meningococcal prophylaxis – Pediatric Infection Connection

It's Easter time, when my thoughts turn to chocolate bunnies. Not only do they taste better than real bunnies (well, to think of it, I may have never tested a real bunny), but I have been unable to find any reports of tularemia transmitted from chocolate bunnies.

Although we are clearly beyond the peak of winter respiratory infection season, we still have plenty to think about from last week.

Covid Household Transmission From Asymptomatic Children

A prospective study showed a high secondary attack rate (SAR) for covid in households likely stemming from asymptomatically infected children. The study was well designed to try to answer this question, identifying asymptomatic children in Canada and the US who were tested for SARS-CoV-2 for either non-household contact with a known covid case or as part of routine hospital screening. The study covered a 15-month period, and results were analyzed according to viral variants predominating in the community at those times: 1/31/21 - 6/30/21 was predominantly alpha or mixed variants, 7/121 - 12/19/21 was delta, and 12/21/21 - 4/22/22 was omicron. The authors compared household SAR of SARS-CoV-2 positive children to rates of those who tested negative. There are many nuances to the study, but here's the bottom line:

SARs were higher with younger index cases (< 5yo versus 13 - <18 yo), if the index case eventually developed covid symptoms (versus continuing asymptomatic), and during delta and omicron time periods versus the interval when alpha/other variants predominated. If you have access to the full text of the article, skim the Methods section to get an idea of the tremendous amount of effort involved in collecting this kind of data.

Dengue in Puerto Rico

This past week Puerto Rico health authorities declared a public health emergency due to dengue, the first time this has happened in the territory since 2012. What I'm sure is alarming to those authorities, beyond the sheer number of cases (524) in 2024 so far, is that this isn't peak dengue season. As befitting the mosquito vector, cases tend to rise in the summer when it is wetter. See below, with my apologies for lack of English translation. You can click on the Week 10 report in the PR DOH Arboviral Diseases Weekly Report for the full document.

In other words, the worst may be yet to come. (The dashed red line is the epidemic threshold which is higher in summer/early fall weeks; August usually is the peak month for rain in Puerto Rico.) We can certainly expect cases in the mainland US, including in non-travelers living in Florida and other states that have experienced autochthonous dengue cases in the past.

Meningococcal Group Y Alert

CDC issued another HAN report about increasing cases of invasive meningococcal disease due to group Y, a phenomenon that has been noticed for a couple years now.

Note that the incidence rate is very low; this represents a relatively small number of cases but still quite significant given the severity of meningococcal disease. Now is a good time for frontline healthcare providers to read up about meningococcal disease in general including indications for vaccination and identification of high risk groups, especially for this outbreak: age 30-60 years, Black or African-American descent, and living with HIV; as well as the usual risk factors of close contact with a case, people at the age extremes, certain immunodeficiency diseases such as complement deficiencies, and some college settings. The HAN notice includes many useful links.

How's Your Ventilation?

CDC issued revised guidelines for indoor ventilation to help prevent respiratory virus transmission, including SARS-CoV-2. Take a look and maybe ask your friendly office landlord how your building stacks up.

Apparently I've missed it for a couple years, but CDC also has an interactive tool to see how changes in ventilation may improve viral particle clearance. I disappeared down that rabbit hole playing with it for about half an hour. Note the disclaimer at the top of the web page about some information needing updates, though I think it mostly concerns the old 6-feet social distancing and other recommendations rather than the tool itself. Here are results from a home with intermittent HVAC operation, uncertain filter rating, and running the HVAC system for 1 hour after a 4-hour period of gathering. Better results can be achieved with continuous HVAC operation (i.e. keep it on continuously during times of high occupancy), high MERV-rated (Minimal Efficiency Reporting Value) filter, use of HEPA (High Efficiency Particulate Air) cleaner, and other factors.

However, before you overhaul your home system or threaten your office landlord, note what this is really saying. The outcomes pertain to effectiveness of particle reduction in the air, which is different from measuring whether it lessens transmission of SARS-CoV-2, influenza, RSV, or other viruses. It makes sense that there would be some correlation, but until someone does a more definitive study comparing systems and actual viral infection rates, we don't really know to what degree ventilation efficiency changes infectious disease outcomes. Compare this with the study of secondary household transmission mentioned at the top today's post - a more difficult study design with results more directly related to clinical outcomes than just a study of airborne particles in a laboratory chamber. And, parenthetically, the household transmission study did not include individual home ventilation as a factor, so even those results are incomplete. This is complicated!

Measles Update

Measles marches on in the US and across the world. US cases continue to grow, now at 97 since January 1, fed in large part recently by outbreaks in Chicago: 21 new cases in the past week just in Chicago alone. Here are the latest US numbers and distribution from CDC:

In Search of Easter Candy

Once again my wife and I have used our granddaughter as an excuse to buy Easter candy. She's a picky eater, now the only chocolate bunny she will touch must be dark chocolate without any added flavorings or other adulterations. I applaud her good taste, but perhaps next year I'll do this shopping more than a few days prior to Easter Sunday. I had no trouble finding a multitude of milk chocolate bunnies, some with various additives including peanut butter, salted and unsalted caramel, marshmallow, and other ingredients that I might have considered inedible if presented separately from chocolate. Plain dark chocolate bunnies apparently are almost extinct, definitely at least a critically endangered species.

I should have kept track of my steps and car odometer for this year's chocolate bunny safari, though I doubt even the thousands of steps I tallied will offset my Easter candy ingestion.

Famous golfer Tiger Woods couldn't complete the second round of a golf tournament this weekend due to influenza. Two questions came to my mind immediately, still not answered. But, we have a lot more than golf to discuss this week.

