How might the potential resurgence of vaccine-preventable diseases affect global health security, economic stability, and societal resilience in the face of pandemics?
Routine immunization backsliding and the resulting resurgence of vaccine‑preventable diseases (VPDs) are already eroding three pillars that determine how the world weathers future pandemics: health system performance and formal preparedness, macroeconomic stability, and societal cohesion and trust.
Global routine coverage has stalled below the levels needed to keep high‑R₀ pathogens such as measles and pertussis in check.Immunization coverage - World Health Organization (WHO)who In 2024:
WHO and UNICEF estimate that 20.6 million children missed their routine first measles dose in 2024, up from 19.3 million in 2019.Immunization coverage - World Health Organization (WHO)who Zero‑dose children (no vaccines at all) increased from 12.9 million in 2019 to 14.3 million in 2024.Vaccination and Immunization Statistics - UNICEF DATAunicef These gaps are heavily concentrated in fragile and conflict‑affected settings, which now account for half of all unvaccinated children. Global childhood vaccination coverage holds steady, yet over 14 million infants remain unvaccinated – WHO, UNICEF who
Mathematically, herd immunity requires that the immune proportion pc exceed 1−1/R0 to keep the effective reproduction number Re=R0(1−p) below 1.Herd Immunitywikipedia +1 For measles and pertussis (R₀ ≈ 12–18), this yields critical coverage thresholds around 92–94%.Herd Immunitywikipedia Current global averages—let alone subnational pockets with far lower coverage—fall well short of this, guaranteeing recurrent and expanding outbreaks.
Measles is now functioning as a global “stress‑test” for health security. WHO, UNICEF and Gavi report:
In Africa, measles cases surged from 49,505 in 2017 to 416,957 in 2019, with deaths rising from 528 to 6,562; despite a temporary dip in 2020, cases rebounded to 141,789 and 1,460 deaths by August 2022, with 17 countries affected. Entangled epidemics: tackling vaccine-preventable diseases in the era of frequent epidemics in Africa - PMC nih In the Democratic Republic of Congo (DRC), nearly 300,000 measles cases and about 6,000 deaths in 2019 were reported—almost twice the number of Ebola deaths that year. Entangled epidemics: tackling vaccine-preventable diseases in the era of frequent epidemics in Africa - PMC nih +1
Recent modeling for the United States illustrates what sustained declines would mean in a high‑income setting. A 50% drop in routine childhood vaccination for measles, rubella, polio and diphtheria is projected to generate over 51.2 million measles cases, 10.3 million hospitalizations and 159,200 deaths over 25 years, with measles returning to endemicity within ~5 years in most simulations.Modeling Reemergence of Vaccine-Eliminated Infectious Diseases Under Declining Vaccination in the US - PubMednih The same study warns that measles may re‑establish endemic circulation even under current US coverage without improved vaccination and public health response.Modeling Reemergence of Vaccine-Eliminated Infectious Diseases Under Declining Vaccination in the US - PubMednih
Pertussis dynamics show the same pattern of temporary suppression during COVID‑19 followed by an “immunity gap” rebound:
Multiple countries are now reporting sharp post‑2023 rises:
In Europe, a continent that had largely eliminated diphtheria, an unprecedented outbreak linked to migration routes has unfolded:
Polio, once near eradication, has also re‑appeared:
Experience from Ebola and COVID‑19 shows that deferred routine immunization can produce “shadow epidemics” with death tolls comparable to or greater than the index outbreak:
A systematic review of Ebola‑era service disruptions found that presumptive tuberculosis cases dropped by nearly one‑fifth at the outbreak’s start, and smear‑positive proportions then rose—evidence that acute crises undermine care for other severe diseases. Impact of pandemics and disruptions to vaccination on infectious diseases epidemiology past and present - PMC nih
During COVID‑19, global modeling suggests measles vaccination disruptions could produce 0.24–1.16 excess measles deaths per 100,000 from 2020–2030 across several African and Asian countries, even without a concurrent novel pandemic. Impact of pandemics and disruptions to vaccination on infectious diseases epidemiology past and present - PMC nih These layers of risk make clear that letting VPDs resurge is not a manageable trade‑off but a compounding threat.
