New Year arrived with a bang, an explosion of coronavirus across Canada and the U.S.
COVID-19 Data Explorer – Our World in Data
People reporting on TV, from politicians to public health scientists, seemed to be alarmed and a bit surprised. They shouldn’t be. Shortly after South Africa reported the new variant Omicron at the end of November, they provided statistics that showed that the number of cases was doubling every 2-3 days. This is really simple math. You don’t need a sophisticated epidemiological model, you don’t even need a calculator to see the impact of this over a few weeks. If 4 people with Omicron arrived in Canada from South Africa before the variant was identified, those 4 cases could have spread to 32,000 people by January 1, 2022, which is roughly what the latest case count is for Canada.
There were early reports from South Africa that Omicron is less severe than Delta. But the population profile in South Africa is a lot younger than the UK, Canada and the U.S. It was not so clear that this pattern of milder infections would be true for older people who have been a lot more vulnerable to the previous strains of the coronavirus.
On Dec 22, a careful study was published by Neil Ferguson and his team at the Imperial College London. He is one of the pre-eminent epidemiologists in the world. The analysis controlled for many variables such as age and sex and concluded that the reduction in the risk of hospitalisation for Omicron relative to Delta was 40-45%. This now seems to be an accepted characteristic of Omicron.
https://www.imperial.ac.uk/mrc-global-infectious-disease-analysis/covid-19/report-50-severity-omicron/
But even if the probability of hospitalization is lower, when there are so many more cases than Delta, there may be an overall increase in hospitalizations. In fact, patient admissions to hospitals have now started to increase sharply.
COVID-19 Data Explorer – Our World in Data
This is what is alarming many public health officials. This trend could overrun the health care system. So, many regions are re-introducing social controls. While most governments are insisting that “lockdowns” are a thing of the past, in fact what we are seeing now is “creeping lockdowns”.
One thing that does not seem to be reported very clearly is how long this wave will last. In South Africa it seems that it peaked quite quickly and is coming down (see first graph) but that does not mean it will happen here.
To try and answer this question, I updated my coronavirus model for the Omicron variant with the following assumptions:
1. By January 9, Omicron will account for 90% of the coronavirus cases in Canada.
2. Omicron is 4 times as transmissible as Delta.
Based on this, it does look like the Omicron wave will peak more quickly and decline more quickly than the earlier waves. The peak is towards the end of January with cases returning to pre-Omicron levels at the end of February. What determines when the decline begins is when the total immunity based on both vaccinations and natural immunity from people who have had Covid reaches a critical threshold. This model is very sensitive to the assumptions, so the peak cases may be more or less than 100,000 depending on how effective the various new restrictions are in reducing social interactions and transmission of the virus.
One thing that some epidemiologists are saying is that almost everyone will get Omicron, even vaccinated people. I don’t see anything like this. The total number of people in Canada who had Covid-19 at the end of the Omicron wave in the model, both symptomatic and asymptomatic, is about 8 million people out of a total population of 37 million. So about 30 million people will not get Covid because they are being protected by the vaccine, in spite of many breakthrough cases. So it does not make sense from a health perspective to surrender, throw caution to the wind and not worry about getting infected because “everyone will get it anyway”. It’s hard to predict if you will have a mild case or not. In addition, very little is known at this point what the effect of Omicron is on “long covid”. With earlier variants, 5% of people who were infected have lingering symptoms for many months and in some cases much longer.
What is my risk of getting Long Covid
The other thing some epidemiologists are saying is that this may be the last wave of the pandemic after which Covid will become endemic. It won’t disappear and will continue to infect people, but not at an epidemic rate, and will become more like a seasonal flu. However Dr. Fauci commented that most pandemics in the past have subsided after two waves, but Covid-19 has been unprecedented and has now proceeded to a fourth wave. So the most experienced experts in the field are really not able to predict what will happen. And the threat of another variant after Omicron is of course still possible.
