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Tag: omicron variant

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Published on 2 Comments on Less Illness, More Chatter

We've had a slow week of infectious diseases events, but that hasn't slowed down the chatter and noise. I've tried to distill out the more important topics this week.

The Covid Front

Even though US tracking systems have been greatly dismantled in many states, I can still safely say we are in a lull. Naturally, thoughts turn to predicting the next surge and how to mitigate it.

I mentioned in my May 5 post that the FDA's Vaccines and Related Biological Products Advisory Committee meeting to decide on composition of the next iteration of covid vaccine would be held on May 16 and likely would make the same decision as the WHO already has, using the JN.1 variant. However, they suddenly postponed this meeting to June 5. FDA didn't offer an explanation for the postponement, but the last-minute change leads me to suspect that they wanted a little more time to think about newer variants with possible significant differences in immune-escape properties. Here's a deeper dive into that.

As you can see in this latest CDC variant report, the dark purple JN.1 proportion is decreasing, with KP.1 and KP.2 starting to expand. Both of those are in the JN. 1 lineage:

All of the JN and KP variants are informally called FLiRT variants, an easier shorthand than trying to remember all the letters and numbers. It stands for amino acid substitutions, in this case phenylalanine (F) substituted for leucine (L) in the 456 position (F456L) and arginine (R) to threonine (T) in the 346 position (R346T) in the spike protein genomic code. These 2 mutations are in antibody binding sites that neutralize the virus, and the mutations make SARS-CoV-2 less vulnerable to vaccine- and infection-acquired antibodies. A JN.1-derived vaccine likely would offer some protection, but perhaps by the June meeting we'll know a bit more about all of this. If they do recommend using KP.2 instead of JN.1 for example, I don't think there would be a significant delay in mRNA vaccine production by Pfizer and Moderna, but it might cause problems for other vaccine platforms such as the one used by Novavax, the other approved vaccine in the US which is an adjuvanted protein subunit vaccine. I'll be watching as much of the June 5 meeting as I can.

HPAI

Now we have a grand total of 2 people in the US infected this year with Highly Pathogenic Avian Influenza, along with a lot of cattle and other animals; a recent MMWR provides details. The new, improved CDC website has lots of helpful links. The second case, in Michigan, was similar to the first human case of A H5N1 infection in Texas - very mild illness with conjunctivitis as the primary symptom. This strikes me as very unusual for evolving epidemics in that usually the more severe cases are identified first because they are more likely to come to medical attention. Both of these cases were identified through surveillance of dairy workers which suggests to me that currently HPAI in humans is a very mild infection, possibly with high rates of asymptomatic infection. This is a good thing generally, but also problematic for tracking infection rates. The MMWR reports only 350 exposed dairy workers are being followed, a very small number. Ideally we'd have more tracking of cattle and dairy workers, regardless of illness or exposure to infected animals. Getting cooperation from dairy farms will be difficult, we're talking about livelihoods in an industry where a shutdown for a cow outbreak could send someone into bankruptcy.

I'm watching multiple feeds to keep up with all of this. A report in NEJM last week was encouraging - heat inactivation of spiked milk samples significantly lowered infectivity in mice fed the milk.

Also in the good news department, USDA reported preliminary findings on HPAI detection in muscle tissue of culled dairy cows. 95 of 96 samples tested so far were negative by PCR. Note that these were condemned animals, none of the meat entered the food supply.

On the somewhat negative side, more cattle herds have been hit with the virus, according to USDA.

Poultry outbreaks also continue with Minnesota registering more detections last week. Note that backyard flocks are not immune to HPAI.

On a slightly related topic, I was disappointed but not surprised to learn that the World Health Assembly, the decision body for the WHO, removed a pandemic preparedness treaty that was to be discussed at their meeting starting May 27. It appears that political considerations caused the cancellation; much misinformation is circulating, especially in the US. The treaty would help countries design programs for pandemic preparedness and in no way allows the WHO to control countries' own public health programs as claimed by some sources.

Potpourri

A scattering of reports might be interesting for readers. First, beware of undercooked bear meat. Six out of eight people who consumed undercooked, previously frozen black bear meat developed trichinellosis. Freezing doesn't kill Trichinella parasites. Beware the (undercooked) bear.

CDC released a Health Advisory Network alert for meningococcal disease in Saudi Arabia, although this is pretty much routine for this time of year during religious pilgrimage season. Travelers to the region should be immunized for meningococcal disease, which is more easily transmitted in the crowded situations during Islamic pilgrimages to Mecca.

