A Newcastle-based viral immunologist has advised that more familiar viruses and bugs that cause the common cold and other illnesses will return with uncertain consequences.
During the COVID-19 pandemic, social distancing, isolation and face masks have meant community transmission of other respiratory viruses and bacteria has been happening much less often.
As the COVID-19 vaccines are rolled out, restrictions are expected to ease and people will spend more time together.
Associate Professor Nathan Bartlett, of HMRI and the University of Newcastle, said the population may have "extra vulnerability or susceptibility to these other viruses because that level of baseline community protection may be reduced".
This means less immunity to pre-existing viruses because they haven't been circulating.
"There's already some evidence of a rise in RSV [respiratory syncytial virus] - the virus that puts babies in hospital with bronchiolitis," he said.
"Rhinoviruses and other [non-COVID] coronaviruses that cause the common cold may return stronger."
Children will spread these viruses at school and increase community transmission, which "we know triggers asthma attacks".
While it was unknown how the pre-existing viruses would act, there could be "unforeseen consequences of a year of isolation and social distancing and a lack of normal exposure to a whole lot of other infections".
Dr Bartlett said it was worth reflecting on "what social distancing has taught us about the impact of respiratory viruses in general on community health".
"We're not seeing people dying of influenza or as many asthma attacks. When we resume normal life, we'll be looking at these things differently now they're in our conscious awareness.
"Hopefully we'll be thinking about approaches that better protect all of us, particularly the most vulnerable, from respiratory infections.
"If we didn't fully acknowledge that before, we must acknowledge it now."
Nevertheless, he said life must return to some form of normality.
"We've got to take the plunge back into society at some point. But the rules of the game have changed and the consequences of that are uncertain."
During the pandemic, influenza rates have fallen dramatically.
"The flu vaccines we have should be fine because there's been no pressure on the virus to mutate, as it hasn't been circulating. Flu vaccination remains vital to protecting the community," he said.
"The current advice is not to have the COVID vaccine and influenza vaccine on the same day. The recommended interval between a flu jab and a dose of COVID vaccine is 14 days.
"Maintaining protection against seasonal flu whilst establishing protection against COVID-19 is the goal. But we must also keep a close eye on other viruses such as rhinovirus and RSV, as we slowly but surely return to normal life."