Double jeopardy

For the first time in over a century, humanity has been forced to face up to its own insignificance. There have been other diseases, of course, but nothing since the great flu of 1918 has distorted regular life quite as much as Covid-19. From its uncertain beginnings in Wuhan, China, in the dying days of December 2019, the virus has hopped from host to host and city to city to infect practically every nation on earth. With over 25 million cases so far, and more than a million deaths, only isolated microstates in the Pacific have survived unscathed.

However, if nearly every place has suffered, they have not suffered equally, and not just because of government mismanagement here or an efficient lockdown there. Rather, the planet has faced Covid-19 seasonally, with countries in the southern hemisphere battling their first wave through the long autumn months of March and April, right as their influenza season was starting and the northern hemisphere’s was tailing off. Given what we know about how such diseases work, with cases rising in cold weather, that sounded ominous – and no one was surprised when cities like Buenos Aires and São Paulo started to struggle.

Moreover, early data from the UK suggests that between January and April the risk of death was 2.27 times higher in people infected with both viruses than those struck with SARS-CoV-2 alone. A study at Wuhan’s Tongji hospital also noted that coinfection was a significant risk factor for prolonged hospital stays and linked it to patients shedding SARS-CoV-2 for an average of 17 days, five more than those without influenza.

And yet the experience of our cousins south of the equator in the intervening months may actually offer some hope. Though coronavirus is harder to suppress, social distancing and a careful vaccination campaign seems to have dampened the annual flu season in many of these places. Of course, that doesn’t mean the same will happen in London, New York and other northern centres, but the experiences of countries in Latin America and Oceania are worth considering. By combining common sense hygiene with vaccinations and a robust diagnostics regime that can distinguish between the two illnesses, there’s plenty their northern cousins can do.

Going south

If you’ve followed the news over the past few months, you’ll likely have seen praise heaped on a small island nation most people will never visit. And why not? Since Covid-19 reached its shores at the end of February, New Zealand has endured less than 2,000 cases and, at the time of writing, just 25 deaths, winning prime minister Jacinda Ardern plaudits for her decisive lockdown and containment policies. But if victory against coronavirus has justifiably taken up the most attention, Dr Sarah Jefferies explains that her adopted country has also seen success against a far older foe: influenza. “The level of influenza, and the limited illness we’ve seen from that, is very [low],” says Jefferies, a Scot by birth but now a public health physician at the Institute of Environmental Science and Research in Wellington.

She has a point. According to one local expert, for instance, flu rates in New Zealand this year were almost 40 times lower than they were in 2019. Nor are the Kiwis alone in having a quiet time. Across the Pacific, Dr Claudia Cortes describes how her native Chile has seen a “surprising drop” in viruses other than Covid-19. “Over the past few weeks, our numbers for influenza have been almost zero,” says Cortes, an infectious disease specialist at Santiago’s University of Chile and vice-president of the Chilean Society of Infectious Diseases. Beyond Chile, meanwhile, southern hemisphere countries from Argentina to Uruguay to South Africa have all had the same experiences, their flu rates collapsing even as coronavirus numbers spiralled.

How, then, to explain this surprising decline? One reason, both Jefferies and Cortes agree, is lockdown. With their countries already hiding from coronavirus, it was harder for influenza to spread too. Another, says Jefferies, was her country’s travel ban. Over recent years, New Zealand’s influenza season has been starting earlier – possibly courtesy of infected arrivals from the northern hemisphere. But with most foreigners banned, and returning nationals expected to quarantine, the dangers of previous flu seasons have tumbled. It probably helps that practically every country on earth has unveiled some kind of public health crusade. Though they’re meant to tackle Covid-19, all those warnings about hand-washing and masks help keep flu at bay too.

Yet, more than all that, perhaps the most interesting facet of the southern experience can be summarised in a single word: vaccination. A fully trialled vaccine for coronavirus is still months away, but that hasn’t stopped many southern countries from expanding their flu vaccination campaigns. Nor is it very surprising. For elderly patients, or those with pre-existing conditions, Covid-19 is nasty enough already. Add regular influenza to the mix and you risk sparking an even deadlier cocktail. So New Zealand began its flu-busting war earlier than normal, and secured an extra 360,000 doses, specifically for healthy people aged three to 64.

Too much corona

For all the problems his country is facing, from violent unrest to government incompetence to well over 200,000 coronavirus deaths, Dr Robert Lahita sounds remarkably chipper. A surprise, maybe, to those who follow the republic’s course on the evening news. But as Lahita, a professor of medicine at Rutgers University, explains, there is at least one reason to be cheerful. “There’s a point of care test being developed for coronavirus, and it’s in the field now being tested. That’ll make the diagnosis of Covid-19 much faster and much easier – it’ll be done on the spot.” Even better, this is bolstered by other FDA-approved tests, which allow doctors to test patients for coronavirus and influenza together.