Speaking of Noise

I'm pretty sure I've never mentioned this in the blog, probably because I'm so embarrassed, but I'm a 2-time harmonica school dropout. This last exit was due to a combination of my inability to master bending notes on the diatonic harmonica and the fact that my dog runs away from me every time when she hears my mellifluous tones. I've now solved the second problem by clearing a practice space in my trash-heap of a basement where the dog can't hear me, but bending will still be a challenge. It's a technique to hit notes that are in between standard notes; there are maybe hundreds of online instruction sites for how to form your mouth to do this, but basically it's just trial and error and takes several months for most people.

Graphic courtesy of Luke.

Maybe by announcing my intentions I'll be shamed into pulling it together this time and can return to harmonica school. I can't promise to report on my progress, especially if I have none!

Published on Leave a comment on Obstinacy or Ignorance or Fear

Those words written by a famous children's author in 1988 remain relevant today; details to follow after a few mentions of other pediatric infectious disease news from the past week.

Covid Serology Update

The Infectious Disease Society of American updated their guidelines for use of covid serology testing. It is the 4th update since the pandemic began, but there isn't much new here. Currently over 95% of the US population has evidence of immunity either from natural infection, vaccination, or both. Serologic testing of individuals mostly is discouraged because it won't provide any useful clinical information to manage an individual's situation. About the only use might be to check immunity in immunocompromised individuals to help decide if immunotherapy could be warranted for prophylaxis or for treatment of active infection.

Covid in Young Infants

Early in the pandemic, most very young infants diagnosed with SARS-CoV-2 infection were hospitalized. This was due to a combination of the usual practice for febrile infants less than 1 month of age as well as the uncertainty of infection outcomes in this age group. I recall from my clinical experiences that it appeared that most young infants actually did well, though there were exceptions. Finally we have a study that gives us some more detailed data about young infants early in the pandemic. It is a secondary analysis of a prospective global study that recruited children presenting to pediatric emergency departments with illness and tested for covid. The study design allows for much more detail (and presumably more validity) than the other designs such as review of administrative data. The study (actually 2 studies combined) enrolled between March 2020 and February 2022. They ended up with 432 children testing positive for covid to compare with 616 testing negative. Clinical outcomes were generally more severe in the SARS-CoV-2-negative infants:

So, at least early in the pandemic, young infants with SARS-CoV-2 infection fared pretty well.

A Colorful Variant Update

Nothing new about this, but I admit to a strange attraction to colorful covid variant charts. I thought it was interesting to look back to see how the JN.1 variant progressed in the US.

The JN.1 shade of purple has been called "indigo purple" (hex #660999).

Varicella Misdiagnosis

A new CDC report suggests clinicians aren't too skilled in diagnosing varicella infections, perhaps because it is now much less common due to effective vaccination. The Minnesota Department of Health looked at suspected varicella cases from 2016 to 2023, a time when they implemented a new system for processing PCR testing of lesions. Of 208 suspected varicella cases, only 45% had positive tests; in vaccinated patients, the number dropped to 22%. They attributed this to unreliability of clinical diagnosis of varicella, especially in vaccinated patients, but I suspect other factors (improper specimen collection technique, testing unlikely varicella patients "just to be sure") may be contributory as well. Anecdotally I've certainly noticed how difficult the diagnosis varicella-zoster virus infection can be for younger clinicians who don't have the experience of seeing multiple cases in the pre-vaccine era.

Speaking of Misdiagnosis ...

I'm in my broken record mode again here. In case you've been hibernating or torporing, we're in the midst of a global measles surge. I read with alarm of a measles vaccine shortage in Canada. There are no signs of a similar shortage in the US; you can always check on US vaccine shortages at this CDC site. With spring break upon us now, and summer travels coming up, all of us need to brush up on measles diagnosis. Thankfully we have a lot of help.

Last Sunday, the CDC issued a Health Alert Network post with a number of useful links. The American Academy of Pediatrics provides a one-pager with great advice as well as a 5-minute video. Another source I've found very useful for years is from a now out-of-print textbook, Krugman's Infectious Diseases of Children. When I discovered libraries no longer carried it, I tracked down a used copy of the 10th edition (1998) released by a university library and have made continued good use of their black and white diagrams. Here's the clinical progression of illness, the key highlight here is the prodrome of a few days before the rash appears. This is very helpful in suspecting a measles diagnosis because the prolonged prodrome is very unusual in pediatric infectious exanthems.

