Were summer colds up in 2021?

Question

The article Why Everyone Has the Worst Summer Cold Ever by the New York Times suggests that there is some expectation of a bad cold season.

The U.S. Centers for Disease Control and Prevention says that cases of common respiratory viruses, including respiratory syncytial virus (RSV) and human parainfluenza viruses, which cause typical cold and flu symptoms, are on the rise this summer. The spike in RSV, which can be especially risky to the very young and very old, is particularly unusual for this time of year, said a representative of the CDC, which released a report late in June about the pandemic's effect on a variety of respiratory viruses. The surge in RSV was most notable in several southern states, but the virus has begun to crop up all over the country. Its spread has been tracked primarily in young children, some of whom have been hospitalized with severe symptoms.

The RSV surge, which has been seen in Europe, South Africa, Australia and New Zealand as well, is likely the result of pandemic lockdowns, which created a much larger population of susceptible young children. A cohort of babies, now toddlers, were largely protected from the virus when few of us were out and about. Since then, a new group of infants has been born — giving the virus the opportunity to infect roughly twice as many vulnerable children and creating more vectors to spread it to older children and adults, who typically have milder symptoms. [...]

While doctors might test young children to confirm a case of RSV, and many people who have cold symptoms will be tested to rule out covid-19, most people probably will not know the specific respiratory virus causing their symptoms, said Dr. Kathryn M. Edwards, professor of pediatrics at Vanderbilt University Medical Center.

Given how infectious COVID is, the more parsimonious explanation for the supposed rise in colds is that vaccinated people get milder COVID and the sensitivity of COVID testing is low. Furthermore, I do not believe that it is common practice to confirm a suspected common cold with PCR. It seems possible to me that the default diagnosis for a mild breakthrough COVID case with a negative lab is the common cold, despite COVID potentially being more likely.

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In particular, according to The National Respiratory and Enteric Virus Surveillance System (NREVSS), RSV cases seem to be approaching 2019 levels, with perhaps no indication of falling off. These data are adequately explained (both the absolute number of detected cases, and the test positivity rate) by massively increased testing of all respiratory conditions and also the conditioning of RSV tests upon negative Covid/flu tests. This convolution already makes it impossible to compare the humps of this graph reliably, but the complete lack of demographic data and hospitalizations makes it impossible to speculate about how the conditional testing might affect outcomes. Furthermore, the primary cause of the spread of RSV is school being open, which is not yet the case in the majority of the US, and certainly hasn't been the case for long enough to matter. I'm open to being wrong about this, but it seems to me that the data necessary to discriminate between a disproprotionate and seasonally misaligned RSV outbreak and the aforementioned explanation is completely missing. Furthermore, as part of their softer journalism, the author has this to say:

Months of pandemic restrictions aimed at Covid-19 had the unintended but welcome effect of stopping flu, cold and other viruses from spreading. But now that masks are off and social gatherings, hugs and handshakes are back, the run-of-the-mill viruses that cause drippy noses, stuffy heads, coughs and sneezes have also returned with a vengeance.

“It was a bad chest cold — chest congestion, a rattling cough,” said Laura Wehrman, 52, a wardrobe supervisor for film and television, who caught a weeklong bug after flying to New York from Austin in late June to visit friends. Although she’s fully vaccinated against Covid-19, she took multiple tests to be sure she wasn’t infected. Eventually a doctor confirmed it was a rhinovirus, a common cold virus. She said several of her other friends also have been sick with colds and coughs as well.

“I was staying with one of my best friends, and it got tense for a minute because she had started a new job, and she didn’t want to be sick,” said Ms. Wehrman. “I actually went and checked into a hotel for the last two days so I could just cough away by myself.”

Infectious disease experts say there are a number of factors fueling this hot, sneezy summer. While pandemic lockdowns protected many people from Covid-19, our immune systems missed the daily workout of being exposed to a multitude of microbes back when we commuted on subways, spent time at the office, gathered with friends and sent children to day care and school.

Note the use of the past tense, and the implication that the subject's friends who have respiratory symptoms possess similar evidence that they do not have covid, despite very clearly being speculation.

Answer 1

TL;DR; There are too many unknowns and insufficient testing to say definitively, but it’s likely based on previous evidence. Although not for a common reason that's often talked about.

I also think it's worth noting

The virus responsible for the COVID-19 pandemic, SARS-CoV-2, is part of a large family of coronaviruses. Coronaviruses usually cause mild to moderate upper-respiratory tract illnesses, like the common cold. However, SARS-CoV-2 can cause serious illness and even death. Why people’s COVID-19 symptoms vary so greatly isn’t fully understood.