Every major VPD outbreak demands intensive case finding, contact tracing, isolation and surge clinical care, drawing on the same pools of staff, beds, diagnostics and funds needed for pandemic response.
A recent US modeling study of a 25‑year 50%‑coverage‑decline scenario across measles, rubella, polio and diphtheria projects:
Even localized measles outbreaks substantially distort capacity. The US CDC estimates each measles case requires labor‑intensive investigations and follow‑up; a 2018–2019 outbreak in Washington State (71 cases) cost about $3.14 million (US$47,479 per case), two‑thirds of which was public health response rather than clinical care.The Economic Impact of the Ongoing Measles Outbreak | International Vaccine Access Centerjhu +1 A broader systematic review of US measles outbreaks between 2000–2025 found:
These fixed and marginal costs translate into staff time, diverted surveillance, and postponed elective and chronic care. During COVID‑19, hospitals worldwide demonstrated how near‑capacity systems collapse under added demand: elective surgeries were canceled, ICUs overflowed, and emergency rooms boarded acutely ill patients.During the major COVID waves, hospitals across the country canceled elective surgeries, delayed cancer operations, postponed joint replacements, deferred cardiac procedures — because beds, ventilators, and staff were consumed by COVID admissions. I lived that. Many of us did. ICUs were full. Recovery rooms became ICU overflow. Surgical wards became COVID units. Now ask the obvious question: What emptied those hospitals? Not wishful thinking. Not podcasts. Not revisionist IFR math. Vaccination. After widespread vaccination, severe cases and ICU admissions dropped dramatically relative to prior waves — especially among the elderly and high-risk populations. The link between vaccination rates and reduced hospitalization was visible in real time across states and countries. Did therapeutics improve? Yes — steroids, anticoagulation, better protocols. Did the virus evolve? Yes. But the single largest shift in hospitalization risk curves followed vaccination rollout. If COVID had been trivial, we wouldn’t have shut down operating rooms. If it were harmless to the elderly, long-term care facilities wouldn’t have been devastated. Hospitals weren’t “emptied” by rhetoric. They were emptied by immunity — much of it vaccine-induced. You can debate policy. You can critique mistakes. But you cannot erase what frontline hospitals looked like before vaccines — and what they looked like after.x +2 Adding high‑burden VPD hospitalization waves—especially in pediatric and ICU beds—to that baseline makes it far harder to absorb shocks from a novel respiratory virus.
Queuing models from British Columbia show how resource competition plays out mathematically. A multi‑class Erlang loss model representing ventilator use by COVID‑19 and non‑COVID respiratory patients demonstrated that total access depends not only on epidemic case counts but also on background demand for pneumonia and ARDS cases, length of stay, and finite ventilator supply.A Queuing Model for Ventilator Capacity Management during the COVID-19 Pandemic | medRxivmedrxiv As the authors note, incorporating vaccination‑driven reductions in disease incidence into such models directly reduces critical care utilization, freeing surge capacity.A Queuing Model for Ventilator Capacity Management during the COVID-19 Pandemic | medRxivmedrxiv By symmetry, resurgence of VPD‑driven pneumonia (e.g., measles complications, pertussis) will raise baseline demand and erode that cushion.
Routine childhood vaccination has been repeatedly shown to generate large net savings. In the United States, the CDC estimates:
Recent estimates for US adult VPDs place the 2015 annual economic burden at roughly $9 billion, 80% borne by unvaccinated individuals. Modeling the economic burden of adult vaccine-preventable diseases in the United States - Johns Hopkins Universityjohnshopkins In LMICs, vaccinating against 10 key diseases between 2011–2020 in the 94 poorest countries is projected to avert US$586 billion in treatment costs, lost wages and productivity losses; 73 Gavi‑supported countries account for US$544 billion of those averted costs.Treatment of vaccine-preventable disease carries a heavy financial toll for national health systems – VoICEimmunizationevidence
UNICEF’s 2024 costing analysis finds that fully vaccinating a child under 24 months against 11 diseases in LMICs costs about US$73 on average (US$31 for vaccine and injection supplies plus US$42 delivery costs), with a range of US$46–US$130 per child.[PDF] Costs of Fully Vaccinating a Childunicef +1 Against per‑case outbreak costs in the tens of thousands of dollars in high‑income settings and household catastrophic costs of 10–83% of monthly income per illness episode in LMICs,Modeling The Economic Burden Of Adult Vaccine-Preventable Diseases In The United States | Health Affairshealthaffairs +1 investing in prevention remains economically dominant.