Also useful is the development and distribution of the rash:

I failed to find a current global measles map so return to the CDC website to at least give a current view of US measles cases. For this calendar year we are now up to 64 cases spread over 17 jurisdictions.

Many clinicians may not remember that, though the first measles vaccine was approved for use in the US in 1961, it wasn't until 30 years later that a second dose was recommended. That was spurred by cases in the late 1980s appearing in vaccinated school children, the first major sign that a single dose wasn't sufficient to prevent outbreaks. That second dose was first recommended for 11-12 year olds by the AAP, subsequently dropped to the 4-6 year age group in 1997 to come into agreement with the CDC. Importantly, the interval between the 2 doses can be as short as 28 days for MMR and 90 days for MMRV vaccines, and early vaccination down to 6 months of age is indicated in special circumstances, such as for children who will be traveling internationally. Frontline pediatric providers need to be proactive in alerting parents planning international travel to ensure that their children ages 6 months and older are protected. Scroll down to the Special Situations section on the CDC immunization schedule notes.

Roald Dahl

I learned just recently that this famed children's book author lost a daughter to measles in 1962. He wrote 25 years later, "Olivia, my eldest daughter, caught measles when she was seven years old. As the illness took its usual course I can remember reading to her often in bed and not feeling particularly alarmed about it. Then one morning, when she was well on the road to recovery, I was sitting on her bed showing her how to fashion little animals out of coloured pipe-cleaners, and when it came to her turn to make one herself, I noticed that her fingers and her mind were not working together and she couldn’t do anything. 'Are you feeling all right?' I asked her. 'I feel all sleepy,' she said. In an hour, she was unconscious. In twelve hours she was dead.”

She had developed measles encephalitis. He wrote this in the late 1980s to encourage parents in the United Kingdom to accept a new MMR vaccine for their children (monovalent measles vaccine had been introduced in 1968 in the UK). He also wrote, “In my opinion parents who now refuse to have their children immunised are putting the lives of those children at risk. In America, where measles immunisation is compulsory, measles, like smallpox, has been virtually wiped out. Here in Britain, because so many parents refuse, either out of obstinacy or ignorance or fear, to allow their children to be immunised, we still have a hundred thousand cases of measles every year.”

Much has been written about Dahl's dark side (e.g. "an equal-opportunity bigot"), but I give him credit for trying to help children and their parents avoid the misfortune he and his family experienced.

Published on Leave a comment on Measles in My Backyard

Well, not exactly, and directionally it's more like my front yard. On February 1 the Maryland Department of Health issued a press release of a measles case in a recent international traveler who resides in my Maryland county, listing an apartment complex with my same home zip code as a site of potential exposure. Details are lacking, and I do note the DOH still hasn't sent a notice to Maryland licensed physicians. Keeping my fingers crossed there are no secondary cases.

Last Summer's Vibrio vulnificus Flurry

CDC reported on last summer's burst of V. vulnificus infections across 3 states, a total of 11 severe cases occurring during heat waves in residents of Connecticut, New York, and North Carolina. Median age was 70, and 5 people died. Of the 10 with available information, all had at least 1 underlying risk factor for severe Vibrio infection, including diabetes (3), cancer (3), heart disease (3), history of alcoholism (3), and hematologic disease (2). While the clusters can't be blamed definitely on the heat, Vibrio growth is augmented in warm water; we may see an increase in Vibrio infections associated with climate change.

An impaired reticuloendothelial system (including liver disease from any cause) is a big risk factor; high risk individuals should be warned about avoiding contact with brackish water, salt water, and raw seafood (2 cases last summer had raw oysters as only known exposure).

Late Treatment for Congenital CMV

A new report from the Collaborative Antiviral Study Group reported on a phase 2 randomized, double-blind, placebo-controlled trial of 6 weeks of oral valganciclovir for infants 1 month to 3 years of age with congenital CMV infection and sensorineural hearing loss. Although the treatment group had much lower urine and salivary viral loads during treatment, there was no difference in hearing outcomes compared to the placebo group. Back to the drawing board.