WRIS

I suspect we are a matter of weeks away before I can retire Winter Respiratory Infection Season as a weekly feature. RSV is much less of a factor now, and I won't be discussing much about RSV unless things change.

Influenza-like illness continues to fluctuate regionally, we're really seeing wide variations. I'll mention again that this tracking method will pick up not just influenza, but also other respiratory illnesses. However, pre-pandemic it was a pretty reliable gauge of influenza activity. I do note that Mr. Woods lives in Florida and the golf tournament is in California. He became ill Thursday night, so using the common incubation period for flu of 2-3 days he could have acquired this in California (if he was practicing there a few days before); however, the outer range for flu incubation period is 7 days, so all bets are off about where he met his virus. (Also, I'm not stalking him, I have no idea about his travel history.)

At this stage of flu season, it's worth a look at pediatric mortality numbers. It's a little less than, but similar to, last year. Also note there is a significant lag time in reporting and verifying influenza deaths, so some of these bars in previous weeks will rise.

Pediatric deaths continue to occur slightly more commonly in children without underlying medical conditions, and the 5-11 year age group is the most common. Unfortunately, no data for vaccine status is provided.

What about the covid scene? As usual, I'm still looking at wastewater data because the methodology for collecting and reporting this information hasn't changed as much as have the methods for reporting infections and deaths among the states.

Again, this is at most a qualitative descriptor, but nothing to suggest a new surge approaching. Wastewater activity is highest in the South.

I wish CDC would publish numbers of covid pediatric deaths like they do for influenza. They only report death rates per 100,000 by age, and of course they are very low for the pediatric population. The absolute numbers are somewhere in there, but on the CDC website it would require me to write my own search language in their database, and I'm too lazy to spend the time to figure that out.

I also took a look at CDC's covid vaccine rates by age, especially since they now have updated information regarding the fall XBB vaccine dose. It's pretty grim.

Note that the highest rate is only 13.4%, and when I dug down into more details, all the states except one were in single digits for pediatric populations receiving the updated vaccine. The best and only double-digit rate was Vermont at a dismal 13.4%.

On the other hand, one could argue that because rates of serious pediatric disease with covid are so low it isn't cost-effective to vaccinate children who do not have risk factors. In fact, that's what most countries have decided; the US is an outlier in offering covid vaccine to healthy children. Nonetheless, on an individual basis every child is better off being vaccinated than not, even given the low risk of death, long covid, MIS-C, etc.

Back in the somewhat good news arena, a recent article gave an overview of planning (and funding!) for research on better covid vaccines, monoclonal antibodies, and antiviral drugs that will not be subject to loss of effectiveness with new variants. It's called Project NexGen.

Lastly on the covid front, many of you probably heard about CDC plans to change isolation guidelines for the public to be more in line with what we do for flu and other respiratory viruses. So far it is just a draft, but it's targeted for release in April. It's not really based on any new findings about transmission rates or duration of infectivity, but rather I think an attempt at simplicity with the recognition that current guidelines aren't being followed by the majority of the public anyway. What I think is most important, and I hope the final guidelines will stress, is that guidelines should differ depending on the situation. For example, it's a very different calculus for children attending school than it is for those same children going to visit their 85-year-old grandma. The public needs to understand that different risks occur in different circumstances.

Measles

Hot off the presses, 4 children in a single elementary school in Florida developed measles. So far not much official from the Broward County health department, but I'm betting that none of them were fully immunized. Watch out for a large number of secondary cases in the coming weeks.

Changes in Prophylaxis for Meningococcal Disease

This was news from the previous week that I'm just mentioning now. Ciprofloxacin has been used for prophylaxis of meningococcal disease for several years, but recently some sectors are now seeing resistance to quinolones. So, if you are considering prophylaxis of a close contact of someone with meningococcal disease, you will need to contact your local health department immediately to see if the resistance rate meets criteria for choosing an alternative agent such as rifampin, ceftriaxone, or azithromycin.

Tiger's Third Degree

I look at everything through an infectious diseases eye, whether I'm walking down the street, reading the paper, or chasing squirrels from the bird feeder; I just can't stop myself. So, I have 2 questions for Tiger.

Did you get a flu vaccine this year? I'm not a betting man, and I've already made one bet in this blog, but I'd guess not. He had fever and other symptoms the night before his Friday golf round, and then Friday morning still had fever and other symptoms but tried to play the round, making it through a few holes before feeling faint and ending up with IV rehydration therapy according to his official statement.
And to follow up on the above thought, what were you thinking trying to play the round on Friday? Not only did you not meet any school or workplace criteria for participating, you exposed everyone close to you to influenza presumably without notifying them. Of course, this is the sort of "tough it out" mentality that I've been guilty of myself in the past, at least to the point of working when I had a mild cold because I thought myself too essential for my workplace or didn't want to shoulder my colleagues with covering me. I don't think Tiger needed the money for playing in the tournament, but he also was the host of this particular event and I'm sure many fans turned out primarily because he was playing, so that's a bit more pressure than in my workplace. Still, isn't it time we made a change in our behavior when we're sick? Take a moment to think about the impact your actions have on others.

Which brings me to a third question for Mr. Woods: Would you at least make a statement recognizing that you should not have tried to play on Friday, and also give a plug for flu vaccine even if you didn't receive one this year?

I'd bet big bucks that Tiger Woods doesn't read this blog, so, yes, I'm just blowing off steam.

Next week is the regular meeting of the ACIP, I"m hoping to view most of the 2-day meeting and have this be the focus of next week's blog.

Tag: meningococcal prophylaxis

Chocolate Bunnies