Tuesday, August 4, 2020

We're thinking about Covid-19 the wrong way. It's not a 'wave' – it's a wildfire

Like a fire, the virus relentlessly seeks out its fuel, humans, and will keep spreading as long as it has access to that.

‘We hope vaccine development efforts will prove effective, but hope is not a strategy.’ Photograph: David Swanson/EPA

By Michael T Osterholm and Mark Olshaker

We have no previous experience with a worldwide coronavirus pandemic, so when Sars-CoV-2, the virus that causes Covid-19, began spreading, public health experts leaned on our experiences with influenza pandemics to inform their predictions. These pandemics are often described in terms of “waves” and “troughs”. We have now seen enough to replace the ocean analogy with a better one: wildfire.

Like a wildfire, the virus relentlessly seeks out fuel (human hosts), devastating some areas while sparing others. It will continue spreading until we achieve sufficient herd immunity – when 50 to 70% of the population has developed protective antibodies – to significantly slow transmission. We will achieve herd immunity either through widespread infection or an effective and widely available vaccine. No amount of official happy talk will change that course.

We now have compelling evidence that Sars-CoV-2 is not affected by seasonality or regional weather; it spreads by the human contact and mixing that occurs in areas of high population density. We don’t yet know whether immunity is permanent or short-lived. We also don’t know if a vaccine, if and when we develop one, will be a bull’s-eye success like the vaccines for polio or measles, or more of a hope-for-the-best agent like seasonal flu vaccine. We hope vaccine development efforts will prove effective, but hope is not a strategy. Like HIV, Sars-Cov-2 is here to stay, and realism must inform our strategic response.  Read more >>