Natural Herd Immunity Strategies will not save us from COVID-19
As Canadians continue to hunker down in the country-wide lockdown, Quebec’s Premier François Legault expressed interest in herd immunity this week as a means to reopen businesses and allow children to return to school. Similar calls have been made by many as a means to loosen the lockdown restrictions by achieving what is called herd immunity.
Herd immunity is a form of indirect protection from viruses where a majority of the population has been infected and recovered from a virus, thus becoming immune. Once herd immunity is achieved, it is much harder for the virus to spread, and will spread much slower, although it is not eliminated completely.
The UK initially tried this strategy, but had to change course very early on as is it became clear that hospitals would be overwhelmed very quickly and many avoidable deaths would occur. Sweden is currently using this strategy, even as its death-per-million ratio is almost 10 times higher than some of their nordic neighbours. If Canada had the same death rate as Sweden currently, we would have over 8000 Covid-19 deaths, rather than our current 2465.
This is a mistake.
Consider our home Canada, with a population of about 37.6 million. In order reach herd immunity we would need to reach about a 60% infection rate (though admittedly, the science isn’t clear here) meaning about 22.5 million would have needed to be infected and survived. Given that the estimated time for a safe and reliable vaccine to be produced is about 2 years, we we will likely not be able to reach reach herd immunity before a vaccine without overloading our healthcare system. This would lead to a massive spike in completely avoidable deaths.
Thousands of scientific studies are currently underway on different treatment methods for Covid-19. These treatment methods are either antivirals or are based on techniques to inhibit the devastating effects of the infection. These studies will be reported in the coming weeks and months and there are possibilities that we will be able to reduce mortality long before we have a vaccine. This is perhaps the most important reason for trying to push the problem ahead as far as possible. To do everything to flatten the curve. By pushing back as many serious cases into the future as possible until a treatment is approved, we will save thousands of lives.
Another major factor mentioned by Bonnie Henry, BC’s Provincial Health Officer leading the charge against the pandemic, is that we can not 100% isolate and identify the vulnerable. While we know that the elderly and those with compromised immune systems, there are many cases of individuals who are high risk that were not aware. We do not know exactly who is vulnerable, as even young people can require serious care with people under 40 accounted for 12% of all hospitalizations.
As Henry also mentioned, in many cases it is just not possible to completely isolate many elderly people. Care homes, grocery stores, and even apartment buildings are all places where the elderly live and come into contact with other carriers of Covid-19.
There is still much to be learned about the current virus, which has spread to over 210 countries. According the World Health Organization, it is still not known whether antibodies will protect against a second infection. Antibodies are Y-shaped proteins used by the immune system to neutralize pathogens such as bacteria and viruses. The amount of time these antibodies can protect and individual is still unknown, as there is currently no evidence that people who have recovered from COVID-19 and have antibodies are completely protected from a second infection.
One final thing to consider is that we don’t know the evolution of the virus. Theresa Tam, Canada’s Chief Public Health Officer, questions that although Covid-19 doesn’t seem to evolve and mutate as quickly as other viruses, what will it look like a year from now? There is just too much at stake. As a member of the Federal Government, it is her duty to err on the side of caution.
Despite all the unknowns, Tam is encouraged that researchers from countries all around the world are collaborating and sharing findings. We all should be too. Treatments and vaccines are our only escape out of this mess.