Living in the DC area, it's impossible to ignore the news on the looming debt ceiling deadline. Thankfully, we don't have a lot of infectious diseases causing immediate worry.
It's RSV Week
No, we haven't had any bizarre spring outbreak of RSV disease, just a spring outbreak of RSV news.
I wasn't able to view the FDA VRBPAC meeting about the Pfizer RSV vaccine for pregnant women, but I've gone over the documents, slides, and news reports. From a superficial view, the committee members voted unanimously that the vaccine, administered to pregnant people at 24-36 weeks gestation, was efficacious in preventing medically-attended lower respiratory tract infection (MA-LRTI) in their newborns from birth through 6 months of age. They also voted that the vaccine was safe, although 4 of the 14 panel members voted "No" for the safety issue.
Looking at the efficacy numbers, the vaccine efficacy was 57.1% (95% CI 14.7-79.8%) for RSV+ MA-LRTI and 81.8% (40.6-96.3%) for severe (defined as tachypnea, oxygen desaturation, need for high flow cannula or ventilatory support, ICU admission, or unresponsiveness) RSV+ MA-LRTI. The main trial involved about 7000 mothers, randomized equally to vaccine or placebo. As you can see, the confidence intervals are quite large, indicating the relatively low numbers of the outcomes of interest. Efficacy for severe disease dropped to 69.4% at 6 months of age, again with a wide confidence interval. The numbers are pretty good for a respiratory viral vaccine. Here's a screenshot of one of the FDA presentation slides for severe disease:
For safety evaluation, both mothers and infants were studied. The main concern that arose had to do with a higher rate of premature delivery in the vaccine group. Here's the safety summary from the FDA presentation:
You can see that the premature births/deliveries percentages are close to one another, and the differences did not reach statistical significance. Still, it is notable if in fact there is some causal association - remember, it would be a vaccine potentially given to all pregnant people. Also, it's a bit more concerning because over a year ago GlaxoSmithKline paused their trials of a maternal RSV vaccine over safety concerns. The safety concern with the Pfizer vaccine would likely require tens of thousands of participants in new clinical trials to have enough power to see if the relationship holds; rather, this would be something to focus on with post-marketing surveillance if the vaccine is approved.
At the time I write this, FDA has not yet issued an approval statement for the vaccine. Of course, we have plenty of time since the next RSV season is likely months away. Also, we must remember there is another potential new alternative for RSV severity mitigation in young infants, the long-acting antibody preparation nirsevimab. The CDC's ACIP will discuss maternal/pediatric RSV prevention at their meeting on June 22. It may be that nirsevimab is a better choice than vaccine at this point. I'll be very interested to follow that June ACIP meeting.
But Wait, More RSV
A couple new studies appeared last week. One longitudinal cohort study in Tennessee demonstrated an association between lack of RSV infection in the first year of life and lower risk of asthma developing within a 5-year followup. This isn't the first study revealing that early RSV infection can lead to subsequent asthma diagnosis. The study involved only term infants, suggesting significant potential benefit of RSV preventive measures beyond just premature infants.
Another study from Colorado reported that lack of exposure to RSV during the bulk of the covid pandemic could be the reason we saw such a severe RSV season this past fall and winter. We'll need to see the results replicated in other locales, but the study was well done and the mechanism is biologically plausible.
Covid News
Not much has changed in the past week, but a few items of interest appeared. First, the World Health Organization has recommended the next iteration of vaccine be a monovalent product targeting the XBB lineage, abandoning any inclusion of the ancestral strain. I'll be interested to see if the US follows suit when FDA meets June 15 to discuss composition.
A recent modeling study also caught my attention. As I've said before, modeling studies have many assumptions and can end up being totally off base, but this one from multiple institutions shows that, if we had done a better job with covid booster vaccinations in fall of 2022, we would have seen a significant decrease in both hospitalizations and school absenteeism in the pediatric population last winter. Perhaps I'm cherry-picking this study because it agrees with my bias that covid vaccination benefits all age groups, but the study methodology seems sound given the limitations of any modeling study.
Lurking in the Shadows
Mpox remains a problem, particularly for men who have sex with men. The vaccine is highly effective.
Influenza H5N1 continues to lurk, causing sporadic infection primarily among those with very close contact with fowl including chickens. The US Department of Agriculture is studying a vaccine for poultry as well as use of other mitigation strategies.
CDC has some new guidance on building ventilation, maybe one of the lessons learned from the pandemic that would be useful to implement now in your office and/or home, depending on need and available financing.
I'll keep my eye on all these shadows, but in the meantime I'm turning my attention to a more practical matter of my carport's battle with carpenter bees. Listen to the soundtrack in the link, it sounds like it came from a bad horror film.