whooping cough – Pediatric Infection Connection

Summer is (Un)officially Here

Bud WiedermannJune 8, 2025June 8, 2025Leave a comment

Yes, I know summer solstice is the official start of summer on June 20, but my self-centered slant counts the start of summer as when I finally break down and turn on my home air conditioning. That happened a few days ago when temperature hit the upper 80s, accompanied by high humidity.

Thankfully we survived another week with no major outbreaks, but a few things are smoldering.

GAO Report on Pandemic Preparedness

After every outbreak and pandemic, you can count on 2 things: finger-pointing and advice on preparedness to prevent past mistakes. Typically all is forgotten/unimplemented once the brouhaha calms and we all settle into our latest favorite TV shows or podcasts. Thus, we remain poorly prepared for the next challenge.

The Government Accounting Office convened an expert panel over 3 days in January, 2024, to develop recommendations for a coordinated national approach to diagnostic testing for pandemic pathogens. The report finally was released this past week with recommendations for the HHS Secretary.

Their Table 1 documenting 2 recent episodes involving diagnostic testing reminded me of its significant impact on my ability to provide high level service to my patients.

The GAO recommendations are sort of mom and apple pie stuff, very logical and thoughtful. I don't have high hopes it will go anywhere.

MIS-C Neurologic and Psychological Outcomes

A new study documented 2-year neurologic and psychologic outcomes of 95 children 5-20 years of age hospitalized with MIS-C between August 1, 2020, and August 31, 2021, at multiple sites in the US and Canada. A strength of the study was its longitudinal cohort design and use of sibling and community control children when available. The results were encouraging; although MIS-C children had more symptoms initially, by the 2-year follow-up the patients and controls were pretty similar. The article has a ton of data, please go to the source link for more details, but here's a quick snapshot of part of the results (note that higher numbers on the y-axis are worse outcomes for this particular test):

This is a relatively small but careful study that likely is valid for most MIS-C children, though please remember that young infants were not included.

Pertussis in the Americas

Whooping cough is definitely in the news, and on May 31 the Pan American Health Organization published an alert. I missed it that day, otherwise I would have included it last week. It provided numbers to back up what we already know, that pertussis is on the increase across the Americas. What I found most helpful were comparisons to pre-pandemic times because we all know that every infectious disease seems to be increased compared to the pandemic years. The figure below, adapted from WHO data, shows that in 2023 we had returned to pre-pandemic levels globally but did not see much rise in the Americas.

2025 vaccination coverage with 3 doses of DTP in the US isn't as bad as you might expect, though you can see in the footnote we have no data from the most recent 2 years.

In 2024 and 2025 the US is clearly back to pre-pandemic numbers of cases which usually are at least 10,000 annually. Washington, Oregon, and California have the most cases so far this year, and we've had 4 deaths nationally. It seems like 2025 will be more severe year for pertussis.

Clinician Attitudes Towards Earlier HPV Vaccination

You might recall I mentioned in my April 20 post about the ACIP meeting that there was controversy about making a recommendation to promote earlier administration of HPV vaccine at age 9-10 years; this is of course acceptable under current guidelines, but there was some pushback from some ACIP attendees that lumping the 9-10 age group with 11-12-year-old children for HPV vaccine would disrupt the the adolescent primary care visit schedule, plus would be less acceptable to parents.

Now comes a new survey of general pediatric healthcare providers and staff on HPV timing. It included 33 general pediatric practices in California and Colorado and was carried out between November, 2021, and April, 2022. It also included interviews with a subset of clinicians and office staff. A key point is that these practices were part of a study to implement earlier initiation of HPV vaccination; so, these study participants had actually gone through a change in HPV administration in their practices. This fact is helpful to provide real world evidence, but also is a potential source of bias.

It's hard to summarize everything from this report that included narrative statements by the providers and staff, but here's part of the results.

As you can see, the bulk of the respondents did not perceive a change in these parameters after switching to earlier HPV vaccination. I'm hoping this study will be included in any HPV vaccine discussion at ACIP later this month, but clearly this is a narrow sampling that may not apply to other practice settings.

Can't Get Away From Measles

This year's outbreak keeps percolating along without new major hot spots, but a couple of issues merit mention.

First, a brief research letter gives us some information about county-level, rather than state-level, MMR vaccine coverage. The US outbreaks in past years have pretty much been centered around unvaccinated pockets of children, such as a geographically defined religious community in New York City in 2019 and the Texas outbreak this year in another vaccine-averse, relatively isolated religious community. These examples just point out that it's the small pockets of extremely low MMR vaccine coverage that can trigger major outbreaks; knowing the percentage of children who have received 2 doses of MMR vaccine in a state doesn't accurately account for smaller, under-immunized, communities.

