As we enter the fifth year of this challenging decade, life finally appears to be inching toward normal — a new normal — on the infectious diseases front.
Humans and the SARS-CoV-2 virus seem to be making progress toward a detente with each other. Covid is still a major disruptor, a significant cause of illness and death. But the massive disease waves of the early 2020s have calmed down. Masks, in the main, have disappeared. Holiday parties are back. Covid is falling out of the headlines.
But in the world of infectious diseases and global health, if it’s not one thing, it’s another. As we look to 2024, we can rest assured other issues will demand our attention. There surely will be stories that we cannot foresee — no one had global spread of mpox on their 2022 predictions list, for instance. But here are three health issues we’re pretty certain will bear paying attention to in the year ahead.
Will 2024 be the year the world finally stops polio transmission?
Most years since STAT launched in 2015 we’ve written a “3 to Watch” article predicting what’s to come in the infectious diseases and global health space. Nearly all of them have featured a “Will we? Won’t we?” section on polio eradication.
The job of wiping out paralyzing polioviruses, begun in 1988, was meant to be completed at the turn of the millennium. Several subsequent deadlines were set, including the latest, to stop circulation of all polioviruses by the end of 2023. They’ve all been missed and the 2023 deadline will be too.
But the Global Polio Eradication Initiative, a coalition of six organizations that lead the fight, now insists that 2024 will be the year transmission stops, and that the formal declaration that polio has been eradicated can be made in 2026, after two years without detected cases.
The numbers globally are low, but the challenges are mighty. Yes, there have only been 12 cases of wild polio reported in 2023. (That’s not the lowest number ever; there were a mere six cases in 2021.) Yes, two of the three types of wild polioviruses have already been eradicated, leaving only type 1 viruses circulating. Yes, wild polioviruses were reported in 2023 by only two countries. But those two countries are Afghanistan and Pakistan, where vaccinating all children has been a persistent challenge because of vaccine resistance and security concerns.
And then there’s the issue of vaccine-derived viruses, known in the polio world as VDPVs. Live, weakened viruses contained in vaccines used in some parts of the world — not the United States — can regain the power to paralyze if they have a chance to spread from child to child. In 2023, at least 411 children in 18 countries were paralyzed by vaccine viruses. That’s an improvement over 2022, when nearly 900 children in roughly two dozen countries were paralyzed by vaccine viruses. But getting to zero before the end of 2024 will be a daunting task.
And it will require substantial good luck, not something the polio program has ever had much of. An expert report assessing the status of the eradication effort that was released in the fall warned that the heavy focus on trying to stop spread of type 2 vaccine viruses in Africa was leading to under-vaccination of children against type 1 viruses, creating the possibility type 1 vaccine viruses could take off there.
We hope our “3 to Watch” report for 2025 notes that the clock has started to count down toward an eradication declaration in 2026. But with polio, you can take nothing for granted.
Whither pandemic preparedness and global health cooperation?
The World Health Organization has been hosting multinational negotiations on the creation of a pandemic treaty or accord aimed at helping the world respond better the next time a pandemic occurs. The goal is to agree to the wording of the treaty in time for the May 2024 meeting of the World Health Assembly, the annual meeting of the WHO’s governing body.
The purpose of the negotiations is to ensure a more equitable global response in the next pandemic, one that doesn’t see low- and middle-income countries forced to wait to get access to vaccines, drugs, and essential medical therapies when global supplies are tight. That’s a laudable goal, but one that will be very hard to deliver on.
Affluent countries that bought their way to the front of distribution lines during the Covid pandemic are not likely to sign agreements that hamstring them next time. Likewise countries with strong pharmaceutical industries are unlikely to agree to provisions that challenge the ability of those companies to hold intellectual property rights over vaccines and drugs.
Even if language that satisfies a majority of parties can be agreed to, it’s not clear if a country like the United States could sign on in the current political context, in which the Republicans hold the majority in the House of Representatives and the Democrats’ majority in the Senate is razor thin. Even though such an accord would not require countries to cede national authority and follow diktats of the WHO in a health emergency, it is already being framed as such in some quarters.
Hanging over all of this, of course, is the fact that 2024 is an election year in the U.S., one in which it remains quite conceivable that Donald Trump will win a second term. Trump signaled his intention to withdraw the United States from the WHO in the spring of 2020. His loss to Joe Biden later that year prevented him from formalizing the U.S. withdrawal. But there’s no reason to believe the heavy favorite for the Republican nomination has changed his views on the value of American involvement in international organizations like the WHO, leaving serious concerns about how lasting any U.S. commitment to a pandemic accord — if one is successfully negotiated — might be.
The impact of climate change on infectious diseases
As concern about Covid-19 began to wane, the media and at least some portion of the public reset their worry-o-meters to focus on climate change. With good reason — 2023 was declared the hottest year on record and climate disasters abound around the globe.
There are myriad health implications of a warming planet, but the one we’re thinking about here relates to the vector-borne infectious diseases — pathogens spread to people from insects like mosquitoes or ticks. “Our warming planet is expanding the range of mosquitoes, which carry dangerous pathogens like dengue, chikungunya, Zika and yellow fever into places that have never dealt with them before,” WHO Director General Tedros Adhanom Ghebreyesus warned during a press conference in the lead-up to COP28, the United Nations’ Climate Change Conference in Dubai that ran from Nov. 30 to Dec. 12.
Europe has already seen domestically acquired cases of dengue, in Italy, Spain, and even in the Paris region of France. In the United States so far in 2023, there have been 924 cases of domestically acquired dengue — though most (768) were recorded in Puerto Rico. California recorded two locally acquired dengue infections and Texas recorded one. The bulk of the mainland U.S. cases — 153 — occurred in Florida.
Assessing the risk posed by the climate-influenced expansion of range of the bugs that carry diseases — and therefore the diseases themselves — is a science that’s still evolving. (Read this terrific story in Science to get a sense of the current thinking.) But reports of locally acquired malaria cases in Florida, Texas, Arkansas, and Maryland — Maryland? — give people pause.
Watch this space.