Source: nih.gov

Coronaviruses account for ~20% of all 'common cold' cases in a year, every year. There's evidence if you've had specific mutations of other coronaviruses in the past your immune cells are better prepared for COVID-19 - one common theory for asymptomatic individuals. Obviously most wouldn't group COVID-19 with a common cold (some will), but if you do because of the similar symptoms (with COVID-19's being FAR more severe), cold cases have certainly increased.

Now, separating COVID-19 from other common cold viruses, yes, there is still precedent to make this claim.

Part 1 - Typical Adult Population

Immunologists have long known that isolation generally weakens our immune systems. However it may not be for the reason most often heard. Rather than a lack of exposure to germs the weakening of the immune system comes from increased stressed, anxiety, loneliness, and/or a general lack of "social connectedness". You can find reports of that here:

Your immune system remembers that germ; if it ever appears again, your body can quickly manufacture the appropriate antibodies again. (The immune system has many other protective effects as well, including targeting cancer cells for destruction.) Reducing your exposure to germs cannot alter this process. Your immune system will not suddenly “forget” what a particular germ looks like just because you aren’t exposing yourself to it regularly.

followed by

Germs aren’t the only thing that affects your immune system. Stress can exert a negative effect on your immune system’s ability to function optimally. Mental stress causes your internal inflammation levels to rise as your body releases various hormones to cope. Inflammation, in turn, impairs the immune system’s ability to mount a defense against any germs it encounters.

And also from this MIT article, linking to other evidence:

I’ve been hearing people say that staying home and social distancing is harming our immune systems. The reasoning is that if we don’t come into contact with many germs, our immune systems weaken. This means that once we all start coming out of the house more, we’ll be more susceptible to colds and flu and even the new COVID-19 illness. Is this true?

We’ve been hearing this theory too, and we can assure you that this is NOT the way your immune system works.

Followed by:

Research shows that our anti-viral response is suppressed when we feel lonely. An analysis of 148 different studies involving more than 300,000 people found that people who were more socially connected were 50 percent less likely to die over a given period. One experiment even found that people with many social ties are less susceptible to the common cold.

For more of the same:

Although adults and older children can breathe a sigh of relief knowing that their immune systems will remember how to fight off microbes, there is another piece of this puzzle to consider: stress.

Researchers Fulvio D’Acquisto and Alice Hamilton, who published a review in the journal Cardiovascular Research, note that while physical distancing “minimizes the spread of COVID-19, such social isolation has the potential to affect the cardiovascular and immune systems.”

There is also evidence that some recovered COVID-19 patients have a weakened immune system long after 'recovering'

So yes, there is reason to believe the cold season will be worse than previous years - but luckily it's no need for concern - these strains of the coronavirus, rhinovirus, RSV, parainfluenza, and the unknowns that cause the common cold rarely cause serious complications.

While cases of the common cold are rarely tracked well enough to say definitively (many are never reported/no doctor visit required), and given an estimate of 1 billion cold cases experienced by US citizens each year, it's going to be hard to say definitively if this year is worse or not empirically. It's also nearly impossible to gauge the differences in severity or length of a 'trivial' viral infection. But there is plenty of evidence it should/will be.

Part 2 - The Differences For Children

Sadly, the answer is less pleasant for the youngest among us. Anyone still in their developmental years probably has a weaker immune system than their historic peers. Both for lack of exposure, and the same reasons listed for adults above.

Further, of the aforementioned 1 billion annual cases, a vast majority occur in children.

Children have about 6 to 10 colds a year. One important reason why colds are so common in children is because they are often in close contact with each other in daycare centers and schools. In families with children in school, the number of colds per child can be as high as 12 a year. Adults average about 2 to 4 colds a year.

The good news is, this problem is relatively benign. While this year will most likely lead to high rates of infection, the curve should normalize relatively shortly. But we should expect to see more of the spike in cold cases to come from colds in children than colds in adults.

There are also a litany of at least decently reputable publications offering the same opinion, typically citing expert opinion in the piece. 1, 2, 3, 4, 5

And from the fifth link above, to reiterate the assurance from medical professionals:

“As the general population becomes vaccinated and we are able to open up again, these young children will have plenty of opportunity for their immune systems to become exposed to and make antibodies to common childhood cold viruses,” Bandi said.

So again, while yes, there will likely be a worse cold season this year for children, it's not really worth the worry (and the stress of worrying may make you more likely to catch a cold! So go out and live life, worry about a cold if/when you catch one). The only way to get things back to normal are to deal with the (arguably negligible) consequences that have stemmed from social distancing measures over the last ~year.