Developing Advanced Lab Tests to Inform Polio Eradication Strategy

Education

I grew up in Texas, was interested in biology by middle school, and thought I might want to be a park ranger. As I described in a polio eradication oral history video, I volunteered for a trail maintenance/park restoration program for high school students for two summers and found out that I didn’t want that lifestyle. I accepted a full-ride presidential scholarship to study biochemistry at Texas A&M University and graduated with a B.S., magna cum laude.   

In my senior year of college, I took the Medical College Admission Test (MCAT) but decided to pursue research instead of clinical medicine. I joined my future husband at the University of Utah in Salt Lake City, enrolling in its PhD program in cellular, viral and molecular biology. My dissertation was a mutational analysis of the poliovirus RNA polymerase, and I was awarded the PhD in 1991. Later that year, I moved to Seattle for a post-doctoral fellowship at the University of Washington where I conducted research on retroviruses. 

First CDC Job

My husband didn’t want to move east of the Mississippi but, towards the end of my post-doc, I saw an ad for a professional-level research microbiology position at CDC in the journal Science.  My husband saw the handwriting on the wall when I commented that the job description could have been written specifically for me, so I applied for the job through the federal process. It took several months for CDC to contact me, but then I was interviewed and offered the job. We moved to Atlanta and I started work in a CDC unit that focused on respiratory and enteric viruses and employed molecular virology techniques. With the exception of a few temporary assignments, I stayed there for my whole career. 

Later CDC jobs

Because my graduate work had been in polio, I became lead microbiologist and a lab team lead in 2006.

Final CDC job

A few years ago, I was promoted to an acting position in which I supervised 81 staff, including an epidemiology team and 6 lab teams. My position became permanent after 3 years, and I retired from it in the spring of 2025. 

Our division of labor was highly productive for both state-of-the art support of the global polio eradication effort and more basic research. For example, one lab team provided support for getting high-quality, up-to-date reagents (i.e., chemical and biological test components) out the door to the 131 country labs around the world that were accredited to use the real-time PCR test. That test detects poliovirus strains using the 2nd most advanced technology ever developed. It determines whether a strain is wild or vaccine-derived and whether it is Sabin serotype 1, 2 or 3, and that is the information needed to direct vaccination strategy in a specific geographic area. The same lab team was responsible for continual updating of the PCR assays (i.e., test “recipes”) to match the strains circulating in various parts of the world.

I’ve worked closely with the World Health Organization (WHO) Global Polio Laboratory Network from its inception until this year; the major support provided by CDC has been key in the elimination of wild poliovirus from all but two countries. The scientists who hired me had written the Network’s plan, and CDC funded the regional and global lab coordinators and still serves as a global specialized laboratory. My former unit also develops safe, easy-to-use methods for identifying polio strains and tracking their spread, and then transfers that technology to country labs around the world. 

Our lab scientists prepare and administer annual proficiency tests for the PCR and sequencing methods as part of an annual accreditation process; this quality assurance program allows us to trust results reported from country labs and identifies needs for technical assistance. The global network is composed of 144 labs, 6 of which function as global specialized labs.  CDC functioned as the lab of last resort for the world, with a highly trained staff 5-10 times larger than the other specialized labs, the greatest technical capacity, and the largest polio lab budget in the world.  Every year, our budget has been safeguarded by a polio eradication line item that our Rotary Club Foundation Network partner has lobbied Congress to keep.      

CDC hasn’t just transferred new techniques. We have coordinated with WHO on more in-depth training of polio lab staff, and even hosted visiting scholars from other countries when possible.  Several of these trainees have earned doctoral degrees and become the leaders of key regional labs. One aspect of the workload these labs shoulder is viral surveillance (i.e., testing for the virus itself rather than for an immune response). This involves genetic sequencing. In the past, our CDC unit performed sequencing for Nigeria because it’s such a large country and has had outbreaks of vaccine-derived polio (VDPV), but thanks to our technology transfer efforts, sequencing for most of Africa is conducted by the regional lab in South Africa. Regional labs in Pakistan, the Pan American Health Organization region and other parts of the world also do polio surveillance via sequencing.

