Epidemics of infectious diseases can be unpredictable but they often come in waves. History has left hard lessons showing that a virus can quickly return – and with deadlier force.
Just over a century ago, the three-wave Spanish flu pandemic that claimed at least 50 million lives, killed more people in the more virulent second wave in the autumn of 1918 than in the first that spring, including in Ireland.
Public health responses during that pandemic were complicated by the fact that the world was at war. Regional inaction and the increased movement of people as the war drew to a close deepened the severity and death toll in 1918 and 1919.
Now, as Ireland reopens from a severe lockdown imposed to flatten the curve of infection and death, the risk of coronavirus infection rates rising again remains high with the increased interaction and movement of people. The risk is particularly high given that a vaccine to eradicate Covid-19 is some time, possibly years, away and seroprevalence studies which measure past rates of infection show little “herd immunity”, leaving large swathes of populations still susceptible to the virus.
The two-month steady descent from Ireland’s peak of deaths and infection in mid-April has allowed the country to move into the second phase of lockdown relaxations and accelerated the Government’s plan to reopen society and the economy. This will, inevitably, put more people in closer contact with each other and raise the possibility of new infections increasing again.
In the early stages of the pandemic, public health specialists were able to predict how infections would soar in an unmitigated scenario, where, based on the reproductive rate of a highly transmissible disease, one Covid-19 case would infect four or five others.
Now, even the experts admit they cannot predict how the virus will spread if it returns.
"I honestly don't have a crystal ball on this one. I don't know what we're going to learn about this virus over the next six months," Prof Philip Nolan, chair of the modelling advisory group on Covid-19, told the Oireachtas special committee on the pandemic response on Tuesday.
Opinion is divided on how an increase in infections could come or indeed whether it is even likely. The State's chief medical officer Dr Tony Holohan has said that a second wave is "not inevitable". He said he hoped the reopening could proceed "without seeing a change in the level of disease that causes us either to have to pause or go back on some of the [lockdown] measures we have used".
Others have a different view.
"This virus will almost definitely come back again. It is not a case of 'if' it is almost guaranteed that it will be a case of 'when'," says Prof Sam McConkey, infectious diseases specialist at the Royal College of Surgeons in Ireland.
Given the prevalence of the disease in countries such as the United States, Rusia and Brazil, McConkey believes the virus will be circulating in the world for the foreseeable future, possibly for between five and 10 years, and that the State has to become better at keeping coronavirus out and, if it is discovered again in the community, identifying it quickly and managing its suppression again.
“If we do a really good job, it might be a second ripple rather than a second wave and there might be a second and third and fourth ripple. We might deal with it better. If we do a really bad job, it will be a second tsunami and then we have learned nothing,” says McConkey.
1 Tracing and testing
The view of most public health and medical specialists is that the second wave will be different.
The past three months of lockdown have been so traumatic for people and caused such an upheaval in their lives that the response the next time around, should the virus return, has to be less severe and managed differently.
"Inevitably, as restrictions lift, there is a full expectation that there will be a second wave," said Dr Mary Favier, Cork-based GP and president of the Irish College of General Practitioners.
“There are two issues: one is when it will happen and the other is how big it will be. With a little bit of luck it will be just a wave, not a surge, and that it will be entirely manageable.”
Among the advantages heading into any potential second wave is that there is now a greater understanding of the virus, how it spreads and presents itself clinically in sick patients.
In March the State struggled to test people for Covid-19; it has since built a capacity to test up to 15,000 people a day for the disease, turning around tests from swab to result in 1.2 days on average, and taking three days to trace contacts of the newly infected.
"We will be able to identify cases and hopefully then we will be able to isolate them, contact trace and treat them. That should help prevent us having a significant surge in cases," says Dr Catherine Motherway, an intensive care specialist working in Limerick.
Some believe the rapid Covid-19 alert and surveillance system may need to go further.
McConkey says the State may need to extend checks to second- and third-degree contact tracing, similar to how Facebook generates contact suggestions for friends of friends and friends of friends of friends. He uses the example of his wife potentially getting infected and people he works with being her second-degree contracts and having to self-isolate.
“The aim there is to try to control the resurgences of the disease really thoroughly and in a way that prevents it spreading into the general population again, through more extreme isolation and control of the people in the immediate vicinity of others who have it, but then at the same time have more relaxation on the general population,” he says.
Few expect a return to full lockdown or “phase zero” should the virus return, not because of the likely public anger to such a response, but because there may be strong evidence that the risk of transmission of the virus is lower in creches and primary schools, for example.
“We used a big sledgehammer when we locked people into their homes,” says Motherway.
“It would be very hard to lock people down totally again but hopefully over the next few weeks we will learn which bits of those public health measures did the most to reduce the curve and which bits can be applied without interfering with our economic life as much as we have,” she says.
From his position on the modelling advisory group, Nolan said this week that “the management of the second wave will be different” and that there could be “more targeted measures introduced to control the future outbreaks before the sort of blanket measures that we have seen”. Contingency plans will be needed, he said.
