Covid-19 updates from "ID Week." New research that made me think.

Last week, I went to Los Angeles for “ID Week,” the national conference of the Infectious Diseases Society of America. I spent very little time in the large lecture halls where respected and famous experts gave talks on a variety of topics. Instead, I spent much more time walking through the hall where hundreds (and maybe thousands) of research posters were on display. The posters summarized new findings that teams around the world wanted to share with conference attendees like me—things that are interesting, promising, and unpublished. Think of it as a science fair for grownups.

There were a substantial number of posters presenting new Covid-19 research from all over the globe. This was encouraging to see, because the major medical journals seem fairly burned out on publishing new research on the topic. So, it was good to get a sense of what questions other researchers are thinking about.

Interested in joining me for a few highlights? Let’s get started!

How well did Evusheld work for immunocompromised people during the Omicron subvariant era?

Evusheld is a cocktail of two Covid-19 antibodies. It was the first FDA authorized treatment used to prevent Covid-19, and it was available for immunocompromised people in the US from early 2022 until early 2023. It was taken off the market because in laboratory studies, the antibodies were found to bind far less well to the Omicron subvariants that had emerged compared to earlier variants. But there were no clinical data showing that Evusheld no longer worked.

An ID Week poster from Thailand described a study looking at the effectiveness of Evusheld among organ transplant recipients from August 2022 through February 2023. They found a few interesting things. First, around 17%-19% of the patients contracted Covid during the six-month study period, which is quite high considering that Thailand’s rates of Covid at that time were relatively modest. This implies that immunocompromised people struggle to keep SARS-CoV-2 from taking up shop and causing productive infections (not a surprise). Second, the patients did pretty well, with mostly mild illness. That is a great sign for such a high-risk group. But the third finding requires a bit more analysis. The researchers found that by the end of the study, there was no difference in infection rates between people who received Evusheld and controls who did not. That would imply that the FDA made the right call back in 2023. But here’s the thing: The curves in the graphs split early; in the control group, all infections had occurred by day 70 or so. In the Evusheld recipient group, all infections had occurred by around day 120 or so. That implies the injection worked, but that higher or more frequent dosing might have been useful. (It also implies something about the waves of Covid during the study, but I’ll leave that aside.)

While we now have a new similarly designed preventative treatment for immunocompromised people called Pemgard, I still wonder whether Evusheld had a genuine use in 2023 (and even now), and whether it should still be used as one tool in the kit. (Poster author: Gun Rojankit and colleagues, Ramathidbodi Hospital, Bangkok Thailand.)

Heart failure and Covid-19 hospitalization.

Before the Delta variant era of the Covid pandemic, we’d see patients of all kinds being hospitalized. Certainly the risk was higher in people with medical conditions like diabetes, cancer, and heart failure (a chronic condition marked by decreased blood pump efficiency), but I can’t emphasize enough that we also saw otherwise healthy adults getting hospitalized whom we’d never have expected to see get so sick for any reason. But due to the combination of vaccines, immunity from prior infections, and changes in disease severity due to new variants, things were different by the time the Delta variant hit my part of the world. We no longer saw very sick people who otherwise wouldn't have darkened the doors of hospitals. Instead, we saw people who were at high risk of getting of hospitalized in, say any given year, but who were getting hospitalized and dying a lot more than usual (i.e., excess hospitalizations and excess deaths). An ID Week poster summarizing research from Singapore demonstrated this well. Researchers found that patients with heart failure and ischemic heart disease had higher hospitalizations rates than those without those conditions (not a surprise) and that the risk relative to controls increased during the Omicron wave compared to the Delta wave. During the Delta wave, patients with heart failure had a 40% higher chance of a Covid-related hospitalization. During the Omicron wave, it rose to 77%. Boosters were found to decrease the risk of hospitalizations in these patients. (Poster author: L.E. Wee and colleagues, the National Centre for Infectious Diseases, Singapore.)

Unexpected cardiac deaths and prior Covid-19 infections.

There’s no doubt that for people with heart disease, getting Covid-19 can be very dangerous. Covid, like any serious virus (including influenza) can dramatically increase the chance of a heart attack during the first few days following an infection. (As above, episodes like this probably drive a sizable portion of serious Covid-19 outcomes these days.)

The question is what happens after people recover. There’s a body of literature suggesting that after people recover from Covid-19, they carry increased risks of heart attacks for weeks, months, and even years. The problem with those data, however, is that the control groups used in those studies were rarely limited to people who verifiably did not have Covid. Rather, they included some people who didn’t (i.e., the correct control) and some who actually did have Covid, but the cases were so mild that they never sought care (i.e., not truly controls)—thus their cases did not show up in large medical record databases. As a result, the only reliable conclusion I can take from studies like those is that people who were sick enough to have their Covid illnesses diagnosed in medical settings (like hospitals) were more likely to have heart problems than those who were not sick enough to have been diagnosed like that. In other words, the increased rate of heart problems in those studies likely indicates more about who the patients were when they were diagnosed than it does about the lingering risks that Covid itself leaves behind.

An ID Week research poster by epidemiologists in Qatar (some of whom I have collaborated with in the past) looked at this a bit more rigorously. The big advantage to research coming out of Qatar is that for much of the pandemic, workers were required to have negative tests in order to report for duty. That means that researchers could “build” control groups that were comprised not merely of people who never had a Covid diagnosis in the database, but, rather, of people who had lots of negative tests during whatever period they were studying. Yes, some people might have had mild cases slip through the cracks, but it was a lot less common. As a result, the researchers were able to compare people who had positive tests (including many who were picked up during routine testing, not due to illness severe enough to get them to go to a medical setting) to those who had negative tests. Using that approach, the researchers found no increase in unexpected sudden cardiac deaths among relatively young Covid survivors (average age of around 50) compared to similar people who had not gotten Covid during that time. This argues that the increased heart disease risks due to Covid is likely to be temporary. If that’s true, it’s great news. (Poster author: Adele A. Butt and colleagues, Weill Medical College, Doha, Qatar.)

Questions? Comments? Join the discussion!