assistant Professor and Researcher Nick Beauchamp was curious.  

He'd been looking at social media impacting COVID-19 data. His next hypothesis included the COVID symptom of anosmia, aka loss of smell.  

"I downloaded a bunch of review data, counted up the references to no smell or no scent and sort of shared a plot of that curve, which indeed matches the COVID curve," Beauchamp said.   

He then looked beyond candles, adding perfume reviews to the data and eventually publishing his findings.

"I try, in the project, to sort of check to see whether it holds for perfume. Yeah, it does hold for perfume ... Does it hold for flu? No, it doesn't hold for flu. Does it work even when you control for the sort of seasonality of both COVID and candle purchases and complaints? Yes, it seems to survive that," Beauchamp continued. 

His 2021 results, COVID cases predicted negative reviews but negative reviews did not predict cases.

SEE MORE: COVID-19 Survivors Still Dealing With Lingering Symptoms

"It's possible, or plausible, that the rise in complaints was actually due to COVID, you know, with all the usual caveats, but that the reviews themselves were not super good at giving us a heads up on when cases were rising," Beauchamp said.

He ran the numbers again June 2022 and found bad reviews went out and then cases went up.  

Beauchamp has visited the numbers again this month. He says so far, in October, the bad reviews have been on the rise for the past two months, cases have stayed flat or declined over the same period.  

Important to note: Case tracking has been impacted by factors like at-home testing. The CDC has also moved from daily case and death counts to weekly ones. 

Health experts are predicting a modest fall and winter wave, going off current case increases in Europe.   

Meanwhile, Beauchamp says the candle data is just interesting and funny, nothing more. But the research has impacted how his family thinks about health.

"We haven't taken to sniffing candles to test ourselves, but, you know, we are fairly cautious—and I think, probably because I spend time working on this—more cautious than the average household," he said.

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If you haven’t experienced it yourself, you probably know someone who lost their sense of taste or smell from COVID-19.

“This virus has receptors including the ACE-2 that it binds to. And the ACE-2 receptor is particularly found in the olfactory epithelium, which are the areas the cells in the nose, deep inside the nose where the sense of smell fibers descend down from the brain,” said Dr. Carol Yan, a Rhinologist at UC San Diego.

She has been working with patients who have a loss of taste and smell from COVID-19.

“We’ve known for many years that all viruses have the potential to cause smell loss, and it is, in particular with this virus, that we’ve seen a much higher incidence of smell and taste loss,” said Dr. Yan.

We haven’t known until recently that the loss of smell, at least in the case of COVID, might be tied to your genetics.

“We compared people who had COVID-19 who did have a loss of smell versus people who didn’t, and we found a very clear genetic association with that particular symptom,” said Janie Shelton, an epidemiologist with 23&Me.

In a recent study, the company claims it can identify the genetic trait linked to the loss of smell in COVID patients.

“When we looked across all the chromosomes in the genome, we saw one really particular region in the genome that appeared to be strongly associated with loss of smell and so that region of the genome governs the expression of enzymes in your nose that clear smells out of your nose,” Shelton said.

If you’re like me, you’re probably wondering which types of people have this trait. But Shelton says it’s not that simple.

“What we saw was that this was relevant across all the different race-ethnic groups that we had in our sample,” said Shelton.

So, anyone can have this genetic trait. They still don’t know what may cause long-term loss of smell in people.

“Those people, you know we don’t really know why they specifically haven’t recovered and whether or not there’s a genetic component to that an immuno component or something different,” said Dr. Yan.

But 23&Me is looking into that next.

“Of the people who reported COVID to us, we went back and asked them to fill out another web-based survey about whether or not they’ve had symptoms of long COVID,” said Shelton.

Hoping to uncover more answers for the people suffering from long-term symptoms.

A new study has found evidence that SARS-CoV-2, the virus that causes COVID-19, infects the cells in the mouth including the salivary glands — which may explain some COVID-19 symptoms such as loss of taste and dry mouth.