Diphtheria in Africa

It looks like diphtheria is going to be a big problem for some time to come. WHO lists major diphtheria outbreaks in Nigeria (the most cases), Guinea, Niger, Mauritania, and South Africa. The cumulative total of suspected cases is 27,991 with 828 deaths. For those of you needing a little help with African geography, here's what it looks like:

So, this is not just clusters related geographically, but rather scattered throughout the continent. Cases were more prominent in the pediatric ages, and about a quarter of the cases were fully immunized. The numbers could be much higher given the difficulties in diagnosing diphtheria in resource-poor settings.

Bad E. coli in China

Although I'm never happy to hear about new virulent and resistant organisms, I was particularly unhappy about this news for a few reasons. First, it is a hypervirulent strain, apparently more likely to cause severe invasive infections. Second, it carries carbapenem resistance, often our last relatively safe resource in the antibiotic armamentarium for multiply resistant Gram negative bacteria. Worse is that 13% of these carbapenem-resistant organisms did not express a known carbapenem resistance gene, suggesting other perhaps new resistance mechanisms might be present. Lastly, these organisms caused a prolonged outbreak in a children's hospital.

You can see this outbreak occurred a few years ago, but I don't think we've heard the last of this.

WRIS

I'm looking forward to the week when I can retire a regular update on Winter Respiratory Infection Season. For now we have some encouragement but still too early to tell which way we're headed, especially with covid since our data sources are less reliable/predictive.

We seem to be over the hump with RSV season, still plenty out there but we tend not to see late rebounds with RSV.

Flu is a mixed bag depending on locale, but seems to be headed downward overall.

The covid wastewater report doesn't look too bad, either.

JN.1 is the predominant variant in most places now. I include a graph from the UK just because it's pretty.

We also have some other good news on the covid front: the fall vaccine seems to have high effectiveness (54%; 95% CI 46-60%) against development of symptomatic infection in immunocompetent adults. The study covered the time period September 2023 - January 2024 so is very recent and includes the time of JN.1 variant predominance.

Squirrel Wars 2.0

Speaking of my front yard, it is the new site of my war to keep squirrels away from my bird feeder, first mentioned in these pages on January 14. You recall that the capsaicin-laced safflower seeds, advertised as obnoxious to squirrels, turned out to be a delightful snack for those obnoxious rodents here. I tried to access research proven methods for preventing squirrels from eating all the bird food, but sadly there doesn't appear to be a trove of studies to guide me; in other words, no such thing as evidence-based squirrel medicine.

However, many sites mentioned trying to choose a site for a feeder that is beyond the reach of a typical squirrel's jumping prowess of 5 feet upward from the ground, 7 feet across, and 9 feet downward. After much thought, we selected a site in a large front yard tree. Armed with my long-suffering wife's long tree branch cutters and her assistance, 2 rickety ladders, slippery wire, packaging tape, and an autographed baseball from my youngest son's youth baseball team (circa 1990's, I was the official scorekeeper since I was too uncoordinated to be a coach), I succeeded in placing it in the perfect place with only minimal self-injury. Passersby seemed alternately amused and alarmed. If this works, I should get a MacArthur genius grant.

Published on Leave a comment on What About Me?

This week I realized covid shares a characteristic with my granddaughter. Sometimes, when she is the only child in a room full of adults taking about endless banalities, she interrupts us with a "What about me?" plea. Every week I gather potential topics for this blog from key medical journal email alerts, feeds from a few selected sources like CIDRAP, scanning the Washington Post, New York Times, and Wall Street Journal dailies, watching national news broadcasts when I can, and just generally keeping my eyes and ears open. I must see dozens of potential topics to include next week, and I bookmark a subset to reconsider at the end of the week.

This week I had a few more topics than usual, around 20, that I needed to winnow down. I quickly realized that all but 1 of them were related to covid. Try as I might to include topics on general infectious diseases, covid has succeeded in becoming the center of attention this week. I'll do my best to summarize a few of the pearls.

Covid Vaccine Updates

Pediatric healthcare providers can rejoice in some more good news: according to the AAP, Moderna has joined Pfizer in allowing free returns of unused covid vaccine doses, making it less financially risky for practices to order vaccine.

A few new studies confirm high vaccine effectiveness extending into the omicron era. First, a cohort study in 4 Nordic countries looked at mRNA covid vaccine effectiveness in adolescents completing 2 vaccine doses between approximately April 2021 and April 2023. A little over 500,000 subjects were included. Vaccine effectiveness against hospitalization was 72.6% (95% CI 62.5-82.7) with a suggestion that heterologous dosing (1 Pfizer dose and 1 Moderna dose) had slightly higher effectiveness at 86.0% (56.8-100). Similar numbers were seen when just the omicron time period was analyzed at follow-up periods of 6 and 12 months. It's important to note that hospitalizations were relatively rare, regardless of vaccine status, as expected in an adolescent population. (Norway isn't included below because too few hospitalizations occurred to allow for analysis.)

