It came from nowhere, ripped savagely through our lives and is currently overstaying its welcome. But when will the Covid-19 pandemic end? Or will it even end?
The second answer is easier to answer than the first. There will be an end to this pandemic, as there has been to others. But how soon that arrives, and in what manner, remains opaque for now.
Even the great influenza outbreak of 1918-19, which ravaged the world over two years and three waves, drew to a close after more than 50 million deaths and as immunity was conferred on those who recovered.
Flu lived on as an endemic, seasonal, but less serious infectious disease, occasionally mutating into deadly forms that again gave rise to pandemics. It still kills over 600,000 mostly vulnerable people a year worldwide.
We know from past experience that eradication of SARS-CoV-2 is an unlikely outcome; the list of diseases that have ceased to exist is a short one. It includes the cattle disease rinderpest, mentioned in Ulysses but eradicated since with the help of an effective vaccine, and smallpox, which was last diagnosed in 1977.
Four other human coronaviruses are endemic in the population, meaning they circulate continually without giving rise to large surges. Mostly they cause only mild cold-like symptoms
"Pandemics come and they go. In the past herd immunity would come into play in a resolution. You'd often end up with a low level of infection, with limited outbreaks," according to Prof Paul Moynagh, an immunologist from Maynooth University.
The chances of eradicating Covid-19 are “very slim”, he says, based on our previous experience of coronaviruses.
Smallpox eradication worked because of a good vaccine, the lack of an animal reservoir for the disease and the fact that it was easy to identify people with symptoms. With Covid-19 none of these criteria was filled until the development of the first vaccine late last year.
Almost 20 years ago another coronavirus, severe acute respiratory syndrome (Sars), caused an epidemic that was stopped only by isolating the sick, quarantining their contacts and implementing restrictions. Sars victims showed symptoms long before becoming infected, making the task easier.
Yet four other human coronaviruses are endemic in the population, meaning they circulate continually without giving rise to large surges. Mostly they cause only mild cold-like symptoms.
Prof Moynagh believes this more benign outcome, where SARS-CoV-2 becomes endemic, is the more likely one in our current crisis.
“It will stay with us, and there will be outbreaks, especially in winter, but even with variants, vaccines and rising immunity will protect most of us from getting very sick.”
Infectious diseases expert Prof Sam McConkey is no stranger to dire predictions in this pandemic. Last March he forecast more than 100,000 deaths if no action was taken to control the virus. While this figure has been kept to 4,000 so far, this was on the back of successive lockdowns and near continuous restrictions.
What will happen from now on, he believes, depends on the actions of government.
We'll have more of the same for a long time to come, maybe slightly better because vaccines will improve the death toll
In a best-case scenario he sees a large majority of people getting vaccinated quickly even as lockdown is kept in place. With even schools kept shut, he believes we could reach a “zero-Covid” state in “two or three months”, which would allow a modest domestic reopening of society.
While further opening up with other countries could be possible if they were to successfully follow a similar tack, he does not foresee us travelling abroad until 2022. And there would be local lockdowns again, sparked by outbreaks.
What he thinks is the most likely scenario is that Ireland will "muddle through" Level 3 to 5 on the Government's Covid plan, with the levels of restrictions oscillating in accordance with outbreaks and surges of the virus.
Vaccines alone will not be adequate to bring the pandemic to an end, he maintains; none is completely effective, and there will be people who decline to get them. “So we’ll have more of the same for a long time to come, maybe slightly better because vaccines will improve the death toll.”
If that doesn’t sound bad enough, Prof McConkey has a worst-case scenario involving the spread of variants of the virus that can evade the vaccine response. Our most powerful tool to fight the pandemic would stop working and we would be back to Level 5 lockdown long-term, with yet more serious cases and deaths.
The vaccines that have been developed can be reformulated to provide protection against new variants, he acknowledges, but this would take time.
Getting more people vaccinated gets harder after the most vulnerable and those most enthusiastic about vaccines have been inoculated.
Prof Moynagh points out that up to 20 per cent of the population may already have been infected with Covid-19, and should therefore benefit from a measure of immunity. He believes the benefits of vaccination will be felt very quickly based on the experience of Israel and the UK.
Once large numbers are vaccinated, society will face the question of how many Covid-19 deaths and serious illnesses it is prepared to tolerate, he says.
Flu kills hundreds of people most winters (until this one just past) yet we do not lock down society to prevent this.
In the UK Prof Devi Sridhar, chair of global public health at the University of Edinburgh and a prominent commentator on the pandemic, predicts a return to a “somewhat normal domestic life” within the next six or eight months, while international travel would continue to be restricted. This is because of the risk that some new variants could evade both vaccines and our natural immune responses.
The emergence of more infectious variants, such as has already happened, may also require that a higher percentage of people be immune to reach herd immunity.
Yet getting more people vaccinated gets harder after the most vulnerable and those most enthusiastic about vaccines have been inoculated. It will, for example, prove a lot harder to get from 70 per cent to 80 per cent cover than from 60 per cent to 70 per cent.
Other imponderables include supply difficulties for vaccines, and shorter than anticipated duration of vaccine-conferred immunity.
No eradication
In January, Nature magazine surveyed more than 100 immunologists, virologists and infectious disease experts on whether Covid-19 could be eradicated. Almost 90 per cent said it would become endemic, but only 40 per cent felt it could be successfully eliminated from some regions.
Clearly consensus is lacking about the way forward. The story of the pandemic has taken many twists over the past year, and is likely to take more before it is over. Despite the development of vaccines in super-quick time, the speed at which new, problematic variants has emerged has surprised many and induced caution in governments everywhere.
As Dr Mike Ryan, the WHO's head of emergencies, has warned, Ireland and other countries could be "in serious trouble" if new variants of Covid-19 "change the rules of the game" in terms of preventing transmission.
This pandemic has been very severe – it has affected every corner of this planet. But this is not necessarily the big one
The mass rollout of vaccines across the world – and not just in the wealthier, developed nations – will help enormously, but will take time.
“SARS-CoV-2 can probably never be globally eradicated, because of its presence in many animals (including cats and dogs) and because of incomplete vaccine coverage and variable degrees of immunological protection,” according to a recent opinion piece in The Lancet, co-authored by Dr Peter Piot, who helped discover the Ebola virus and led the global fight against Aids.
“Hence, ongoing strategies to deal with the endemic presence of SARS-CoV-2 in populations over the long term will be needed.”
Covid-19 is a societal challenge as much as a medical one, Prof Moynagh points out.
The pandemic has induced changes in our behaviour that were unimaginable over a year ago, from the wearing of masks to the avoidance of close contact with others. Much of this behaviour is likely to continue beyond its end-point. In that sense all of us are marked whether or not we picked up the infection.
Dr Ryan says the likely outcome is for Covid-19 to become another endemic virus that will remain a very low-level threat, in the context of an effective global vaccination programme.
“Humans are social beings. We will go back to the old normal, eventually; we should be aiming to do that,” says Prof Moynagh.
Yet Dr Ryan has also warned of the threat posed by the next pandemic.
“This pandemic has been very severe – it has affected every corner of this planet. But this is not necessarily the big one.”
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