A Very COVID Christmas
Tags: Covid-19, Data Science, Ireland

Granted the prevalence values we are using have been smoothed — remember they are based on the 7-day rolling averages of cases rather than actual daily cases — but still it’s remarkable just how similar the two waves are, especially during the 3-week period when their restrictions were roughly aligned: from approximately 7 days before each peak, to 18 days after each peak, the relative prevalence in wave 1 and 2 is almost identical. We can see too how the decline in prevalence in wave 2 began to slow, from November 15th, compared with the corresponding decline in wave 1.

This degree of similarity suggests that we were able to control the virus just as effectively during most of Level 5 as we were during the spring lockdown. This is encouraging because the spring lockdown was more strict (e.g. schools weren’t open, travel was even more limited, and even more people were working from home) plus improving weather meant it was easier to limit indoor exposure during wave 1. Despite this, Level 5 has proven to be just as effective, for an extended period of time.

Implications for the Christmas Period

As we prepare to move from Level 5 to Level 3, prevalence is approximately 100 cases per 100k of population. What does this mean for the coming weeks and for Christmas itself?

The last time we were at this prevalence level, outside of Level 5, was on October 7th, which was the day we entered Level 3 nationwide. So, the current move to Level 3 is consistent with that, but it also underscores the importance of viewing the transition to Level 3 as less of a lifting of restrictions and more of a restoration of the restrictions that were previously required to curtail transmission.

Level 5 has helped to protect us over the past few weeks, because closures limited the opportunities for transmission, but it would be a mistake to view the easing to Level 3 as a sign that it is safe to be less cautious. On the contrary, the drop from Level 5 to Level 3 only increases the likelihood of transmission, because re-openings create additional high-risk settings. Therefore we will all need to be even more careful and more cautious about how we conduct ourselves, even if our natural instincts suggest it is safe to relax.

It is also worth remembering that when a similar re-opening took place during the summer, prevalence was only between 3 and 12 cases per 100k, rather than the 100 cases per 100k we have now. Relaxing restrictions at this higher baseline level means there is a correspondingly higher risk of transmission now. Concretely, it means that there is now an 8x–33x increase in the risk of coming into contact with an infected individual, compared with the summer, all other things being equal. And, of course, all other things are not equal: it’s colder now and we are moving indoors; it’s Christmas so there will be more (and larger) parties and gatherings; and ’tis the season to be jolly, which means hugging, and kissing, and transmission, oh my!

Conclusions

We should be pleased that Ireland has done so well in wave 2. We might disagree about how we achieved this success – lockdowns are far from ideal and other countries are proof-positive that alternative approaches do exist – but lives have been saved, and serious illness has been avoided. And because of this success we are able to ease restrictions sufficiently to facilitate a somewhat normal Christmas. This is an option that is not available to many countries where the virus continues to spiral out of control. However, we will only look back on this as the right thing to do if we respond in a way that is responsible and safe.

December has the potential to be a perfect storm for this virus: lifting restrictions will significantly increase the risk of transmission, our natural Christmas behaviours will amplify this risk, and prevalence is high enough for this to translate into an explosion of infections. The price of these reduced restrictions has to be a significant increase in caution, because nobody wants COVID for Christmas!

If we do exercise more caution, then we can avoid this perfect storm, and we may look back on December as a positive turning point in how we deal with this virus. If we succeed, then we might even be able to keep prevalence low enough to avoid additional restrictions in the New Year. This is perhaps our last chance to demonstrate that we can operate a more open economy and control the virus. We know this is possible because other countries have shown it can be done with a fraction of the restrictions we have had to apply. Let’s do it!