It's nice to be back after my brief website repair hiatus. Please let me know if you have any problems or have any suggestions for the website. I'll continue to work on design issues.
I won't attempt to cover all the issues in pediatric infectious diseases appearing during the hiatus. Needless to say, at lot happened, mostly old news by now. Some newer things I won't mention because they appear only in abstract form at national meetings, such as this month's ID Week (Infectious Diseases Society of America and other ID groups) and the American Society for Tropical Medicine and Hygiene. I have seen dramatic changes from the time data are presented at a meeting, which can be preliminary and incomplete, to the final publication or lack thereof. I've become averse to propagating that type of information source.
Yellow jack is another name for yellow fever; it takes its name from the yellow nautical flag that alerted others that yellow fever was on board. A variation of this flag is still used today to alert other ships about health issues on board. You might want to brush up on your yellow fever knowledge now, keep reading if you're intrigued.
Nirsevimab Supply Chain Flop
This isn't news to any practicing primary pediatric healthcare provider. The supply of the newly-approved long-acting monoclonal antibody preparation to prevent RSV infection for all infants has hit a major snag: demand has far outstripped supply. Maybe we will eventually hear the true story of what happened, but basically we are dealing with a single manufacturer who couldn't produce enough product. Even some hospitals aren't able to get a supply to administer to newborns at the time of discharge.
The AAP has a nice RSV page that healthcare providers may find useful, as well as an October 17 webinar with practical strategies. Remember that maternal RSV vaccination at 32-36 weeks gestation is another option to encourage; talk to preganant people visiting your practices. Palivizumab (Synagis) is still available for high risk infants.
Tripledemic Update
We're certainly not anywhere close to a tripledemic at present. Only RSV seems to be on a significant upswing:
Flu season hasn't yet started for most of the country. COVID-19 disease is much more difficult to track now that our tracking methods have changed so dramatically from the pandemic area. I look to wastewater reports as the most consistent indicator over time, and they suggest that we did not have a big spike this fall.
Future Pandemic Preparedness
The Journal of Infectious Diseases finally got around to publishing a supplement on vaccine and monoclonal antibody development for potential future viral pandemic pathogens. It was put together from presentations at a meeting in 2021. Here's a quick overview of the types of pathogens considered:
Comparison of pandemic potential and countermeasures for viral families known to infect humans. Viral families were categorized as having either low/moderate or high pandemic potential and low/moderate or high levels of existing resources and countermeasures. Cross-comparison revealed 10 viral families with high pandemic potential and low/moderate existing resources or countermeasures upon which the National Institute of Allergy and Infectious Diseases will focus its pandemic preparedness activities. Asterisks denote existing vaccine solutions for some viruses in that family; boldface type, potential vaccine solutions for the entire virus family; shaded box, viral families chosen for prototype pathogen selection.
I'm sure many of these names except for Coronaviridae are unrecognizable to most physicians, and several at best are vague even for infectious diseases specialists. Orthomyxoviridae include influenza viruses. Let's hope research funding comes through for the entities in that lower right box.
Yellow Fever
You probably haven't thought much about yellow fever unless you've considered travel to an endemic area, either for yourself or for patients in your practice. We have an effective vaccine available, but it is a live virus vaccine. Risks for vaccine side effects increase with age greater than 60; I actually received yellow fever vaccine for travel when I was in this high risk group; more on that later.
A recent Perspective essay in this week's New England Journal of Medicine raised the possibility of yellow fever reappearing in the US, particularly in the southeastern United States. This is already a problem with other mosquito-borne infections like dengue, chikungunya, and Zika viruses. (Note these are in the family Flaviviridae, also included in the gray box above.) The vectors for yellow fever, Aedes aegypti and A. albopictus, are well represented in the US, and their range is increasing as our climate warms.
Yellow fever is endemic in some parts of South America and Africa, and its range appears to be spreading in recent years. (The maps below are a few years old, updated WHO country recommendations usually are published in November.)
Diagnosing yellow fever without a travel history will be very difficult in most instances. In about 85% of those infected, the clinical presentation is a self-limited, nonspecific febrile illness with chills, myalgia, headache, and some GI symptoms lasting about 3 days. An unlucky 15% have a more biphasic presentation with the second stage appearing after around 48 hours of improvement and characterized by more severe symptoms including jaundice, renal failure, coagulopathy, and other life-threatening problems. At that stage the diagnosis might occur to an astute provider and diagnostic testing can be obtained. No specific antiviral therapy is available.
Yellow fever vaccine is highly effective, and a single dose confers life-long immunity. It is relatively safe, but there are rare severe side effects. These severe reactions are 3- to 4-fold higher in vaccine recipients over 60 years of age:
Yellow fever vaccine associated neurologic disease (YEL-AND; mostly encephalitis, Guillain-Barre syndrome):
- over 60 years of age = 2.2 cases per 100,000 doses of vaccine administered
- less than 60 years of age = 0.8 cases per 100,000 doses of vaccine administered
Yellow fever vaccine associated viscerotropic disease (YEL-AVD; similar to severe infection itself with approximately 50% mortality):
- over 60 years of age = 1.2 cases per 100,000 doses of vaccine administered
- less than 60 years of age = 0.3 cases per 100,000 doses of vaccine administered
I was over 60 years of age when my travel to Ethiopia caused me to consider yellow fever vaccine. My reasoning wasn't based on the 3- to 4- fold increase in risk, which is a relative risk increase, but rather focused on the absolute risk. This is a topic I've revisited many times in this blog; it has immediately applicability to vaccination of any type but especially for COVID-19 and RSV now.
Adding together the risks for YEL-AND and YEL-AVD for the older population comes to 3.4 cases per 100,000 vaccinations, or 0.0034%. As a comparison, risk of airplane crash is about 1 in 11 million (o.oooo1%) and risk of being struck by lightening is 1 in a million or less (0.0001%). Of course these risks vary by how many miles you spend on airplanes and how often you are out walking around in thunderstorms. Weighing my yellow fever vaccine risks and benefits, I chose to receive the vaccine rather than not travel to Ethiopia where my specific yellow fever risk was very low because I was staying at high altitude for most of the time.
Speaking of Travel
I timed my blog hiatus with a major trip to the Umbria region of Italy. It was a hiking vacation through rural areas with occasional forays into medieval towns and was a wonderful experience. I'm still nursing a few minor musculoskeletal aches and pains - my muscles and joints aren't what they used to be.
In addition to beautiful churches, ruins, and the medieval towns, I was also surprised to see many unfamiliar butterfly species including this Hipparchia hermione example.