Over time, the testing technology has shifted, advancing from more antigen-type tests to PCR tests and then to genetic sequencing. Our unit contributed a great deal to the shift in testing technology. The new approaches have delivered quicker strain identification, provided more specific information about where a given strain was circulating, and allowed immunization in the right places with the most appropriate vaccine. This level of precision can save scarce eradication resources. For example, we determined that cases identified in China were due to lab contamination, not community circulation, saving a million dollars on a vaccination campaign. 

The last cases of a disease are always the most challenging to eliminate, and the best technology possible is needed to make inroads into hard-to-reach reservoirs of the virus such as the mountainous, porous border region between Afghanistan and Pakistan. The biggest problem is that good immunization campaigns are hampered by civil unrest, cultural issues, and the lack of quality control infrastructure, but when virus circulates in a population, mutation becomes a concern that requires precise testing.

Sabin attenuated oral vaccine (OPV) requires only a 4 degree centigrade (refrigerator temperature) cold chain, while the injected Salk inactivated vaccine (IPV) requires a -30 degree centigrade (freezer temperature) cold chain. The more easily transported OPV in the vial works well in a place with good vaccine coverage. Vaccine-associated paralysis (VAPP) occurs in fewer than 1 in a million people who receive the original oral vaccine, and many countries accept that risk. Polio mutates as fast as any other virus at the nucleotide level but not at the surface protein level, so the vaccine still works even after a strain mutates. But where vaccination coverage is low, VAPP (polio derived from mutations of the live, attenuated virus) can be a real threat. Children who take the inexpensive, relative easy-to-transport, original oral vaccine excrete the virus, play with and expose other children, who in turn expose their own contacts, and so on. The chain of exposure offers the virus opportunities to mutate and recombine with other viruses, regaining paralysis potential. Even after mutation, only 2.1% of those infected get paralyzed, and a genetically stabilized, novel oral vaccine for type 2 polio (nOVP2) has been developed. Still, the risk of paralysis from mutated, circulating virus shows the need for stepped up research, surveillance and vaccine campaign efforts.

Stabilization research on other types of polio virus and on other viruses is underway in CDC labs, and we also assist in conducting seroprevalence surveys in specific countries to learn about susceptible populations. My work also contributed to a vaccine design strategy developed by a consortium funded by the Gates Foundation. It led to nOVP2 being rolled out by WHO, the first vaccine to be approved under the Emergency Use Listing. Two billion doses of the nOPV2 vaccine have been used, and we’re testing to make sure it’s behaving well as a vaccine. 

We collaborated with a global working group co-chair from WHO to move the new tech into practice. This was the new working group that created a sequence (nucleotide) database for polio, modeled after a similar one for measles and rubella. They will allow for more direct analysis, and I was able to push relevant publications forward. 

It should be noted that the unit I directed also performs surveillance work on other enteroviruses. For example, we were responsible for detecting and identifying viruses associated with acute flaccid myelitis (AFM) in the United States.

Activity with the Greatest Impact and Why

While wild polio was eliminated from all countries except for 2 before I was promoted to my final leadership role, I held that position during the covid pandemic. Some of the polio work paused while our resources and labs were applied to covid, and WHO told the African laboratories to do that too. Polio campaigns halted for a while, but we contributed capacity to detect covid. 

Proudest Achievement at CDC 

I am proud of helping to protect millions of children from the agony of polio paralysis. Specifically, leading the transfer of the testing tech, especially the sequencing tech, to the other labs. Many of the labs are now able to use molecular techniques, and we’re figuring out how to quickly sequence the whole poliovirus genome, an advance that will not only fine-tune the polio eradication effort, but also be a model for fighting other viral pathogens. 

