Last week I was struggling to come up with enough new items to fill the post; this week I'm wrestling to pare down the list of topics. We've had some more concerning news about autochthonous tropical infectious diseases cropping up, but before I turn to that....
Is Covid Coming Out of the Doldrums?
Lots of headlines about this in the past week, some more hysterical than others. Staying alert, not panic, is the appropriate response.
First to wastewater. Looking at the past 6 months in Biobot, every US region is trending up, notwithstanding a slight drop in the purple midwest region.
Now look at the same graph spread out over a longer time:
So yes, we've had an upward blip recently, but nothing as dramatic as what accompanied serious clinical outbreaks in the past.
The other hype is about newer variants. Fortunately, we're still talking about omicron and primarily from the XBB subvariant group. I'll turn to the UK's nice graphs to highlight; results are similar but not identical to the US.
This Sankey diagram gives you an idea of the relatedness of strains:
The key question is how well the proposed autumn covid vaccine, derived from XBB.1.5, works against these newer variants. The answer is based mostly on conjecture at this time, we have no peer-reviewed hard data yet. The best guess is that it will not protect much against infection itself, nor will prior natural immunity. However, for the more important protection against severe disease, hospitalization, or death, it is likely to have an impact. Jennifer Abassi, a medical news reporter for JAMA, published a nice discussion. CDC and IDSA recently posted a brief explanation. Also in the news the past few days has been a newer variant, BA.2.86, now seen in a few countries sporadically including the US. It's much too early to know if this will become prominent.
CDC published updated data about monovalent and bivalent vaccination in the 6-month to 4- or 5-year-old age groups that showed good effectiveness in protection against urgent and emergency care visits. Also important to note is that these are relatively uncommon events in this age group, which is why you see different recommendations for vaccination in the US versus the UK for example. Going from the last section of Table 2 in the article, rates of these care visits from 12/24/22 to 6/17/23 were 4.4% in the unvaccinated group versus 0.9% in those who had received at least one bivalent vaccine dose. With a little arithmetic, the number needed to vaccinate at this level to prevent one additional ED/urgent care visit is about 30.
Reason to Avoid Proton Pump Inhibitors
French investigators published a cohort study linking use of PPIs in children to higher risk of serious infections. It included over 600,000 children receiving PPIs and a similar number as a control group not receiving PPIs, followed for a few years. The risks for serious infections as well as a number of categories of infection types were significantly increased. Most of the children had significant comorbidities. This association has been known in adults for a long while and is likely based on a variety of PPI effects including elevated gastric pH and alteration of the GI microbiome. That's not to say PPIs shouldn't be used in children, but there is a clear risk that should be explained to parents.
RSV Already in Florida
Florida is now seeing RSV infections in some jurisdictions. This isn't too surprising; Florida has a very different seasonal epidemiology than does most of the US:
It remains to be seen how RSV seasonality will stabilize in the post-pandemic/isolation era. A group in the Netherlands recently reported a switch to year-round transmission during the pandemic.
Along similar lines, a US study showed that ICU admissions for RSV consisted primarily of infants without risk factors; the study does have significant limitations. Findings may reflect the lack of partial RSV immunity conferred by prior RSV exposure of both mothers and infants.
It's still time to plan for use of monoclonal antibody and, if approved, maternal RSV vaccination. AAP and ACIP have a nice discussion available. Lots of logistical hurdles remain.
Autochthonous Malaria and Dengue
I posted about autochthonous malaria in Florida and Texas on July 2 and 9, and on autochthonous dengue fever in Arizona on 11/20/22. See the July 2 post for more about the definition of autochthonous infections.
Now we have a report of 11 autochthonous dengue cases in Florida. Closer to home, we've had a report of 1 case of autochthonous P. falciparum in a Maryland resident in the National Capital Area region. Falciparum malaria is significantly more dangerous than the vivax forms reported in Florida and Texas. Very little information was provided, but the letter does have links to good clinical information sites.
Autochthonous infections are tricky to diagnose given the lack of travel history to an endemic area. Climate change has expanded the geographic range of many insect vectors of disease. All clinicians should be aware of these diseases when evaluating febrile patients.
As a final note, my web wanderings about autochthony taught me something new about the term. Sadly, it has been used in a negative political (and racist) sense. An "autochthonous" flag protest disrupted a 2014 soccer match between Serbia and Albania.