Another study looked at VE in US children (5-11 yo) and adolescents (12-20 yo), the latter group in both delta and omicron periods and the former group only during the omicron period (no vaccine was available for the younger group during the delta wave). It looked at a "real world" population, i.e. not part of a formal research study but rather examining vaccine usage as implemented after authorization/approval, using data available from 7 pediatric healthcare organizations. Again VE was high, For the Pfizer vaccine during the delta time period, VE against infection was 98.4% with narrow CI (those were the good-old days at least in this one feature, no covid vaccine has great VE against infection nowadays). During the early omicron period (up through November 2022), VE against infection was 74% in the younger children and 82% in the adolescents; durability of the protection was fairly stable over a 10-month follow-up period, although the CIs became very wide because so few events occurred.

Finally I'll mention a study in the "elderly" because it contains very recent data. In Denmark, VE reported as hazard ratios of the XBB variant-based vaccine (the one in use starting last fall) was highly effective against hospitalization in this older age group. Note the very short follow-up period, this information clearly is very preliminary and could change significantly as time passes.

Covid Epidemiology

The more interesting information about covid epidemiology this week comes from abroad. First, I loved this study from the UK because it used smartphone tracing technology, preserving confidentiality, to identify important determinants of covid transmission. A key finding was that the probability of person-to-person transmission increased with time, first linearly at 1.1% per hour of exposure but extending for several days. Household exposures were most likely to result in transmission. Distance played a role of course, but longer exposures at greater distances had about equal risk of transmission as shorter exposures at shorter distances. I could spend an entire blog post and more on this article. This information can provide excellent guidance for quarantining and distancing in the event of a large covid wave in the future. Remember that the original guidance earlier in the pandemic for distancing of 6 feet was mostly a best guess to prevent transmission, no great data to guide that advice.

A report from the UK government summarizes a wealth of data as the following (see page 3 of the pdf in the link):

"... COVID-19 Omicron variant cases were most infectious around symptom onset and up to 5 days after, but could potentially be infectious for longer, especially for cases that are hospitalised, immunocompromised, or otherwise high risk. Three studies looked at transmission before symptom onset. These suggested that between a third and a half of transmission events occurred before symptom onset in the index case. However, while some studies included substantial numbers of cases, most studies included relatively few cases, and the majority of studies included cases with Omicron variant BA.1 and BA.2, with only a small number of studies reporting evidence from 2023."

This information can help inform your discussions with all those parents who wonder about transmission to high risk family members and whether to risk exposure for a special event. If you want more data than you (or I) can handle about what's going on in the UK with covid, see this link. The Excel files are massive but very interesting for those of you who want to take a deep dive.

The final mention of epidemiology is a source for concern and caution. The Pan American Health Organization, PAHO, that is the branch of the WHO overseeing public health in the Americas, reported on respiratory illness activity in the southern hemisphere which is now in summer season. The key take-home point here is that, although North American is driving a lot of the SARS-CoV-2 positivity now, there is significant covid illness in Central and South America. This implies that covid is not quite a winter respiratory virus, at least not yet.

Covid Bottom Lines

As we enter our 4th year of covid, I realized I've learned a few key lessons to be applied for the future:

  • It's difficult to compare illness rates and other outcomes in the US over the years, primarily because we aren't collecting information in the same way as we did early in the pandemic. Wastewater data are mostly obtained as they were before, but this is at best a qualitative data source.
  • Covid vaccines are the most closely studied and monitored in history with now over 5 billion people worldwide receiving at least one dose. Every credible study/report has confirmed that, regardless of age or underlying risk factors, vaccinated individuals will have better outcomes than being unaccinated and infected, even after being infected multiple times. This takes into account all adverse events following vaccination itself. For virtually every individual, vaccination is the better choice. From a public health perspective, vaccination of some low risk groups may not be cost effective. This is why the UK, for example, does not provide vaccine for some healthy children; UK health authorities have decided the money is better spent on other aspects of health care.
  • Although there are similarities, SARS-CoV-2 is not just like influenza virus. The mutation rate is much higher, meaning that we still face a faster moving target for new vaccine and therapeutic drug development. Also, as mentioned above, seasonality isn't yet clear. So far SARS-CoV-2 isn't just a winter respiratory virus.
  • Even though the omicron era seems to have brought less disease severity, SARS-CoV-2 is still a major killer, now at a rate of about 1500 deaths per week.