A new synthesis of US measles outbreak costs (18 states, 2000–2025) finds:
Scenario analysis for a hypothetical 1,500‑case US outbreak in 2025 projects:
A recent analysis of a real 2019 Clark County, Washington outbreak (71 cases) estimated overall societal costs of US$3.4 million—again about US$47,000 per case, two‑thirds borne by public health budgets.The Economic Impact of the Ongoing Measles Outbreak | International Vaccine Access Centerjhu
When caseloads climb into the tens of thousands globally, aggregate macroeconomic drag becomes significant. A Johns Hopkins commentary notes that more than 1,000 measles cases in the US in 2025 would impose “tens of millions of dollars” in societal costs, mostly falling on public health agencies and hospitals that divert personnel and resources from other priorities. The 2025 United States Measles Crisis: When Vaccine Hesitancy Meets Reality - PMC nih These budgets are not isolated from pandemic preparedness; funds spent chasing preventable outbreaks are unavailable for stockpiling critical supplies, training surge staff, or upgrading surveillance.
Vaccination supports economic stability not only through direct medical savings but by preserving workforce participation and educational attainment.
A concrete illustration comes from a 2025 measles outbreak in Texas:
The National Education Association warns that VPD‑related absences “often result in extended absences from school, jeopardizing students’ academic progress and increasing the likelihood of dropping out,” with disproportionate impact on low‑income children who lack resources to catch up.The Health and Economic Benefits of Vaccines | Johns Hopkins | Bloomberg School of Public Healthjhu Such shocks interact with already documented COVID‑era learning losses and chronic absenteeism, compounding human capital deficits.Big new annual report on kids shows "decades of lost progress" due learning loss during - and even after - Covid. Math & reading scores keep falling. Many kids just simply stopped going to school, with nearly 15 million "chronically absent" even post-Covid in 2022. This while tens of billions of the 2021 "reopen schools" money still hasn't been spent. Tough but necessary read. Keep in mind that no western nation kept kids out of school nearly as long as we did. Most not even close. Tough but necessary read. We owe so much to making it up to the kids. 2024 KIDS COUNT Data Book - The Annie E. Casey Foundation (https://t.co/Lmk18cvyNx)x
On the labor side, vaccine‑preventable adult illnesses generate absenteeism and presenteeism costs; for example, a US analysis of varicella found that universal childhood vaccination cut annual antiviral and antibiotic costs by US$181 million (≈95% reduction) relative to no vaccination, largely by preventing complications that drive care‑seeking and workforce disruption.Seasonal influenza: Knowledge, attitude and vaccine uptake among adults with chronic conditions in Italyplos +4 A separate modeling study estimated that adult VPDs related to 10 recommended vaccines imposed ≈US$9 billion in economic burden in 2015, mostly from unvaccinated individuals. Modeling the economic burden of adult vaccine-preventable diseases in the United States - Johns Hopkins Universityjohnshopkins
In LMICs, case studies compiled in a systematic review show that a single episode of pediatric pneumonia, meningitis, or acute gastroenteritis can cost households 1–75% of monthly income or 10–83% of monthly expenditures, driving debt and foregone investments in education or small businesses.Cost of Nine Pediatric Infectious Illnesses in Low- and Middle-Income Countries: A Systematic Review of Cost-of-Illness Studies.nih At scale, recurrent VPD outbreaks erode disposable income and domestic demand just as countries attempt to recover from pandemic‑related recessions.