The investigators collected county-level data from state health department websites and compared pre- (2017-2018) to post- (2023-2024) pandemic coverage with 2 doses of MMR vaccine. Of course by using state data they encountered different methods for data collection and reporting, so it's a bit of apples and oranges. Furthermore, 13 states aren't included in any of the analyses for a variety of reasons: "Alaska, Arkansas, Delaware, Idaho, Mississippi, Nebraska, New Hampshire, Ohio, and West Virginia are excluded because they do not report county level vaccination data. Georgia, Indiana and Montana are excluded because they only report 1-dose MMR vaccination rates for children aged 19-35 months, which does not align with our focus on 2-dose MMR rates in this analysis. Illinois was excluded because it reports a compliance rate spanning preschool through grade 12, and preschoolers are considered compliant with only 1-dose MMR administered." Here's what's left for the report.

Don't be confused by lighter color shades. The states entirely gray are those with no data; the counties in white are those with the lowest vaccination coverage. I'll be interested to look at this map when our next measles hot spot appears.

The second measles twist concerns congenital measles. Yes, it is possible for a mother with acute measles to pass rubeola virus to the baby prior to delivery. I was reminded about this when I saw a sad statement from the Canadian Chief Medical Officer of Health about the death of a newborn probably due to congenital measles. Remember, Canada is having an even tougher year with measles than we are in the US.

The CMO of Health did not provide much detail about the child, reportedly due to privacy concerns. Congenital rubeola is one of the few measles features I've never seen personally. If you want to learn more, I found an open access case report.

Summer Reading

To put off some chores I need to do, I decided to count up the number of books stacked in my "to be read" pile; I'm up to 52 after a recent buying flurry. I think my stack has ranged from 20 to 80 most of the time. I just finished Philip K. Dick's Martian Time-Slip, a fun book for those who can tolerate his perspectives on life and reality. Psychiatrists in particular would love this one. Now I've started John Banville's The Lock-Up. He's a difficult author for me to read because he writes such beautiful sentences I can't skim over anything for fear of missing out on another perfect rendering of the English language. It's a short book that likely will take me as long to get through as one twice its length.

Fact or Fiction?

Bud WiedermannApril 27, 2025April 27, 2025Leave a comment

As I've detailed in many previous posts, the information stream that helps all of us understand what's going on in infectious diseases has changed. This started well before any US political changes, but the covid pandemic hastened the process. Some states declined to collect data such as wastewater pathogen tracking, and many lacked resources for case tracing and providing preventive measures. In 2020 the surrounding chaos, uncertainty, and a mixed bag of leadership messages weakened the public's trust of agencies such as CDC, FDA, NIH, and other governmental entities; vaccine hesitancy and refusal, already a significant problem, increased.

The past few months has seen significant cuts in public health infrastructure. Except for giving us number counts, CDC has been relatively silent in guiding us through the measles epidemic. I've found myself wondering whether the data sources I've relied upon in the past will be useful. Will my posts inadvertently contain more fiction than facts? Should I even continue this blog in the face of these changes?

I'll certainly keep trying, and I'll always point out any reservations I have about lack of source transparency and data limitations. More importantly, the threats to our old standby resources may give rise to new, non-governmental approaches to assuring good data and advice to the public. More on that after some updates.

Ebola in Uganda Has Ended

Here's something that really cheered me up. WHO reports that the Ebola disease outbreak in Uganda, caused by the Sudan virus subtype, is over. It started last January and eventually sickened 14 people (12 confirmed so far) with 4 deaths (2 confirmed, 2 probable). The last patient was discharged on March 14, starting the clock to watch for new cases. It is standard to watch through 2 incubation periods (21 days for Ebola) and, if no new cases occur during those 42 days, the outbreak is declared ended. This happened last week. It is a credit to the WHO and the Uganda Ministry of Health that it was contained so quickly. Implementing sound public health measures works.

So Much for Safer Poultry

Last August the US Department of Agriculture embarked on a plan to lower the amount of Salmonella acceptable in poultry products sold to the public in an attempt to curb a major cause of foodborne Salmonella outbreaks. As of April 25, you can kiss it goodbye, another casualty of politics.

Safety of Nasal Flu Vaccine in Asthma

Last week I touched on the ACIP discussion for allowing home administration of live attenuated influenza vaccine (LAIV). Although still a lot of details to be worked out, the data suggested that this could be feasible. But, what about children with a history of asthma or recurrent wheezing illness for whom LAIV is either contraindicated (ages 2 - 4 years) or precautionary/deferred (> 5 years)? It could be a bit tougher to avoid use of LAIV in this population if home administration is offered. Now we have results of a systematic review that, while far from definitive, suggest LAIV is safe in these children.

The researchers included a broad age range of 2-49 years. The 15 studies forming the core of the review were judged too heterogeneous to perform a meta-analysis, so I can't show you a nice forest plot that summarized the findings. However, the bottom line certainly suggested that LAIV has a similar safety pattern in people with asthma or recurrent wheezing, compared to those side effects observed in recipients of the inactivated injectable flu vaccine. I'm sure ACIP will be including this information in future deliberations.

