Coronavirus: One possibility

There are many possible explanations for why the severity of COVID seems to be declining, and that the case fatality rate is plummeting. These include variations in susceptibility, genetic mutation of the virus, different strains, etc. Another possible explanation is that most of the COVID-19 deaths involved pneumonia. It is possible that the decline in mortality is a consequence of the the decline in pneumonia among those infected with SARS-CoV-2, and that this in turn is a seasonal phenomenon. Perhaps environmental factors in warming weather change the risk of developing pneumonia, and make late spring-early summer infections less lethal. Given that these may contribute to heard immunity, a spike in cases in the summer months, particularly among younger people, may in fact lessen the severity of COVID in the fall and winter.

Coronavirus: Dilemma

One possibility exists that presents a real dilemma for public health officials: that a greater number of infections in midsummer will mean a less severe resurgence in the fall and winter. It may be the case that the best management over the long term is to intervene as little as possible.

Another dilemma may arise from the strategy of waiting for a vaccine before relaxing interventions meant to control spread of the virus. What if there is a vaccine but it only has the same efficacy as the typical flu vaccine, say 25% to 30%? Is that good enough? What if the vaccine is needed more than once a year to maintain protection? Should behavioral interventions continue? 

Coronavirus: Second wave

There is a great deal of hand-wringing regarding the recent resurgence in coronavirus cases in the United States. There is also consequently a great deal of finger-pointing and claims of mis-management. Before getting too far into discussing how policy is related to the trajectory of corona-virus cases, one should quickly look at the number of cases in disparate countries such as Israel, Sweden, Saudi Arabia, etc. There has been an upswing in cases in locales representing the spectrum of interventions. The simplest explanation for this is that the virus gets a vote in how it spreads, and such spread is largely insensitive to interventions meant to control it. This, if nothing else, suggests that the interventions accomplish little.

As was mentioned several weeks ago on this blog, the expectation is that the severity of disease will decline prior to the pandemic abating. This is what is, in fact observed. the typical explanation of this is that the genetic mutations account for his phenomenon, but such is not essential to predicting that this would happen. We don't know why the severity of disease declines, but on possibility is that it is not a genetic phenomenon, but an epigenetic one. It may result from the interaction of the virus with the environment, humans, and communities. Whatever the case, this latest resurgence in COVID-19 does seem more characteristic of "a bad flu" than did the earlier infections.