Well, vaccines are starting to turn the tide and even the cicadas are retreating now. I'm hoping to recommit to Pediatric Infection Connection this summer and try to post weekly commentary that will be at bit more concise than my traditional rambling style. I will try to limit myself to just 2 topics a week, but starting off I'm already breaking that pledge with 3 topics.
1. A Conflict of Interest
For the first time in maybe a couple decades, I need to declare a conflict of interest up front. I am overseeing the Pfizer COVID-19 vaccine trial at Children's National Hospital for children 6 months through 11 years of age. While I don't think this will color any of my commentary here, implicit bias has been recognized as a confounder in scientific and Evidence Based Medicine circles for many years. I will do my best to recognize that and be objective.
2. Keeping Straight with SARS-CoV-2 Variants
In case you hadn't noticed, the terminology for variants has changed yet again, I think for the better but also adding to the public confusion. The purpose is laudable: eliminating the possibly pejorative naming of variants by site of first detection and also doing away with confusing codes. I'm very much in favor of getting rid of the geographic references to outbreak agents. Some of you know that the 1918 H1N1 influenza A pandemic was also known as the Spanish Flu, but in fact the evidence would suggest that a better name is the Kansas flu. Such nomenclature opens the door to discriminatory practices.
Now we are just using Greek letters for SARS-CoV-2 variants, though I fear we will run out very soon! The CDC has a summary of these.
I want to focus on the delta variant which has been the focus of much attention in the lay press. This variant is officially a "variant of concern" and is very much worthy of concern. I don't think it is oversimplifying to focus principally on 3 features of variants. First is transmissibility, or how easily the variant can spread in a population. As the pandemic has evolved, probably the most accurate early sign of transmissibility is how quickly a new strain becomes predominant in a population. The delta variant is striking in its spread, now the most common variant in the UK and soon to achieve that status in the US. It is clearly more contagious than the original strain and early variants.
The second feature is virulence, or whether the variant causes higher rates of severe disease and death. In my opinion, the jury is still out on this for the delta variant. Certainly we have seen appalling severity of disease with this variant in India, but I cannot sort out from the reports how much of this could be due to properties of the virus itself versus healthcare access and other issues.
The third, and perhaps most fearsome to those residing in highly-vaccinated communities, is whether the variant is able to evade host immunity and cause a higher rate of infection in those who have immunity from either natural infection from another SARS-CoV-2 strain or from immunization. In this regard, the delta variant clearly can evade immunity to some extent. Thankfully full vaccination seems to protect from severe disease, but partial vaccination is much less effective. It really causes concern for all those people who skipped the second dose of the Pfizer or Moderna vaccines.
Also remember that every person who is infected with SARS-CoV-2 represents a new opportunity for new variants to appear.
Myocarditis and COVID-19 Vaccines
We must be certain that these new vaccines are safe, and in particular that the risk/benefit ratio is favorable. This is especially important for children where, although severe COVID-19 and MIS-C cases occur, the rates are much lower for complications than for adults.
The CDC had planned an update on myocarditis cases associated with COVID-19 disease for June 18, but this was postponed for a week due to the new Juneteenth national holiday. Now it is to be incorporated into the regular meeting of the ACIP scheduled for June 23-25.
However, based on the data that have been released so far, it does seem increasingly plausible that one or more of the COVID-19 vaccines can cause myocarditis. They are still so rare that it is difficult to be certain that it is happening above the expected rate of myocarditis from other causes in the population. It is unlikely to be anywhere near as common as the rates of myocarditis from natural SARS-CoV-2 infection and thus at this time suggests a clear benefit from vaccination. If you're interested, check out a nice study of COVID-19 myocarditis in Big 10 conference athletes.
Stay safe and enjoy the summer!