What's With Whooping Cough?

You may have noticed new stories about whooping cough in the news. You also may have noticed I've been pretty silent about this so far, but now I think there is enough data out there to make some comments.

First, let's take a look at the past hundred years of pertussis in the US.

A few notables in the graph above. First, the introduction of DTP vaccine mid-20th century had a huge impact on pertussis, bringing cases down to modern day levels by 1970. Second, in the blow-up insert graph, you'll see a significant increase in cases in the early 2000's. This was mostly due to a change in diagnostic testing rather than any true change in disease incidence. PCR testing for pertussis became widely available during this time, replacing the insensitive and relatively labor intensive culture methodology. All of sudden we were confirming more cases because testing was easier, more widely available, and more sensitive.

The next big impact resulted from introduction of the acellular pertussis vaccine, designed to lessen the uncommon side effects of the whole cell vaccine including seizures (1 per 1750 doses of whole cell vaccine), hypotonic-hyporesponsive episodes (1 in 1750 doses), temperature above 40.5 C (3 in 1000 doses), and prolonged crying (1 in 100 doses). None of these events seemed to be associated with any long-term sequelae but still were scary, unpleasant, and very disruptive. All are rare with the acellular vaccines, which is great, but an unexpected outcome of the switch to acellular vaccines was waning immunity in school-aged children; this is manifested by the uptick in cases later this century.

A final note on the graph above is its sawtooth nature. Pertussis has been and still is an endemic disease that occurs in cycles every 3-5 years, likely driven by accumulation of non-immune hosts during these intervals.

So, with a surge in pertussis in 2025, how do we distinguish among the various causes? What are the relative contributions of a catch-up period following the pandemic when social distancing, masking, etc, limited pertussis infections, lower vaccination rates, change to a more sensitive case definition in 2020, and perhaps some of the regular periodicity of the disease? I don't know a good way to sort that out, although we may be able to make a good guess in hindsight a few years from now.

Here's what we do know about recent pertussis activity. First, 2023 saw a significant jump in cases, more than double the 2022 number.

Vaccination rates of infected children were very low, compared to the general population which was around 95% vaccinated.

In 2024 provisional data, we saw an even greater increase to 35,000 cases.

Note the very large numbers in the older children and adolescents who probably missed boosters during the pandemic.

So far in 2025 we have over 8000 pertussis cases in the US, on a schedule to exceed the 2024 numbers. If we don't improve immunization rates, we'll be back to the bad old days for pertussis in the US.

Measles

I can only dream of a time when I won't have a routine weekly measles update. Last week saw another 80 or so cases added to the tally now at 884 cases in 30 jurisdictions.

We are on track to exceed the 2019 totals fueled by the New York City-centered outbreak.

Also, check out last week's MMWR more detailed summary of measles for this year through April 17.

Science Fiction

I felt like I was reading another sci-fi apocalyptic novel rather than an article in a scientific journal. Modeling studies always need to be taken with a grain of salt, but this latest one is just plain scary. Investigators at Stanford did a pretty careful modeling look at what might happen with vaccine-preventable diseases in the US 25 years from now, based on varying vaccination level assumptions.

It took me a bit to acclimate to these graphs. First, note the y axis is on a log scale, so small distances are actually very large. Second, the left-hand sides of each graph depict lower rates of vaccination than we now have, while the right-hand sides are for higher coverage. Third, these are cumulative cases, not annual cases.

Chances are I won't be around in 2050 to know how accurate these models were, but my children and grandchildren likely will be. I'm hoping cooler heads will prevail and we'll see a tip towards the right side of the graphs well before then.

CIDRAP to the Rescue?

The University of Minnesota's Center for Infectious Disease Research and Policy has long been one of my go-to resources for updates. Now they have announced the formation of a Vaccine Integrity Project. Public health professional and CIDRAP director Dr. Michael Osterholm explained it this way: "This project acknowledges the unfortunate reality that the system that we’ve relied on to make vaccine recommendations and to review safety and effectiveness data faces threats. It is prudent to evaluate whether independent activities may be needed to stand in its place and how non-governmental groups might operate to continue to provide science-based information to the American public."

In other words, it is intended to be able to step in if FDA and ACIP cannot provide reliable vaccine guidance. It will start with an 8-member steering committee; the members weren't named except for the 2 co-chairs who are heavy hitters: Dr. Margaret Hamburg and Dr. Harvey Fineberg. The committee will start work by conducting information gathering sessions with a variety of experts and stakeholders. Future activities will depend on those results but could include providing independent panels to identify knowledge gaps or make recommendations for vaccine use and public policy. I look forward to hearing more about this.

See you on May the 4th.

Tag: whooping cough