After a year of social distancing and following public health measures to curb the spread of Covid-19, scientists and psychologists say we should be able to go back to pre-pandemic social norms such as hugging or shaking hands.

However, this is contingent on levels of vaccination and our ability to feel comfortable with each other and living with germs and microbes.

At the start of the pandemic, coronavirus researchers advised constant surface sanitation for fear of viral transmission, but now surface transmission is scientifically seen as low risk.

In some cases, however, we continue to attempt to zap germs, bugs and microbes with sprays and disinfectants to make our own homes, work places and public spaces safer and less likely to create a Covid-19 threat.

Covid-19 has meant we are willing to do everything to stave off catching a serious virus. But some experts warn those actions could be threatening us and the microbes that protect us.

Pre-pandemic there were warnings about superbugs and over consumption of antibiotics having an impact on our health and the global health system.

Now scientists fear increased disinfecting and zapping is impacting on our microbiome - the trillions of bacteria that live on and inside us.

Hyped-up hygiene is potentially weakening these important microbes and potentially putting our immune systems and ability to fight infections at risk.

"That community of bacteria, fungi and viruses is an ecosystem that lives on and within us but we feed it and we benefit from it," Professor Liam Fanning, UCC Professor of ImmunoVirology, told RTÉ's News at One.

Our bodies house a vast ecosystem of organisms, and Prof Fanning says the pandemic may have had an adverse effect.

"While on some level they might threaten us, on other levels we depend on them to provide us with certain types of nutrients to digest certain types of food and in some instances to provide a defence mechanism by educating our immune systems against some more pathogenic bacteria," he said.

"If we start zapping everything around us - which we have with Covid - we are actually taking away plenty of these beneficial microbes."

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In January, a global group of health researchers published a paper in the Proceedings of the National Academy of Sciences (PNAS) raising the alarm about the microbial fall out that may follow in the pandemic’s wake.

First, there is concern that we are killing microbes that help us.

Second, we are not collecting enough microbes from others, as we have stayed apart during the pandemic. Microbes from other places and people help our microbial systems build defences against potential threats and infections.

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Dr Brett Finlay, first author of the PNAS study, and a Professor of Microbiology at the University of British Columbia in Vancouver, told the News at One that we need to protect our microbes and we face increasing levels of asthma and obesity post-pandemic with the biggest impact on the young and elderly.

"History has shown that when we deprive ourselves of these microbes then bad things happen. We are worried that we are depriving ourselves these microbes due to Covid and this is having consequences downstream," said Dr Finlay.

"We are really going to see this in the early kids and the elderly because that is when the microbes have the biggest effect. An early baby really needs microbial exposure to develop their brain normally, their gut normally, their immune system normally. And, as you get older - post 65 - your microbes fall off a cliff.

"A lot of studies show that if you can be exposed to younger peoples' microbes it actually helps prevent microbes going bad on you which hastens the ageing process," Dr Finlay added.

"We predict that we are probably going to see an increase in asthma and obesity - especially in the next three to five years post-Covid," said Dr Finlay.

However, although scientists argue we need to expose ourselves to more microbes, and not live in a bubble, it is difficult to ignore that staying apart during the pandemic combined with mask wearing and social distancing led to a decline in colds and flus.

"The flu season this year was practically non-existent and it is questionable whether we will have much of a flu season coming because people have probably accepted the wearing of masks and the prevention of transmission of infections. We have a much more educated population. I think for some people masks and that kind of protection will be here to stay," said Prof Fanning.

Getting back to pre-pandemic social norms of hugging, shaking hands or crowding in to a room is important to how we operate as a species, Dr Finlay argues.

"From how we function as a species, we really do need to get back to sharing microbes extensively because we know that is very beneficial.

"How do we behave? I find myself backing away from complete strangers when I previously wouldn’t have done that. We are so trained to be paranoid of each other now and this is not good for microbial transmission," he said.

As social tactile creatures, can we get our heads around resuming normality and living with germs again? Dr Trudy Meehan, a senior clinical psychologist at the RCSI Centre for Positive Psychology and Health, told the News at One normality will happen again.

"All of our drives push us to be social and we are social creatures but there will probably be different pathways for different people.

"We are going to have to go through a period of adjustment where some people are going to run out in to the world and be really happy to get back there. Others people are going to have more heightened anxiety and more fears.

"We are going to have to tolerate quite a bit of difference for a while until things settle down," said Dr Meehan.