The Case Against Levelling-Up
Tags: Covid 19, Lockdown, Ireland

Updated: 7/10/2020 to adjust the time for confirmed cases to be hospitalised from 7 days to 14 days and from confirmed cases to fatalities from 14 days to 28 days.

Over the last couple of days there has been a flurry of reporting and speculation about Ireland’s current COVID status and what it will mean for our lockdown level, not to mention the prospect of a leap to Level 5. The airwaves lit up with argumnets for and against this, but often without the supporting evidence. In what follows I will attempt to summarise the three main arguments that I have heard, and the relevant supporting data.

As I wrote this it was announced that the country would not be moving to Level 5, and instead all counties would move from Level 2 to Level 3. Will this work?

Today’s cases are not comparable to April’s cases.

Today’s case numbers are not the same as case numbers from April because we weren’t testing then and so there was much more unconfirmed infection back then than there is today.

Today’s 7-day rolling average of confirmed cases is just under 50% of the corresponding peak back in April but, the argument goes, our current infection numbers are probably a lot less than their corresponding peak back in April, because we have so much more testing today. If this is true, then we should be comparing infections today to infections in April. I’m going to argue that this is not in fact true, and that cases today can be compared to peak cases from April, at least as a way to judge where we are in this second wave.

In a previous post I described how to estimate true infection numbers from a combination of confirmed cases, test positivity rates, and fatalities. In short, there are a number of models with which to do this, and by taking an average of their estimates we get the graph below; the thick grey line shows the daily confirmed cases and the thick red line shows the corresponding estimate of daily infections based on this average (each model’s individual estimate is shown as a thin grey line). Note that the y-axis uses a now-familiar log scale; it’s not ideal but it makes it easier to evaluate the summer lows and spring highs on the same graph.

As expected, daily infections are much higher than daily confirmed cases. The difference was much greater in March and early April because of lower testing capacity and high test-positivity rates, but it narrowed after May, as testing improved and positivity rates fell. Unfortunately the scale of this difference is masked by the log-scale of the y-axis, but notice how 100 daily cases in March corresponded to about 5,000 daily infections, a huge 50x differential. Compare this to when we again hit 100 cases per day in August, and when there were only about 450 infections, a 4.5x differential.

The important point is that the ratio of cases today to peak cases in April (49%) is very similar to the ratio of true infections today to peak true infections in April (51%). Thus, even when we control for testing, confirmed cases today do provide a representative picture of where we are in this second wave in relation to April’s peaks and therefore, it is not correct to assume that today’s case numbers fail to offer a like-for-like comparison to April’s numbers.

Transmission is growing more slowly now.

Cases are growing much more slowly now compared with April, which means we are not facing the explosion of cases we saw in April.

When cases were growing in March and April we saw doubling-times (the time it takes for cases/infections to double) of about 5–6 days. This meant that when we were at 50% of peak levels back in April we were only 5–6 days away from the actual peak. This is shown in the graph below. The growth trajectories of early and more recent cases/infections are shown as the dashed lines, annotated with their corresponding doubling-times over the period.

In recent days our doubling-times have been much longer, 16–18 days, which means cases/infections are growing more slowly than they were in April. However, there is surely no room for complacency, because if we continue as we are, then we can expect to hit peak levels from April before Halloween. There is little comfort in a 16–18 day doubling-rate. It just means that cases are growing a little more slowly than they were back in April, but they are still growing, and this will still produce an explosion of cases if it is allowed to continue.

The slightly positive news is that these longer doubling-times do provide some limited time to change our behaviour and turn things around, but time is running out and we will need to act quickly and decisively if we are to take advantage of the time we have. In the early days there was a lot of regret that we did not act more quickly because of the difference that even a few days can make in an exponential growth regime. Well, the same is true today, and if we don’t do something now we may look back at this time as a missed oportunity.

Infections are currently much less severe.

Infections are much less severe and it is less likely that hospitals will be over-run or that the fatality rates of April will return.

A potential bright-spot can be found in the severity of cases during recent months, compared to the early months of the pandemic. For example, during the first 100 days of the pandemic Ireland accumulated just over 25,000 confirmed cases and, assuming it took an average of 14 days for these cases to be admitted to hospital, they led to almost 3,200 hospitalisations, for a hospitalisation rate of just over 12% (or 0.126) . The same calculation, based on the most recent 100 days of hospitalisations, indicates a much lower hospitalisation rate of just under 4% (0.038).

In a similar way, and as shown in the graph below, we can calculate the case fatality rate during the first 100 days and the most recent 100 days, this time allowing for a 28-day period from case confirmation to death. During the early part of the pandemic the case fatality rate was just under 7%, but it is just 1% now.

