For months, Canadians have been bubbling up with other friends and family to socialize safely during the pandemic.But with COVID-19 case counts rising in many communities, kids back in schools and more people returning to work, many public health experts agree that what worked as a safe approach in the early days of the lockdown now comes with more risk."I honestly think with the return to school right now, most people's bubbles have burst," says epidemiologist Ashleigh Tuite. "You're talking about large numbers of connections."In Ontario, "social circles" allow you to see up to 10 people without the usual pandemic precautions in place as long as all of those family members, friends or neighbours make a pact to socialize only with each other, while in Alberta, the cap for your "cohort" is your household plus up to 15 other people.In B.C., the guidelines for a "bubble" are now to try and limit it to six people. Officials initially said the members of your immediate household can be "carefully expanded" to include outsiders, with the goal of limiting the number as much as possible — since these are people you're allowed to kiss, hug, chat with and dine with, all without masks or distancing.WATCH | B.C. moves toward limiting bubbles to 6 people:It's a concept being adopted in several countries around the world. And while it works well in principle, experts warn it may be harder to maintain at this point in the pandemic.Bubble makes sense in 'theory'"As a theory, the bubble makes a lot of sense," said Dr. Dominik Mertz, an associate professor in the division of infectious diseases at Hamilton's McMaster University. "But there's a lot of confusion from people over what it is."He also added it can be tough to do safely, particularly if the bubble involves multiple households "who all have different risks."Say you have two four-person households socializing without the usual pandemic precautions. On paper, it follows the current Ontario guidelines.But what if one person is back at work, leaving them exposed to dozens of colleagues? Or either family's children are in school, where physical distancing and mask wearing might be a challenge?A small sphere of contacts can quickly expand to include everyone that each family member comes in contact with, which means the bubbling approach really isn't "useful" anymore, according to Tuite, an assistant professor at the University of Toronto's Dalla Lana School of Public Health.'It's not going to work for all people'Raywat Deonandan, an epidemiologist and associate professor at the University of Ottawa, agreed it's not a "perfect model" at this point in the pandemic."It would've worked better back when things were fully locked down," he said, adding there's still merit in bubbling with a few close friends or family if everyone is cautious."I don't want to remove any tools from the table," he said. "If bubbling is working for some people, keep on doing it. But it's not going to work for all people."For instance, a supply teacher, with a social network of students and staff in various classrooms or even buildings, can't realistically have a social bubble without any precautions, Deonandan said, while someone working from home might be able to do it more safely.WATCH | 'Exponential' growth in new cases in parts of Canada, says infectious disease specialist:For many people, losing their bubble could mean a long, lonely winter, made worse by mental health struggles or living alone."We know there are benefits to having that human contact," said Dr. Nitin Mohan, a physician epidemiologist and assistant professor at Western University in London, Ont. But when dropping temperatures push people indoors, where transmission risk is higher, and families start making plans to gather over the upcoming stretch of holidays, it could make adhering to the bubble principles even tougher. Bubble burst? Isolate for a while Mertz says Canadians should already be planning for upcoming gatherings like Thanksgiving.If outside-the-bubble family members want to celebrate together, find ways to do it safely, he says, by meeting outdoors and staying apart as much as possible. Otherwise, you're blending several household bubbles together and upping the risk for everyone.And if you do throw caution to the wind for a turkey feast, there's another approach: Isolate yourself as much as possible for two weeks after the gathering. "That would give us downtime, so in case someone got infected, you are not spreading it from that gathering into each individual bubble," Mertz said.The various experts who spoke with CBC News acknowledged the challenges in sticking to even the safest bubbling plan, with peer pressure, slip-ups, and our innate desire for human connection all potential obstacles.For that reason, Dr. Andrew Morris, an infectious disease specialist with the Sinai Health System and University Health Network in Toronto, stresses the onus shouldn't just be on individuals to reduce transmission.From a system-wide perspective, he says, provincial governments need to ensure every piece of the pandemic plan is adequately resourced: testing capacity, contact tracing, personal protective equipment and hospital staff."If you can't test people who are symptomatic, then you can't contact trace ... and you can't identify people who are about to become symptomatic and are unknowingly and unwittingly spreading the disease," he said.Ontario gathering sizes reducedOntario officials say they're working to increase testing capacity amid hours-long lineups in multiple cities, including Ottawa and Toronto.The province is also lowering the maximum size limit for private gatherings — things like backyard barbecues or dinner parties, with precautions in place among people in different social circles — in some regions.The new limits will be 10 people indoors and 25 people outdoors, with hefty fines of $10,000 or more for organizers who flout the rules.Deonandan calls that the "single best policy intervention" for controlling the spread of COVID-19, given the growing body of research showing large gatherings can be hot spots for virus transmission."Mask wearing, that's important. Distancing, that's important, too," he said. "But time and time again we see explosions of cases in otherwise controlled areas ... driven by these super-spreading events."Even smaller gatherings can fuel the virus's spread, like infections after a family outing documented in Toronto, and a 10-person cottage trip — which would still meet the province's new rules — that led to 40 new cases in Ottawa.It's not clear if anyone involved in those gatherings was bubbling together, and Mertz stresses in all situations, the same safety precautions apply."Whether you continue with the bubble concept or not, it comes down to the less people gathering, the more time you can spend outside, the more you can spread out — the lower the risk."