Jun 15 2020

COVID-19 Lockdown and the Flu

There is pretty clear evidence now that the lockdown worked in “flattening the curve” and reducing cases, hospitalizations, and deaths from COVID-19.  By one estimate the lockdown has already prevented about 60 million cases in the US alone, and about 250,000 additional deaths, perhaps more. This doesn’t even take into consideration what would have happened if the pandemic was allowed to overwhelm hospital systems around the country. In the Northeast, which was hit early and hard, hospital systems were overwhelmed in that they had to reconfigure their resources, and compromise on protocols in order to meet the demand. In some NY hospitals they had two patients on one ventilator. Imagine this, but far worse, and more widespread. How many deaths not directly related to COVID-19 would have resulted from this strain on the system?

So I think we can take fair comfort in the fact that the lockdown, as painful as it is, has at least worked as intended. Many people have raised the question – did the lockdown work also on the flu? If so, why don’t we do some version of the lockdown during the height of flu season? We now have data on the effect of the lockdown on this year’s flu season in the northern hemisphere – it stopped the flu season about 5 weeks earlier than is typical.  It’s possible some of this decrease in numbers is due to fewer people seeking treatment, but it’s likely that it is mostly due to reduced spreading of the flu virus.

This year in the US the flu season was toward the higher end in terms of cases and deaths – not out of the range of typical flu seasons, but at the bad end of the spectrum. In the US there were between 39 and 56 million cases of flu this year, with 24-62 thousand deaths. The upper limit of flu season deaths is around 65 thousand. The reason for the wide estimate range is because most people don’t get tested in order to confirm that their flu-like illness is indeed the flu. So confirmed cases are a small percentage of total cases, which are estimated by clinical presentation. Globally the estimated number of flu deaths each year is 290,000–650,000.  Right now the global number of deaths attributed to COVID-19 is 436,000, but the number of new cases is still on the upswing.

Before you fall prey to the “COVID-19 is just a bad flu season” fallacy, keep in mind that the pandemic is not over yet. And, as stated, this is with lockdown. But, what does this say about how we handle typical flu seasons, and how we will likely handle COVID-19 in the future? Here are some thoughts.

First, we won’t really know what the full impact of this pandemic is until it is largely over. There are many potential downstream effects – effects on other illnesses, on medical care, and on the economy – that will all need to be taken into consideration. Looking at total excess deaths during the pandemic, and in the aftermath, will be very helpful. Current estimates are that there are more excess deaths than the official count of COVID-19 deaths. In the US, for example, there may be as many as 30,000 excess deaths so far not attributed to COVID-19. These might be uncounted COVID-19 deaths, or deaths from other causes. It is also interesting to consider that the excess COVID-19 deaths may be even greater, because the total numbers are somewhat offset by reduced flu deaths, and deaths from crime, auto accidents, and homicide.

In any case – does this new information about the lockdown also reducing the flu have any implications for lockdown policy going forward? I think it does, and I think this pandemic will have a longstanding effect on public behavior. When the 2003 SARS pandemic hit China, for example, the government recommended everyone where face masks to reduce spread. Since then mask wearing in public has become common behavior among Chinese citizens. We may see a similar effect around the world.

With regard to the flu season, I don’t think we will engage in economic shutdown in order to flatten the flu curve each year. This is because the flu season comes every year, and we can’t lockdown every year in any way similar to the COVID-19 pandemic. But what we can do is get much better at avoiding spreading the flu by wearing masks in public during the height of the flu season, staying home, social distancing, and getting tested if you have symptoms, washing hands and surfaces thoroughly and not touching your face with unwashed hands. Better flu hygiene could significantly reduce the severity of flu seasons. And, of course, we need much higher compliance rates with the flu vaccine. The effectiveness of the vaccine changes from year to year, but it is always advantageous to get vaccinated. There is a lot we can do to reduce spread of the flu without reducing economic activity.

What this tells us is that we have become complacent about the flu. It’s not news because it happens every year – but every year we have hundreds of thousands of deaths world-wide, and tens of thousands of deaths in the US, from the flu. We should not be complacent. Perhaps the current pandemic is teaching people the skills to avoid spreading illness. Everyone has their personal face mask, and it is more acceptable to wear them in public. I do wonder what the next flu season will be like.

Further, it remains to be seen what will happen with COVID-19. The pandemic will eventually burn itself out, but we may have a second or even third wave first. However, SARS-CoV-2 may also simply become endemic, which means there may be regular periodic waves of COVID-19 indefinitely. It may become like the flu (although its seasonality is not yet demonstrated). That means we need a strategy for dealing with COVID-19 whenever it pops back up. We will need to get really good at reducing the spread of the virus, without shutting down the economy. The lockdown is a card we cannot play often. We used it as an emergency to reduce a pandemic that took us by surprise. It may be decades before we can really weather another such lockdown.

What about a COVID-19 vaccine? This will clearly help, but it is at least 6 months away, and maybe longer. We also don’t know how well it will work, and how long immunity will last. But a vaccine will help, and hopefully the seriousness of this pandemic will motivate people to get it, and further marginalize the conspiracy mongering and extremely dangerous anti-vaccine movement. Effective anti-viral treatments will also help, but viruses are notoriously difficult to treat. We have lived with the flu for decades, and anti-flu drugs are only modestly effective.

It seems clear that this pandemic will change our behavior. The lockdown worked, but it was painful, and it is not a strategy we can employ often or without significant cost. Therefore we need to get really good at reducing the spread of contagious diseases by changing our behavior. We can no longer be complacent. To some extent we will become a mask-wearing, social distancing, hand washing culture. This is now part of living in a globally connected world with over 7 billion people and growing.


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