The findings of the study led by the U.S. National Institutes of Health (NIH) and the University of North Carolina at Chapel Hill also “point to the possibility that the mouth plays a role in transmitting SARS-CoV-2 to the lungs or digestive system via saliva laden with the virus from infected oral cells,” according to a press release.

The study, published in Nature Medicine, focused on discovering where SARS-CoV-2 in the saliva comes from as it is well established that people diagnosed with COVID-19 contain high levels of the virus in their saliva.

People with COVID-19 who have respiratory symptoms may have the virus in their saliva from nasal drainage of sputum coughed up from the lungs, the release states, but the researchers said it may not explain how the virus gets into the saliva of people who lack those symptoms.

Blake Warner, lead study author and assistant clinical director and chief of the National Institute of Dental and Craniofacial Research (NIDCR), said in the release that “based on the data from our laboratories, we suspected at least some of the virus in saliva could be coming from infected tissues in the mouth itself.”

To investigate this, scientists surveyed oral tissue collected from healthy people in order to identify mouth regions susceptible to SARS-CoV-2 infection. The vulnerable cells contained ribonucleic acid (RNA) molecules that have instructions for making “entry proteins” or “doorways” that the virus needs to be able to get into the cells and infect it.

RNA for two key entry proteins known as the ACE2 receptor and the TMPRSS2 enzyme were found in cells of the salivary glands and in tissues lining the oral cavity, which indicated “increased vulnerability because the virus is thought to need both entry proteins to gain access to cells,” the release states.

Warner said that those factors are similar to the ones found in regions known to be susceptible to SARS-CoV-2 infection, such as the lining of the nasal passage and upper airways.

The next step for the researchers after confirming that parts of the mouth are susceptible to SARS-CoV-2 was to look for evidence of infection in oral tissue samples from people with COVID-19. In samples collected at the NIH from COVID-19 patients who had died, SARS-CoV-2 RNA was found in “just over half” of the salivary glands examined. Researchers also found the specific sequences of RNA that indicated cells were actively making new copies of the virus in a living person who had acute COVID-19.

The study further found that salivary gland tissue infected with SARS-CoV-2 could be the source of the virus in saliva. In people with mild or asymptomatic COVID-19, cells shed from the mouth into saliva were found to have the RNA entry proteins and SARS-CoV-2 RNA.

In order to determine whether virus found in saliva is infectious, researchers took saliva from eight people with asymptomatic COVID-19 and exposed it to healthy cells grown in a dish.

Saliva from two of the eight subjects led to infection of the healthy cells – raising the possibility that asymptomatic COVID-19 patients might transmit infectious SARS-CoV-2 to others through saliva, according to the study.

A final aspect of the study was to explore the relationship between oral symptoms of COVID-19 and virus in saliva. Researchers collected saliva from a group of 35 volunteers with mild or asymptomatic COVID-19. Of the 27 people who were experiencing oral symptoms, those with the virus in their saliva were more likely to report loss of taste and smell, suggesting that oral infection might underlie oral symptoms of COVID-19.

The study’s findings suggest that the mouth, via infected oral tissue cells, plays a bigger role in SARS-CoV-2 infections than previously thought.

“When infected saliva is swallowed or tiny particles of it are inhaled, we think it can potentially transmit SARS-CoV-2 further into our throats, our lungs, or even our lungs,” said Kevin Byrd, second author of the study and assistant professor in dentistry at the University of North Carolina Chapel Hill, in the release.

The researchers hope to confirm their findings in a larger group of people and to determine the exact nature of the part the mouth plays in SARS-CoV-2 infection and transmission, according to the release.

"By revealing a potentially underappreciated role for the oral cavity in SARS-CoV-2 infection, our study could open up new investigative avenues leading to a better understanding of the course of infection and disease. Such information could also inform interventions to combat the virus and alleviate oral symptoms of COVID-19," Warner said.