In Asia, large second waves were averted by such targeted, quick actions. Nationwide lockdowns being replaced by ones on regions or sectors and the partial reimposition of restrictions.
"The lesson for Ireland here is that we must remain vigilant for new cases," said David Higgins, an analyst with consultancy firm Carraighill which tracks and compares new Covid-19 cases against first-wave peaks. "We cannot rule out some restrictions being imposed again."
2 Being vigilant about indoors and alcohol
Two issues identified as posing the greatest danger for a return of the virus are indoor crowds and alcohol. The State’s chief medical officer has warned about house parties – events that can combine the two.
“Alcohol is a distance inhibitor because it doesn’t take more than one or two drinks for us all to say, ‘Ah sure I’ll be grand, I’m only here for 10 minutes’,” says Favier.
“By three or four drinks, everybody is everybody’s best friend and everybody’s sharing a corner of the bar along with bottles, glasses, food and cutlery,” say the doctor. “That is the biggest one we have to negotiate: the impact of alcohol on our social inhibitions and our ability to self-monitor.”
In South Korea, a cluster of new infections was discovered in early May after weeks of almost no fresh cases and traced to Seoul's nightclub district as social distancing was relaxed. Some 90,000 people were traced for contacts and almost 300 infections were linked to the clubs. The infection of more than 100 people was linked to a single person attending three clubs over one weekend.
3 Being sensible about individual behaviour
Personal responsibility and individual action – from adhering to physical distancing and respiratory etiquette to early awareness of symptoms and contacting a GP quickly – is seen as essential to building an early-warning system that could help avoid a second wave.
“All of us with sniffles, coughs or fevers should be getting our Covid-19 tests,” says McConkey. “Then if it does start to spread in Ireland again, we will see it at a very early stage, rather than waiting until there are thousands of cases.”
The low prevalence of the disease makes individual, preemptive action essential.
The reopening of society means public health officials can no longer rely on the few simple rules that applied during the lockdown for the multitude of risk scenarios facing the public.
"We have to rely on people's individual decision-making and good sense in order to reduce the risk," says Pete Lunn, head of behavioural research at the Economic and Social Research Institute.
“People need to be alert to and understand situations that are more risky than others and act to reduce the risk of transmitting the disease.”
4 Preparing the hospitals
The risk of a second wave of the Covid-19 pandemic coinciding with an outbreak of other infectious diseases, such as seasonal flu or measles, raises the potential for a “double wave”.
Doctors want the prepandemic “baseline” of 250 intensive care beds across the State’s hospitals doubled permanently and more isolation units to segregate Covid and non-Covid cases over the winter.
"You can't do that in one season but they need to start making significant plans," says Motherway, whose term as president of the Intensive Care Society ended last week.
Unlike during the first wave, when hospitals suspended non-Covid care to create capacity to cope with the pandemic, the acute care system must have plans to tackle a second wave of Covid-19 along with managing surgeries and accidents that were not happening in the first wave.
“We only got one shot at the first wave where we could just suspend everything. You can’t do that a second time. It is just not going to be tenable,” says Favier.
“The big challenge now with any surge is that we now have to run non-Covid work in parallel with Covid and our hospitals will really, really feel that strain. I would have more concern about that than we did in the first place with how many ventilators we had.”
She says there is now no situation that carries zero risk from Covid-19 and hospitals “need to find workarounds and doing the new normal” and to move beyond “this paralysed, rabbit-in-the-headlights of Covid” that is preventing the return of some regular healthcare.
5 Preparing the nursing home sector
The sector worst hit by the pandemic is the one facing the biggest challenge from a second wave. Many nursing home staff were forced out of work having contracted Covid-19, leaving care facilities struggling to cope with a virus that killed many elderly residents.
McConkey believes care homes will need at least 20 per cent extra staff for “surge capacity” for a second wave. This will inevitably result in some privately-run homes not being economically viable and the larger nursing home groups being able to staff-up more quickly and to cope better.
“Nursing homes have been chronically under-staffed for several years. They are going to have to start cherishing their staff as the most important thing they have,” says McConkey.
Given the risks to nursing homes from Covid-19, staying prepared generally, not just for a second wave, is essential to beating the virus, with increased focus on stringent restrictions on visitors, social distancing, hand hygiene and the wearing of personal protective equipment.
Regular, mass testing of care homes – or even batch testing of all nursing home staff and residents before testing individuals to identify the positive cases – is considered critical to being able to isolate Covid-19 cases and protect the most vulnerable group to the coronavirus disease.
Appetite for risk
Predicting how or when a second wave might emerge is even more unclear than preparing for the first wave because it comes down to the risks members of the public are willing to take.
“Some people will take more risk, some less. That is the nature of humans. They differ in how much risk they could take whereas before we just knew we had to get the number of cases down,” says behavioural economist Pete Lunn.
“The world has become more complex and then you are also in a far more complex set of rules for governing the behaviour so it has become much more messy and hard to predict.”
