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.