Once you appreciate the significance of these developments, Lahita’s enthusiasm is easier to understand. After all, if the Trump administration is incapable of arranging a robust lockdown or a concerted vaccination campaign, testing can still be a fundamental cornerstone of northern hemisphere countries’ strategies as the nights lengthen and winter approaches. Think of it like this – though coronavirus is far more virulent, its aches and pains and fever mean it shares many symptoms with influenza. Now imagine someone goes to their doctor with just these complaints – and then admits they spent the night before at a bar with 50 other people, hardly impossible in lockdown-shy (and bourbon-friendly) states like Texas or Kentucky. As Lahita puts it, that “debauchery” could mean that a new coronavirus outbreak has just started – but these new tests can prove it.

More to the point, figuring out whether someone has coronavirus or influenza has huge healthcare implications. For starters, it helps inform individual treatment plans, as patients suffering from flu are likely to experience severe symptoms far sooner than those whose immune systems are being attacked by SARS-CoV-2. Lahita notes that, unlike coronavirus, flu can also be beaten “fairly easily” with drugs like Tamiflu. On the other side, as available Covid-19 treatments are likely to be in short supply for some time yet, and the way they might interact with influenza is largely unstudied, the decision to use them needs to be informed by the best possible diagnostic information.

The ability to differentiate the two viruses also informs broader policies. If officials know that their hypothetical patient definitely doesn’t have Covid- 19, there’s no need to waste time and resources contract tracing all their buddies from the bar, or impose lockdown measures on the whole town. Nor is the US alone in developing these sorts of tests. Back in the Old World, for example, the NHS unveiled rapid tests based on technology that could potentially be used to test for both infections simultaneously, with the health secretary claiming it’ll be “hugely beneficial” as winter arrives.

Of course, an even better solution would be to simply vaccinate citizens for the current strains of influenza, helping doctors treat Covid-19 more efficiently. That’s especially true given northern countries have already suffered through one total lockdown, making a second even harder to manage. “If I were John Q Public,” says Lahita, “I’d really want to be vaccinated to assure myself that I’m not getting the flu. And then if I got something, I’d run to the hospital and be tested for Covid-19.” Having already lived through this reality over the past few months, Jefferies makes a similar point, suggesting that widespread flu vaccination was “essential” in New Zealand’s battle against coronavirus, if nothing else because it helped prevent the health service from being overwhelmed with false admissions.

I’ll be back?

Of course, it’s one thing for quiet, enlightened New Zealand to roll out a near-universal flu vaccine campaign. It’s quite another to repeat the trick in the sprawling, dysfunctional US, especially with the White House’s current tenant. Nor do past statistics necessarily offer much hope. Though numbers have increased somewhat in recent years, only 45% of US adults got the flu vaccine in 2019, with figures for some European countries arguably even worse. Just 47% of vulnerable older Finns got the flu jab in 2018, for example – a figure only narrowly bested in Sweden, France and Italy.

Perhaps the solution, then, is to vaccinate as many people as possible – then support everyone else with robust diagnostics, helping doctors and officials figure out what illness patients have as quickly as possible. As such, countries on both sides of the Atlantic are stockpiling flu jabs, with the NHS, for instance, expanding its campaign to everyone over 50 (although, as with almost everything related to the pandemic, some are beginning to face shortages). And whatever happens with vaccines and testing, the shocks of the past year will probably have some effect too. As Cortes puts it, even “very simple measures” can make a big difference, from wearing a mask to washing your hands after you go to the bathroom. However desperate things might feel, in other words, perhaps our fate isn’t quite out of our hands just yet.

2.27x

Greater risk of death in people infected with both SARSCoV- 2 and influenza between January and April, compared with those infected with SARS-CoV-2 alone.
British Medical Journal

360,000

Extra flu vaccine doses obtained by the New Zealand government, specifically for healthy people aged three to 64.
Ministry of Health NZ

Combined Covid-influenza tests

At the time of writing, the FDA has issued four emergency use authorisations for tests that detect and differentiate the viruses that cause Covid-19 and flu – to Biofire Diagnostics, Qiagen, the Centres for Disease Control and Prevention (CDC), and, most recently, Roche.

All four test a single patient sample for multiple respiratory diseases, requiring fewer swabs, reagents and personal protective equipment, which have already been in short supply amid the pandemic and could be even harder to access over the coming months. The Biofire and Qiagen tests, which were released in the spring, require nasopharyngeal swabs, while the CDC and Roche technologies also work with nasal (both) and throat (CDC only) samples. Whichever way a swab might be taken for one of these tests, the fact it doesn’t have to be repeated helps to limit patient discomfort.

As the newest entrant to the market, Roche believes that its test, which runs on the company’s cobas 6800 and 8800 systems and is also available in countries accepting the CE mark, offers the highest throughput and quickest time to results. Numerous other companies are working on point-of-care and even at-home combination tests, though so far only lab tests are available for use.