Please encourage everyone to be up-to-date on covid and all other vaccines.

WRIS

Winter Respiratory Infection Season clearly is still with us. I await more data to see if the winter school break resulted in fewer, greater, or had no effect on WRIS infection numbers. However, I did notice a report from China that provided evidence that school breaks lessened influenza transmission during the years 2015-2018.

RSV-NET: CDC is still projecting a downturn nationally, but too early to be certain of this.

FluView still shows significant influenza-like illness activity, at least as of a week ago. It's definitely not too late to be vaccinated.

And ... More What About Me

It's my blog, what could be a more pitiful plea for attention? So, speaking of me, note that the CDC published the 2024 adult immunization guide that not only includes old codgers such as yours truly but also extends down to 19 years of age.

One last bit, an update to my bird feeder adventures I mentioned last week. I had a great few days of multiple bird species sightings, followed by a squirrel invasion - those dastardly rodents cleaned out the birdseed supply in a couple days. I've now been researching squirrel deterrents, being careful to not actually hurt them although I admit to having occasional sciuricidal thoughts. It looks like I'll be moving the feeder and engaging in some high-wire techniques to squirrel-proof the new location, hoping I don't end up with a spectacular ladder fall and resultant visit to my local ER.

Published on Leave a comment on Winter Distractions

My soon-to-be daughter-in-law recently gave me a bird feeder - not just any bird feeder, but a smart one that has a camera connected to my wifi that takes photos and videos of any birds that show up. I had my first visitors this morning, a few days after I stocked it with birdseed.

In the meantime, winter is here.

WRIS

A lot going on with our Winter Respiratory Infection Season, including some new items.

CDC issued new (or actually old) guidance for use of the long-acting monoclonal antibody nirsevimab for preventing RSV infection in young infants. The change was prompted by the announcement of greater availability of nirsevimab because the manufacturer released an additional 230,000 doses this month. Previously the guidance had indicated that the product should be prioritized for just a subset of infants at higher risk, but now recommendations are to go back to the original plan to administer to all infants less than 8 months of age as well as to infants 8-19 months of age with high risk conditions:

  • Children who have chronic lung disease of prematurity who required medical support (chronic corticosteroid therapy, diuretic therapy, or supplemental oxygen) any time during the 6-month period before the start of the second RSV season
  • Children with severe immunocompromise
  • Children with cystic fibrosis who have severe disease
  • American Indian and Alaska Native children

If supply is still limited in your particular area, then prioritization should be used as before. Still a bit vague but very important are all the nuances for ordering, administering, and being reimbursed for the product.

Along that same line, RSV may have peaked nationally.

Even with some good news about RSV slowing down, there's still plenty to go around. Also, influenza continues to drive a lot of healthcare usage for all ages around the country. Here is the percentage of emergency department visits due to the various respiratory infections:

Be aware that this site allows you to look just at your local jurisdiction - here is Maryland:

Covid

This week covid deserves a separate heading with a few new twists. Wastewater tracking once again has accurately predicted a surge in infections.

The JN.1 variant has increased rapidly and is projected to be the predominant covid strain in the US, but without any indication (yet) that it has increased virulence.

This might be a good time to review a bit about variants and also some recent covid findings. Variant nomenclature is confusing to me, I can only imagine how the general public sees this. Here is an evolutionary tree from the same CDC weblink as above.

The nomenclature is from the Pango system, but most people are more familiar with the WHO classification: the delta variant (remember those horrible days?) is B.1.617.2 near the left of the diagram. Omicron is represented in both BA.1 and BA.2. Now here's the important part when we consider new variants, immune-escape, and vaccines: JN.1 has developed on the BA.2 side, just like XBB but on a different branch of the tree. Remember that our current vaccines are based on XBB. As I've mentioned previously, XBB vaccine antibody seems to neutralize JN.1 pretty well in the test tube, but all vaccine (and natural infection) immunity declines significantly within a few months after vaccination or immunization. I would still expect the current vaccine to be pretty good for protecting against severe disease with JN.1 infection.