Global health financing trends are moving in the wrong direction. In April 2025, WHO, UNICEF and Gavi warned that VPD outbreaks are increasing “amidst global funding cuts,” with nearly half of 108 surveyed low‑ and lower‑middle‑income countries reporting moderate to severe disruptions to vaccination campaigns and routine immunization due to reduced donor funding; disease surveillance was also impaired in more than half. Increases in vaccine-preventable disease outbreaks threaten years of progress, warn WHO, UNICEF, Gavi who
Gavi’s next 2026–2030 strategy is being set at about US$10 billion, with a confirmed ~30% cut in funding to WHO and UNICEF immunization activities and slower roll‑out of new schedules and campaigns, particularly in lower‑middle‑income countries.Gavi Cuts Staff And Support To WHO And UNICEF - Gives More Freedom To Countries To Decide Vaccine Priorities - Health Policy Watchhealthpolicy-watch Gavi and partners estimate that if the alliance is not fully funded for 2026–2030, “millions of children” will remain unvaccinated, increasing health security risks.World leaders recommit to immunisation amid global funding shortfallgavi
Analyses of hypothetical US funding cuts to Gavi suggest:
These same documents argue that weakened immunization systems also undermine cold chain, surveillance and workforce training, amplifying both VPD resurgence and the difficulty of mounting rapid pandemic responses. Increases in vaccine-preventable disease outbreaks threaten years of progress, warn WHO, UNICEF, Gavi who +1
From a macroeconomic perspective, this means LMICs must spend more on outbreak response and treatment per case while facing constrained budgets, reducing fiscal space to borrow or reallocate funds during pandemics. CDC notes that in LMICs each US$1 invested in immunization saves an estimated US$52, and fully upgrading routine immunization across low‑income countries costs just US$18 per child in vaccine procurement.Fast Facts on Global Immunization | Global Immunization | CDCcdc Choosing to absorb VPD outbreaks instead of financing immunization is therefore a deliberate acceptance of avoidable future macro‑shocks.
The Global Health Security Index (GHSI) directly incorporates measles vaccination coverage (MCV2) as an indicator in its “Prevention” category: countries scoring ≥95% MCV2 coverage receive top marks; 80–94.9% receive intermediate; <80% or no data are scored zero.GHS INDEX METHODOLOGYghsindex This formally recognizes routine immunization as a core pillar of epidemic prevention capacity.
However, empirical analyses of COVID‑19 outcomes reveal a more nuanced reality:
Most relevant to immunization, a 2023 study re‑computed GHSI scores after removing vaccination coverage components to avoid circularity, and showed that higher scores in the “prevention” and “rapid response” categories were the strongest predictors of preserving childhood immunization coverage from 2020–2022.Countries’ progress towards Global Health Security (GHS) increased health systems resilience during the Coronavirus Disease-19 (COVID-19) pandemic: A difference-in-difference study of 191 countries | PLOS Global Public Healthplos This suggests that systems with better baseline preparedness were more successful at preventing routine immunization collapse, thereby limiting future VPD resurgence even amid COVID‑19 shocks.The Global Health Security Index: Useful for guiding pandemic preparedness | PHCCphcc +1
Taken together, these results imply:
Multiple empirical studies now document “spillover” from COVID‑19 vaccine controversies to routine childhood vaccines:
Globally, a Nature Medicine perspective notes that COVID‑19 vaccine skepticism has extended to other vaccines, particularly routine childhood immunizations, with 23.1% of surveyed adults reporting they are now less likely to accept non‑COVID vaccines; the authors highlight this as a substantial threat to control of other VPDs.Influence of COVID-19 on trust in routine immunization, health information sources and pandemic preparedness in 23 countries in 2023 | Nature Medicinenature A separate survey of 23,000 adults in Asia found that 23.1% reported reduced willingness to accept vaccines for other diseases after the pandemic, and trust in physicians and WHO averaged below 7/10, underscoring a fragile information environment.Post-pandemic survey revealed the impact of trust crisis on routine ...dukekunshan
