This week in pandemic news, there is more chatter about vaccine candidates. The good news is that there are a number in the works, which increases the likelihood that at least one will make it through all the hurdles. However, even at the height of a pandemic, there is an inconvenient statistical hurdle that may come to the fore. In order to know whether a vaccine works, you need to recruit a large cohort of test subjects, some of whom will get the vaccine and the others won’t.
Then you must wait for subjects to either get COVID-19 or not, which means testing the subjects periodically. Even if the vaccine works, subjects in the control group may contract COVID-19 and be asymptomatic, and, conversely, subjects who have been vaccinated may have antibodies to COVID-19; but still contract a case. Then, RT-PCR testing will be needed to see if they have active virus.
In the U.S., we are in phase where the chances of someone contracting the virus on any day is small (≈ 1 in 10,000), which means that even if you recruit 10,000 subjects, you will have to wait 100 days for 1% of them to be exposed and either contract COVID-19 or not, as the case may be. After digesting that, how do you feel about a vaccine being ready this year based on trials in the U.S.? You could accelerate this by adhering to the Josef Mengele School of Medical Ethics and forcibly inoculating the subjects with COVID-19, this approach is generally frowned on; but society may be willing to adjust its moral trade-offs, e.g. is it ethically permissible to allow a subject to voluntarily be exposed to a serious pathogen? How do you know if a willing subject really does understand the risks and therefore is providing “informed consent”? Or we could outsource the trialing of vaccines to places in the earlier stages of their pandemic cycle so that the rate of natural exposure is high enough to answer the question of whether a vaccine candidate provides protection (and how much)? That, too, has ethical problems because the places where the pandemic will be raging are likely to be under-resourced to begin with and the monitoring of a vaccine trial will be a burden on the existing healthcare system (such as it is). Potentially, this would open up the rich world to the criticism that it is outsourcing its dirty work to the poor of the world.
Yesterday was Memorial Day when we remember those who gave their lives in defense of freedom and is often referred to as Poppy Day, with the custom of wearing a red poppy. In the days before industrialized agriculture and herbicides, fields hosted many more plants than commercial cereals and potatoes. Springtime fields in Europe were a blaze of poppies. As World War I raged, the poppies still managed to put on a show in the craters and churned countryside, as captured by Lt. Col. John McCrae’s “In Flanders Fields”:
In Flanders fields the poppies grow
Between the crosses, row on row,
That mark our place; and in the sky
The larks, still bravely singing, fly
Scarce heard amid the guns below.
We are the Dead. Short days ago
We lived, felt dawn, saw sunset glow,
Loved and were loved, and now we lie
In Flanders fields.
Take up our quarrel with the foe:
To you from failing hands we throw
The torch; be yours to hold it high.
If ye break faith with us who die
We shall not sleep, though poppies grow
In Flanders fields.