Although near and dear to my heart, I don't usually talk about old folks in this blog. However, a study of old folks in the Netherlands lends support to the idea that current vaccines are effective against new variants. Without going into details, you can see this study has very recent data and show excellent effectiveness for hospitalization and ICU admission for old folks. It's likely this benefit translates to the younger population that of course has lower rates of hospitalization overall.

Another recent study sheds some light on a question I've been wondering about for some time, namely how common asymptomatic covid infection might be in the omicron era. You might recall that one of the early surprises in 2020 was that asymptomatic infection was both common and very important for viral spread. That made the pandemic much more difficult to control. Now we have data from Hong Kong where rather unique epidemiologic circumstances prevailed. With a population of 7.5 million, Hong Kong officials had still had managed to prevent covid spread very effectively prior to the omicron era, with only about 0.5% of the population having been infected. That ended in early 2022, but it also offered researchers an opportunity to look at rates of asymptomatic infection during the omicron period because virtually none of the population had been infected previously. Using antibody testing, they estimated that 16% of the population was infected during the first 6 months of 2022 and that the percentage of asymptomatic cases was at least 42% (taken from those with reported SARS-CoV-2 infections) and possibly as high as 72% (looking at combined reported and unreported infections). Wow. That doesn't necessarily mean we would have those same rates of asymptomatic infection in the US where we've had a very different epidemiologic curve over the years, but I think it's likely we have a lot of asymptomatic covid surrounding us now.

Some good news about long covid, AKA PCC (post-COVID-19 condition) in children. This Canadian study looked at pediatric emergency department data and found that PCC was present in only 0.67% at the12-month follow-up periods in children testing positive for SARS-CoV-2. That's not the only good news part of this; the rate in a control group of children testing negative for covid was 0.16%, suggesting once again that other infections can trigger some of these long term symptoms. We have NIH-funded studies in the US ongoing now, with good control groups, that should go a long way in giving us guidance for managing PCC as well as other long-term conditions triggered by infections.

The Tipping Point

FDA officials, including Peter Marks who is the director of CBER, recently published a viewpoint article about a vaccination tipping point, i.e. the fact that vaccine hesitancy issues have resulted in a severe decrease in immunization coverage, opening us up to major outbreaks soon. I mention this both because it perfectly supports my views expressed in recent weeks but also it gives me a chance to give credit where credit is due. The term "tipping point," as applied here, often has been credited to Malcolm Gladwell. However, his popularization of the term in a sociologic context earlier this century should go to Morton Grodzins who first adapted this for use in explaining racial integration of neighborhoods in the middle of the 20th century. I'm hoping Gladwell credited him.

In Case You Missed These

Two other articles caught my eye this past week. First is a quality improvement article about shortening treatment duration for children with community acquired pneumonia and skin and soft tissue infections. If you're one of those practitioners who still treats these for 10 days (because we have 10 fingers), check it out.

Secondly, I was attracted to a report about variation in rates of how primary pediatric providers use pediatric subspecialty consultations. Although not the main focus of the report, I was most drawn to the mention that the top 2 conditions for using a pediatric infectious diseases specialist were positive tuberculin skin test and inactive tuberculosis. This jives with my personal experience and certainly points to opportunities to lessen use of subspecialty health care. Multiple resources exist for managing latent tuberculosis infection, including the AAP's Red Book, the CDC, and UCSF's Pediatric TB Resource Page.

For the Birds

My first video stars at the bird feeder were a white-breasted nuthatch, maybe a tufted titmouse (looks a lot like the nuthatch, I couldn't figure it out), and a house finch. When I received the bird feeder, I immediately wondered how best to avoid attracting squirrels and other rodents. I did a bit of web searching and then journeyed to my local bird authorities at the Woodend Nature Sanctuary who of course turned out to be the most helpful. I armed my feeder with capsaicin-treated safflower seeds, not a favorite of squirrels and the like, plus birds can't taste the hot pepper. So far the birds seem to like it.

As for me, it appears I've fallen down another rabbit hole, similar to my butterfly fascination. My wanderings have now included a look at how climate change is affecting our bird populations, as projected by the Audubon Society (apologies for using his name, now controversial, but the Society hasn't yet changed it) in their field guide.

Here is how things will change for the white-breasted nuthatch's winter range with a 1.5 C increase in temperature.

For the tufted titmouse

and the house finch

With more severe temperature increases, the ranges are altered more dramatically. I still hope for some action that will reverse these trends.

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