Cross‑national evidence shows that trust in government and public health institutions is a powerful predictor of compliance with pandemic measures:
A large global study of COVID‑19 outcomes found that higher interpersonal and governmental trust and lower corruption were associated with lower standardized infection rates and, in middle‑ and high‑income countries, with higher vaccine coverage and greater reductions in mobility (i.e., adherence to NPIs).Pandemic preparedness and COVID-19: an exploratory analysis of infection and fatality rates, and contextual factors associated with preparedness in 177 countries, from Jan 1, 2020, to Sept 30, 2021.nih The authors estimate that if all countries had trust levels similar to Denmark (75th percentile), global infections might have been 12.9% lower for government trust and 40.3% lower for interpersonal trust, if the associations were causal.Pandemic preparedness and COVID-19: an exploratory analysis of infection and fatality rates, and contextual factors associated with preparedness in 177 countries, from Jan 1, 2020, to Sept 30, 2021.nih
At the micro level, a longitudinal study at a large youth mass gathering found that baseline vaccine uptake predicted poorer adherence to physical distancing during the pandemic event, indicating that vaccination attitudes and NPI compliance are behaviorally linked rather than independent.Vaccine uptake and adherence to non-pharmaceutical interventions at a youth mass gathering event: A longitudinal field cohort study - ScienceDirectsciencedirect This suggests that communities drifting away from routine vaccines may also be less cooperative with future mask, distancing or quarantine measures.
Conversely, negative experiences with mandates can damage trust. An Australian federal COVID‑19 inquiry concluded that “mandating of public health restrictions, especially vaccination,” had the biggest negative impact on trust according to media summaries.BREAKING: Australia’s federal Covid Inquiry finds “the mandating of public health restrictions, especially vaccination, that had the biggest negative impact on trust.” https://t.co/7Te2AVNfTSx A Romanian study found that attitudes toward vaccination were significantly correlated with trust in government, president and parliament; lower trust was associated with higher hesitancy.Revisiting the Correlation Between Vaccine Acceptance and Trust in Hospitals: Lessons from the COVID-19 Pandemicmdpi
Thus, if VPD resurgence leads to more coercive policies and social conflict, a vicious cycle may emerge: declining trust → lower routine coverage → more outbreaks → harsher measures → further trust erosion, undermining future pandemic readiness.
VPD outbreaks and vaccination debates increasingly function as flashpoints in polarized societies.
Social network modeling shows how behavioral clustering of vaccine refusal turns high aggregate coverage into fragile protection. A simulation study found that when negative vaccination sentiment spreads via complex contagion (requiring social reinforcement), unvaccinated individuals tend to cluster tightly in social networks, sharply increasing both the size and frequency of outbreaks even when overall coverage appears sufficient for herd immunity.Complex social contagion makes networks more vulnerable ... - Naturenature The authors conclude that standard herd immunity thresholds can be “highly insufficient” if susceptibility is spatially and socially clustered.Complex social contagion makes networks more vulnerable ... - Naturenature
These dynamics have real‑world analogues: in US communities with high personal‑belief exemptions, measles outbreaks have occurred despite statewide coverage above 90%.Complex social contagion makes networks more vulnerable ... - Naturenature +1 The National Foundation for Infectious Diseases notes that misinformation linking vaccines to autism—despite repeated disproof—continues to fuel pockets of low coverage and outbreaks.Vaccines Save Lives: What Is Driving Vaccine-Preventable Disease Outbreaks? - NFIDnfid
Vaccine controversies also polarize broader political and social identities. Accounts from COVID‑19 highlight scapegoating of unvaccinated individuals, family and community fractures, and perceptions of mandates as political loyalty tests rather than neutral health measures.'Fox News Sunday' on August 15, 2021foxnews +1 Such divisions weaken the collective solidarity needed to sustain difficult but necessary measures in future crises.