With regard to my final leadership position, I’m proudest of leading the labs during covid.  We were protected a little because polio was classified as an emergency by both WHO and CDC, but of my staff, 5–10% did covid rotations. After such a long polio eradication push, we needed a little boost; the covid work gave it to us and we even grew a little.      

Leaving CDC   

My family had been trying to get me to retire, but I wanted to wait until polio was eradicated.  I came to realize that I wouldn’t see eradication, but the new administration accelerated my departure by several months. I put in my retirement papers following the conventional procedure early in the new administration because I didn’t really trust the deferred resignation DOGE option—so few answers were forthcoming. 

There is now a concerning shortage of CDC leaders who are experts in viral disease. Another supervisory scientist at my level retired the month after I did. The head of the epi team left to go to industry a few months ago, and there is a temporary replacement from another CDC unit.  My job was initially filled by my deputy (a senior administrative staff member) and then by one of the team leads on a temporary basis. Three staff members were laid off from the probationary roll (i.e., employees with less than 1–2 years in a job), including one Lab Leader fellow and two scientists who had just been hired in permanent (i.e., FTE) positions. We had finally gotten those FTEs after 6 years, and we got good, experienced people, one of whom came from the Veteran’s Administration. They were brought back 4 weeks after being fired but the group is uncertain about its future under the new budget, even though the Senate put polio funding back into the president’s budget. 

We thought we were going to have to cut 40% of our contractors, but another group at CDC took that hit instead. We had been restricted from talking to WHO or any outsiders, but that was changed by bringing this administration’s attention to a paralytic case in NY that was reported in the MMWR in 2022. It was an unvaccinated adult in a religious community that resisted vaccination. Our unit was able to work with the NY state lab which had adopted our sequencing over the years to track polio in sewage for several months. Luckily, it was the last case. 

I feel bad about the work disruptions and slander, although we weren’t hit as hard with disinformation as others were. Florida was still going to require polio and measles immunization after they cut vaccine mandates. 

People at the grass roots in the lab are still doing the work, they can talk to external colleagues, and they are continuing work on clinical trials and a limited amount of sequencing surveillance. However, these colleagues and friends worry that their work might not be valued and question whether they’ll be allowed to continue. I need to acknowledge the top CDC leaders who stepped down—the 3-D folks (Drs. Debra Houry, Demetre Daskalakis, and Daniel Jernigan) and Dr. Susan Monarez, the CDC director—that was such a hard decision, but it was necessary for their integrity. It’s hard to think about my colleagues doing all this challenging work when, without the leaders, they don’t know where it’s going. 

Future Plans

To protect the U.S., a lot of work should continue. I’m still involved in the polio work via temporary, voluntary adviserships through WHO, and I’ve attended a couple of meetings that required travel. I plan to stay on committees I’ve been involved in for years outside of my regular job. I’m on the Pakistan/Afghanistan advisory group. I also serve on a committee that looks at international health regulations designed to fight the spread of polio from country to country. For continuity, I’m part of a small working group on laboratory methods, emphasizing the nucleotide sequencing database I pioneered. And upon request, I answer questions from colleagues.

Other Comments  

I want to emphasize what the U.S. would lose if we couldn’t get surveillance information from WHO when polio hits. When there’s a paralysis case anywhere in the world, two stools must be taken and tested. There is also environmental testing (mainly of waste water) in areas at high risk for poliovirus. In order to continue to support global polio eradication, other network laboratories will have to take over the roles formerly played by the CDC laboratory, such as developing and distributing reagents for molecular tests (PCR and sequencing), and that will take time, which allows new challenges to arise.   

The loss of the WHO data would have a major impact on the U.S. too. Most people who have polio don’t know it. If, due to our lack of support for and contact with WHO, we don’t get information about polio circulation globally, we’ll have to do a great deal of surveillance here ourselves (e.g., wastewater testing) to identify risk in communities, and it will be very expensive. We were able to use some samples banked for covid in NY when the vaccine-derived case surfaced there, but substituting widespread testing here for strategic data collection in affected countries would be a lot of squeeze for a little bit of juice.