I knew a pandemic was coming, but I didn’t think it would be so soon. In the weeks before the outbreak of Covid-19 began in Wuhan, I was putting the finishing touches to a book about the psychology of pandemics. In my work as a clinical psychologist, I had spent years studying past outbreaks and examining what they could teach us about the psychological effects of the next virus.

Based on the hallmarks of previous pandemics, some of my predictions about coronavirus have proved eerily correct. I imagined that we’d see growing anxiety, racism, panic-buying, the proliferation of conspiracy theories, and sporadic instances of looting and theft – but also altruism and generosity, as people reached out to the physically isolated with offers of help.

As a result of Covid-19, some will become fastidious germophobes, striving to avoid touching ‘contaminated' surfaces

Previous outbreaks, such as the 2009 influenza pandemic and the 2003 Sars epidemic, suggest that a public health emergency can have lasting effects on the psychology of a population. In the case of Covid-19, some of these effects are obvious: many people will lose their jobs and endure financial hardship; others will suffer the devastation of losing loved ones; marriages and relationships will collapse under the pressure of lockdown.

In an ongoing research project with fellow psychologist Gordon Asmundson, we evaluated reported levels of fear and anxiety among almost 7,000 adults from Canada and the US. While 75% of respondents seem to be coping well, 25% have developed what we’ve called Covid stress syndrome. These people have intense fears about becoming infected; they worry about the social and economic impact of Covid-19; they have coronavirus nightmares and persistently check the internet for news related to Covid-19, which may further heighten their anxieties. These people also tend to be xenophobic – they are wary of foreigners, who they fear may be carriers of the virus.

Anxiety about your own mortality, fears stoked by a deluge of online articles: these are the most obvious psychological effects of coronavirus. Others may be less obvious at first. Based on studies of disasters such as floods, hurricanes and earthquakes, an estimated 10% of people affected by traumatic events go on to develop severe psychological problems such as mood disorders, anxiety disorders or post-traumatic stress disorder (PTSD). These symptoms typically arise soon after the disaster. Such findings suggest that 10% of people affected by coronavirus – possibly more – will develop psychological disorders during or after this pandemic.

However, if coronavirus is anything like Sars, this percentage could be substantially higher among those infected with the virus. A number of people who had been hospitalised with Sars in 2003 later developed PTSD. A four-year follow-up study of 70 Sars survivors found that 44% of people developed the disorder. Even after recovering from Sars, 82% of these people had PTSD years later. PTSD symptoms tended to be more severe in people who had a high mortality risk, low social support, and close relatives who suffered or died from Sars.

It’s likely that even those who aren’t infected with coronavirus could also develop psychological symptoms. Isolation and confinement, even if only for a few weeks, can cause lasting anxiety. People quarantined for prolonged periods in cramped accommodation, sharing a bedroom with multiple occupants, or trapped at home in an abusive or coercive relationship, may be especially vulnerable to developing PTSD symptoms during and after the outbreak.

Other psychological effects will have more to do with environmental and social changes. Covid-19 has forced societies to trial entirely new ways of living. School lessons have moved online; work meetings take place over Zoom; groceries are delivered via Amazon. We’re living through the first global pandemic in the digital age, where the internet has made it possible to withdraw from the outside world.

Even before the outbreak, people were already working from home, shopping online, and having food delivered, rather than going to restaurants. The outbreak may have further entrenched the direction in which society was already heading. After coronavirus has passed, we may find that life never fully returns to “normal”. Risk-averse, digitally connected people could continue retreating to the safety of home.

As a result of Covid-19, some people will become fastidious germophobes, striving to avoid touching “contaminated” surfaces or shaking hands. Germ phobias, which are typically symptoms of obsessive-compulsive disorders, arise from a combination of genetic and environmental factors that interact with one another. In other words, when a person with a particular genetic makeup has a traumatic experience with infections (such as developing a severe case of Covid-19), they are likely to develop a germ phobia. Such phobias are typically chronic, although milder phobias may be short-lived.

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Still, there is some cause for optimism. The many people who volunteered to help others during the pandemic will experience renewed purpose and meaning in their lives. And those who adjusted better to self-isolation – that is, people who are open to new experiences, optimistic and emotionally stable – are more likely to fare well during and after the pandemic. Not everyone possesses these characteristics, but people can improve their resilience by learning new coping strategies, through practices like cognitive behavioural therapy (a valuable resource for this is the BounceBack programme, which is freely available online).

The future implications of coronavirus are still uncertain. But based on what we know from previous outbreaks, we can predict that this pandemic will have profound psychological effects on the people living through it.

• Steven Taylor is a professor and clinical psychologist in the department of psychiatry, University of British Columbia, and the author of The Psychology of Pandemics