VPD resurgence is not confined by borders. CDC emphasizes that “a disease threat anywhere is a threat everywhere,” and that outbreaks can disrupt societies and economies even if they never cross into a given country.Global Health Security | Global Health | CDCcdc Recent examples:
At the same time, immunization funding has become entangled with geopolitical and domestic politics. The US decision to withhold a US$1.2 billion pledge to Gavi, combined with dismantling of USAID and other donor cuts, has raised the risk that millions of children in low‑income countries will lose access to vaccines, undermining not just local health but global pandemic security.Vaccine-Preventable Disease: A Global Tracker | Think Global Healththinkglobalhealth WHO and UNICEF warn that if Gavi’s next strategic period is not fully funded, “years of progress” could be lost, with more outbreaks and higher treatment and outbreak‑response costs for countries already fiscally constrained.Increases in vaccine-preventable disease outbreaks threaten years of progress, warn WHO, UNICEF, Gaviunicef
Meanwhile, humanitarian crises and mass displacement complicate immunization and cross‑border surveillance. The ECDC diphtheria outbreak investigation emphasizes that C. diphtheriae spread along migration routes, and that failing to ensure vaccination and clinical access for migrants and homeless populations allowed sustained circulation and spillover into host communities.Diphtheria strain involved in outbreaks among vulnerable populations across Europe between 2022 and 2025europa Similar concerns apply to polio outbreaks in Papua New Guinea and elsewhere, which now require integrated campaigns across borders with strong community engagement.At the signing ceremony, Ambassador Mochizuki of @JapanEmbPNG reaffirmed Japan’s commitment to supporting PNG’s health security. Acting WHO PNG Representative Dr Tiko Josaia emphasized that this partnership bridges scientific evidence with real impact in communities. PNG Minister for Health, the Hon. Elias Kapavore, expressed gratitude for Japan’s enduring friendship and reaffirmed his Government’s commitment to managing this support with transparency and integrity. @WHO, Japan, and Papua New Guinea – a WHO Western Pacific Member State - are working together to secure a polio-free future — delivering protection to every child, one vaccine at a time.x +1
In regions such as MENA and East Africa, experts stress that effective cross‑border surveillance and decentralized implementation of International Health Regulations are essential for monitoring mobile populations and mitigating VPD and pandemic risks.UCSF Experts Explore the Crucial Role of Cross-Border Surveillance in Pandemic Preparedness | UCSF Institute for Global Health Sciencesucsf Comparing border closures to binational collaboration along the US–Mexico border, they argue that trust‑based cross‑border data sharing is more effective for managing shared threats.UCSF Experts Explore the Crucial Role of Cross-Border Surveillance in Pandemic Preparedness | UCSF Institute for Global Health Sciencesucsf
Recognizing that traditional injectable, cold‑chain‑dependent vaccines are logistically complex, especially in fragile settings, a wave of innovation aims to restore and extend coverage:
From an economic and health security standpoint, these technologies matter because they target the very constraints—cold chain, trained staff, outreach to remote and fragile communities—that now generate zero‑dose children and pockets of susceptibility. If scaled with appropriate financing and community engagement, they could:
However, the same reviews caution that without addressing trust, funding and health‑system capacity, delivery innovations alone will not reverse hesitancy or polarization.Essential childhood immunization in 43 low- and middle-income countries: Analysis of spatial trends and socioeconomic inequalities in vaccine coverageplos +1
Bringing these strands together, the resurgence of vaccine‑preventable diseases threatens:
Health security and preparedness
Economic stability
Societal resilience
In practical terms, high and equitable routine immunization is not only a child‑survival intervention; it is a central determinant of whether countries approach the next pandemic with:
Failing to restore and strengthen immunization now effectively trades modest, predictable investments (≈US$73 per fully vaccinated child in LMICs, benefit‑cost ratios >10:1) for a future of overlapping epidemics, recurrent macro‑shocks, and fraying social fabric.Health and Economic Benefits of Routine Childhood Immunizations in the Era of the Vaccines for Children Program — United States, 1994–2023 | MMWRcdc +2
From a global health security perspective, containing VPD resurgence—by closing coverage gaps, stabilizing financing, deploying delivery innovations, and rebuilding trust—should therefore be treated as a foundational pandemic‑preparedness investment, on par with surveillance, laboratories and emergency stockpiles.