Quick summary: Many claim it is safe to end the lockdowns because COVID-19 has run its course through our populations. Unfortunately, this is not true, and we must still contend with this public health emergency in sensible ways to limit its spread.

In the last month or more,  there have been many claims made in social media and elsewhere that we have reached herd immunity for COVID-19 and it is, therefore, safe to end the shutdowns that have been implemented to reduce the pandemic’s spread. Herd immunity limits the spread of a communicable disease because the majority of the population is immune to it (which results in a measure of protection for those who are not immune). 

Last week, the Lancet published Have deaths from COVID-19 in Europe plateaued due to herd immunity? The authors, Okell et al, reviewed data from the European Centre for Disease Prevention and Control as of May 18, 2020, as well as some studies on the prevalence of SARS-CoV-2 antibodies in some European countries. They examined death rates rather than rates of positive testing since tests were not universally available for those suspected of being infected. (The authors note that even death rates are not without controversy). 

The first finding they report is that COVID-related deaths have different peaks by country: 

  • Germany: 95 deaths per million population
  • Netherlands: 332 deaths per million population
  • Italy: 525 deaths per million population

Considering these countries have roughly similar demographics, population density, health care, etc., the variance in peak death rates suggests that Germany and the Netherlands were able to implement a barrier to thespread of the disease.

Second, they note that death rates are lower in countries that implemented shutdowns and physical distancing earlier than those countries who suffered higher death rates. Okell et al note that if herd immunity had already been achieved, the lockdowns would not have reduced the number of people dying.

Third, the study found that for each country, a higher death rate correlated with more positive tests for COVID-19 antibodies. The authors suggest there was less spread of the disease in countries with fewer deaths. If herd immunity had been reached, each country would have similar rates of positive COVID-19 antibodies.

In line with previous antibody studies and herd immunity predictions based on R₀ (reproduction number), the authors conclude there is no evidence for herd immunity in Europe. They acknowledge that there are other health and economic costs to shutdowns, but advise against complacency since the spread of the virus has not peaked in Europe.

There is every reason to believe that this study’s findings are applicable to North America and elsewhere. Europe has been one of the hardest areas hit by this public health emergency, so if this region has not achieved herd immunity, it is unlikely to exist elsewhere. Furthermore, there is ample evidence of other locations in North America and around the world where cases and hospitalizations have soared since restrictions were eased.

This graph is from the appendix of Have deaths from COVID-19 in Europe plateaued due to herd immunity? in the Lancet.

ACTION YOU CAN TAKE:

In an upcoming post, we will explore options for more targeted restrictions that might allow more social and economic activity. In the meantime, we must remember that this public health emergency is not over and we must not be complacent. Continue physical distancing, hand hygiene, and mask-wearing as best you are able.

And of course, please share this post with your networks so your friends, family, and colleagues can know they need to remain cautious about potential exposure to the SARS-CoV-2 virus.

BLOG POST AUTHOR

Cindy Beernink, ND, M.Ed. (June 2020) lives and works in Toronto, ON. She is a founding member of the Naturopathic Alliance.