Yes, the summer cold and cough season really is worse than usual.

"I've had bad colds, but I've never experienced a virus like this," said Holly Riddel, 55, an entrepreneur in Redondo Beach, California, who has been suffering from congestion, clogged ears and a raspy throat for about two weeks. "I want this gone. I haven't been able to work out. I'm just not feeling like myself."

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, Texas, in late June to visit friends. Although she is fully vaccinated against COVID-19, she took multiple tests to be sure she was not 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," Wehrman said. "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.

Although your immune system is likely as strong as it always was, if it has not been alerted to a microbial intruder in a while, it may take a bit longer to get revved up when challenged by a pathogen again, experts say. And while some viral exposures in our past have conferred lasting immunity, other illnesses may have given us only transient immunity that waned as we were isolating at home.

"Frequent exposure to various pathogens primes or jazzes up the immune system to be ready to respond to that pathogen," said Dr. Paul Skolnik, an immunovirologist and chair of internal medicine at the Virginia Tech Carilion School of Medicine. "If you've not had those exposures, your immune system may be a little slower to respond or doesn't respond as fully, leading to greater susceptibility to some respiratory infections and sometimes longer or more protracted symptoms."

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 spokesperson at the CDC, which plans to release a report this week 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 may 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.

"We're seeing each other again and sharing our viruses, and I think maybe we are all a little more susceptible to viruses we haven't seen," Edwards said. "To know exactly what each person has is hard to say. In adults, the symptoms by and large are the same, and you can't tell if it's RSV, rhinovirus, parainfluenza or another cold virus."

Dr. Satya Dandekar, an expert in viral infections and mucosal immunology, said that while isolation measures did not weaken our immune system, other factors, including stress, poor sleep habits and increased alcohol consumption, could play a role in how an individual immune system responds to a respiratory virus.

"There is going to be a tremendous variable response in the community for who is going to respond and deal with infections well and who will get sick," said Dandekar, chair of the department of medical microbiology and immunology at the University of California-Davis School of Medicine. "When a person gets exposed to a pathogen, there has to be a rapid ramp-up of the response from the immune system and immune cells. With stress and other factors, the army of immune cells is a little hampered and slows down and may not be able to react fast enough to attack, giving enough time for the pathogen to get a hold on the host."

Dr. Allison Agwu, an infectious disease specialist at Johns Hopkins Children's Center, said that even though many pandemic restrictions have been loosened, people should be mindful about taking precautions to prevent the spread of all respiratory illnesses.

"Do the things we tell fifth graders: Wash your hands, cover your sneeze, get rest, all those things," Agwu said. "And do your best to get vaccinated against the things you can. Get your COVID vaccine so you're less paranoid when you get a cold."

The higher rate of RSV and other respiratory viruses this summer was largely predicted in a paper last winter published in the Proceedings of the National Academy of Sciences. But what is not clear is when the flu virus will reemerge and what effect it will have. Rachel Baker, the study's lead author and a public health researcher and research scholar at Princeton University, said a potential worry will be if the flu, RSV and COVID-19 all circulate at the same time.

"The big puzzle is, where is the flu?" Baker said. "I think it's a very uncertain flu season. It's not necessarily going to be worse, but when is it going to come back? And what is it going to look like?"

Baker noted that she is currently struggling with her own summer cold, which she assumes she picked up when she ventured out to a local pub to watch the recent England vs. Italy soccer match, which she felt safe doing after being fully vaccinated against COVID-19.

"This was a very crowded pub, everyone was shouting at the TV, and no one was wearing a mask apart from me," she said. "I tried to stand near the door for better circulation. A few days later I got the cold. I can't believe I wrote the paper on this, and I got the summertime cold."