We’re all familiar with ‘flattening the curve,’ the idea that shutting down large aspects of society and creating social distancing will slow the spread of the disease – the net effect is to not overwhelm the medical system. We saw what happened in Italy – their healthcare system overwhelmed, ventilator shortages, and people dying while awaiting care. In the US, we certainly have flattened the curve. There has been a sufficient number of ventilators and ICU beds. These results were due to our efforts – Americans who took precautions to heart. Yet, doesn’t this serve only to postpone the inevitable? Isn’t everyone going to get the virus sooner or later? After all, this is a novel virus and one for which none of us are likely to have preexisting immunity. We are ripe for infection, and the rate of speed absent social distancing is brisk.
Of course, the more people get it, the more people become immune and the harder it is for the virus to continue to spread. The equation to calculate the percentage of the population that needs to be immune to confer broad herd immunity is pretty straightforward: it’s 1 – 1/R0. If each person with the disease infects three others, then once two out of three people are immune, the disease doesn’t have enough targets to keep spreading. For COVID, we probably have to have 70% of the population immune before the virus dies out.
We are nowhere close to that. New York City – the US epicenter of the disease, has an estimated 25% population immunity. That suggests that we are early in the game. But if 70% of the population is going to eventually seroconvert to positive, then a utilitarian argument may be that we should flatten the curve just enough to avoid overwhelming the healthcare system, but no more. This would allow us to get through this as fast as possible without leading to excess deaths. After all, as long as everyone who needs care is not denied due to overcrowding, it’s a victory. On its face, the argument sounds good! On the other hand, if we deconstruct this argument from a practical, epidemiologic and ethical perspectives, a different reality appears.
From a practical viewpoint – if we delay the spread of disease, it not only aids the hospitals cope with census, it buys time for us to do medical research, gain clinical experience in treating the virus, and find vaccines. I can say for certain that I am better able to manage ICU patients today compared to two months ago. I know better how to micro-manage their care – which is often the difference in survival. I’ve learned the best position for a patient to be in, what bacterial pneumonias are likely to superimpose themselves, about the risk of thrombosis. These are practical. Knowledge has improved how we care for these patients. As a result, more patients are surviving. The bottom line is that you’re better off getting sick from coronavirus today then you were in March.
Second is the epidemiologic. It turns out that outbreaks don’t just stop when you reach herd immunity. They have inertia. You can overshoot predicted herd immunity. That’s just because of the dynamics when you have such high transmission or attack rates.
Finally, the ethical considerations. Even if the total death rate is the same (which it is not), compressing those deaths into a shorter period of time still robs people of life. The reality is that 100% of people die eventually. As physicians, the war against death is one we always lose. But we fight to push that day as far into the future as possible. Watching people who are struggling for a breath makes me aware of how valuable a breath actually is.
Our friend in this battle is the vaccine. There are more than 160 potential vaccines and experts tell us that we may have a viable vaccine by the end of the year. This may or may not be overly optimistic. Funding has be plentiful and different approaches are under study. Small and large companies are collaborating. Plans for mass production are under way. The U.S. said it would fund and conduct the phase III trials — the final step to determine how well the vaccine works and if it’s safe — of three candidates: Moderna Inc., AstraZeneca, and Johnson & Johnson. The Moderna and AstraZeneca vaccines are already being tested in people.