Medical decisions are often binary, while evidence comes in shades of gray. The way we choose to frame questions can guide us or lead us astray. Consider two examples:
Hugging after vaccination and vaccines for pregnant women
One month ago, I argued one side of a debate regarding restrictions after vaccination. I noted that several lines of evidence suggest the risk of transmission after vaccination is incredibly low, and it is reasonably safe for vaccinated people to relax some restriction, such as hugging a loved one, or having a dinner party for vaccinated guests. Just this week, Anthony Fauci endorsed my position, supporting such gatherings, and saying that after his daughter is vaccinated, he will be .
A persistent objection to my view (and now Dr. Fauci's) is that we do not know that vaccinated people cannot have asymptomatic infection and spread SARS-CoV-2. In fact, even though mounting data suggests that the chance of this occurring is, at best, very low, it is true that we do not know it to be 0%. In fact, I speculate that it is not 0%, and only a matter of time before we document the phenomenon. That doesn't change my position -- life will never be zero risk, but it is an admission of what we don't know.
Now consider another vaccine question. Should a pregnant woman be advised to get the vaccine? Of course, I support all people making the choice that's right for them, but strictly speaking: the clinical trials that led to emergency use authorization of the vaccine did not include pregnant women, and the truth is: we do not know.
Pfizer agrees, and is to determine if pregnant women can safely be administered the vaccine. While we await the results, the headlines are correct, "." In fact, the World Health Organization recognizes this, and initially advised against vaccination of pregnant women, , despite the fact that there was no substantive new information.
From an objective vantage, there is more data that vaccination will reduce the spread of the virus than information regarding maternal and fetal outcomes from the vaccine, and yet, the popular framing has it backwards. The same person who objects that we don't know if vaccines halt transmission will proudly proclaim that vaccination is safe in pregnancy. They may even tweet a picture of a pregnant woman receiving it.
I personally believe that vaccination likely will be shown to be safe in pregnancy, but I cannot help but note the double standard. When do we want certainty, and when are we willing to tolerate risk?
Shifting beliefs
Our views on this topic have evolved even during my 15 years in biomedicine. We used to be reluctant to treat pregnant women without well-controlled evidence that a strategy was safe. For instance, both the SSRI class of medications and seizure medications have faced longstanding reluctance among providers to give during pregnancy, until mounting evidence supported these drugs in some circumstances. In fact, this extreme reluctance may have been an error, an overcorrection -- a response to the great thalidomide disaster -- but nevertheless this has been the prevailing attitude.
At the same time, we used to understand immediately that life could never be zero risk. We do not counsel immunocompromised patients to avoid all contact with others. We have always sought to achieve tolerable rates of risk. Even without perfect data that risk is 0%, we have encouraged patients, particularly those receiving solid organ or bone marrow transplants to find a balance that is right for them. We have never embraced a philosophy of medicine that means avoid death to the point of giving up living.
The moral asymmetry
COVID-19 has introduced a new asymmetry, one that is perverse, and harms decision making. Folks naturally fall into three categories of prediction. First, the fearful, sky-is-falling predictions. Vaccines might not halt transmission, and they certainty won't work until all kids and most adults (including pregnant women) get vaccinated. At the other end of the spectrum is the idea that things are going to be terrific: cases will fall, even if large swaths of the population remain unvaccinated. The final category is something in between -- we must maximize vaccination amongst the vulnerable, but can await data in pregnant women, and it is possible there may yet be more resurgences in case load.
Of course, all of these three protagonists can be vindicated or proven wrong. But the fundamental asymmetry is that if you are extremely careful because you think the worst will come, and it does not, at least you were careful. Instead, if you took risks, and bad things happen, a popular allegation is that you are aligned with nefarious political interests, and/or support death.
This is a deeply poisonous way to think about medicine and public health. SARS-CoV-2 and vaccination in a population with some significant rate of resolved infection naturally leads to policy dilemmas and trade-offs. Should we advise pregnant women to vaccinate now, or await trial data? Should we reopen schools or wait for lower counts? Can a vaccinated 84-year-old grandmother hug her 5-year-old unvaccinated grandson? If the moral calculus only considers the worst-case scenario of the virus, then we subordinate all other goals and aspirations and joys of people to viral control. We may end up with policy decisions that do not reflect the desires of any individual.
The challenge of evidence interpretation
Medical evidence is always shades of gray. Even randomized trials have error rates and can be . How you make choices in an environment like this? The right method requires consistent interpretations of the data, and demands that scientific questions are not confused for moral ones. Without a doubt, the evidence that vaccines will slow transmission is far more robust that the current evidence that they offer net benefit in pregnancy. I believe time and accumulating evidence will show they are safe in pregnancy, but for the time being, that's a limitation of evidence.
I recently joked online that if the first time you have said, "we don't know..." since the start of the pandemic is, "we don't know if vaccines slow transmission," your compass is faulty. The truth is we have substantive evidence that vaccines will markedly slow transmission; it won't bring it down to zero, but that's ok. Life does not need zero risk to resume normalcy. At the same time, many, perhaps even most decisions, made during the pandemic were made with residual uncertainty. That's not a criticism of all those decisions, but a statement of fact.
In order to have wise SARS-CoV-2 policy, we must upend the moral calculus that considers only the virus and ignores the rest of human existence. We must also recognize when our standards of evidence are inconsistent, as this may alert us to hidden biases in our thinking.
, is a hematologist-oncologist and associate professor of medicine at the University of California San Francisco, and author of .