While we might take some comfort from these these lower hospitalisation and fatality rates, they are unlikey to reflect a change in the severity of the virus; we are dealing with the same virus today as we confronted in April and it remains just as deadly.

So why the reductions in hospitalisations and fatalities? It is likely that they are due to a combination of factors: the identification of many more mild case this time around due to better testing and earlier detection, lower infection doses due to social distancing and mask wearing, the continued effective shielding of at-risk groups, and, perhaps, some improvements in treatments. But if the virus breaks through to at-risk groups — and there is evidence that infection rates are increasing among the over 60s — then presumably these rates will rise. As I write this the reporting is that it was just such a projected increase in hospitalisations that led to the NPHET Level 5 recommendation.

Another thing to remember is that we cannot afford to allow COVID to dominate our hospitals as it did in March and April. Our healthcare service must continue to operate so the idea that we still have “room” for COVID in our hospitals and ICUs is a non-starter.

Levelling-Up?

Where does this leave us in relation to the need to level-up? The data speak to a second wave in Ireland that is growing, albeit more slowly than the first wave, and with fewer severe infections, so far. The argument for levelling-up is that the severe cases will follow. But a return to Level 5 would have a devastating long-term impact on the economy, and it would not be without its own public health consequences, such as the spill-over effects on mental health, the unwillingness for people to avail of non-COVID health services etc. But clearly something does have to change.

The good news is that the combination of slower growth and reduced disease severity, for now, probably means we have brief window within which to turn this around, but only a couple of weeks, and only if we get it right from the start. In this light the decision to move to Level 3 nationwide is probably worth a shot, as a final opportunity to do this. If it works it will be because we have all changed our behaviours to work together and it will show us that we can control the virus without locking down fully. If it doesn’t it will be because we have not all changed our behaviours, and we will be confronted with a very divisive Level 5 as Christmas approaches.

Encouraging Collective Action

Getting it right in Level 3 means recreating the sense of collective action that we had during the first lockdown. To do this we need: (a) a simple message about what we should do differently; and (b) there needs to be a clear sense of solidarity, a sense that we are all in this together, playing our part, making sacrifices for the greater good.

One of the most compelling recent messages has been “reduce social contacts by 50%” because it is simple and effective — reducing our close contacts by 50% will reduce transmission opporunities or the R-number of the virus by a similar degree — and yet even this becomes somewhat muddied by the 5-level system. For example, in Level 3 we are told to limit household visits to no more than 6 people from a single family. Presumably this means “at a time” or “per day” or is it “per week”? That detail is not clear and it must surely mean that there are some families with a few as 1 or 2 visitors per week, while others remain compliant with dozens of different visitors per week (as an extreme, we could get to 42 visitors per week based on 6 per day for 7 days, for example). And while commonsense tells us that less is more, more is apparently permitted under the regulations.

I think too that we are missing an important opportunity to provide feedback to people about how they are doing. Every week my phone gives me a summary of my weekly screentime, as a way to help me to monitor my online habits. I would like my COVID tracker app to provide me with a similar report about my weekly close-contacts. I don't need to know who they are, but I would like to know how many there are, and how this has changed over time. It might be useful to know if certain days or locations are associated with more contacts than others. I might be able to do something to reign in these busy days. At the very least it would keep this important aspect of my COVID behaviour top of mind. Do I have similar close contacts to others in my age group or location? How are national close-contacts changing week on week?

Summarising important behaviours in this way may help to foster a greater sense of solidarity. It might be just what we need during a time when social media and the mainstream media seem to revel in highlighting the all too frequent transgressions of others — the house parties and mask-less gatherings, the GAA fans who refused to follow the post-match guidance, or the deplorable VIP golf outings— which only serve to erode any sense of solidarity that we might have. Of course these transgressions need to stop. They simply can’t be tolerated because they are putting peoples’ lives and livelihoods at risk.

Level 3, Done Right

So we are now in Level 3, which realistically is probably the minimal viable change if we want to further control the current growth of the virus, but will it be sufficient? I’ve heard some experts predict that this will only serve to delay the inevitable, that while Level 3 might slow growth it won’t reverse it, and it will lead us, eventually, to the next level. That is a very real concern. At least we now have a chance to find out for ourselves but let’s face it, moving to Level 3 can only be effective if we can rely on every one to do what is needed. If we can then I think we do have a shot at turning this around.

This virus can’t be bullied — just ask Trump — and it can’t be ignored, but if we respect it, then we can learn to live with it. The original advice that we should all behave as if we have the virus remains good today, because most people who are infected don’t know they are infected and many might never know. If we all follow this advice, all of the time, then we will be safe and our loved ones will be safe; the economy will remain open and our jobs will be safe; our schools will remain open and kids will get the education they need and deserve. That sounds much more appealing to me than a stay-at-home order in Lockdown Level 5, so let’s make the most of Level 3 and get it right.