The US Centers for Disease Control and Prevention (CDC) has expanded its Global Polio Alert, issuing Level 2 “Practice Enhanced Precautions” travel notices for five widely visited European countries after environmental surveillance found poliovirus in wastewater. The move does not close borders but urges travellers and health systems to check and update polio vaccination before travel, and highlights how wastewater surveillance is revealing silent spread of vaccine-derived polioviruses in places previously thought low-risk (CDC Travel Health Notices).
Polio is a highly infectious viral disease that can cause permanent paralysis and, in some cases, death. The recent detections are predominantly circulating vaccine-derived poliovirus type 2 (cVDPV2) identified through environmental sampling in metropolitan wastewater systems. Public health agencies in affected countries are responding with targeted vaccination and intensified surveillance to prevent local transmission and paralytic cases. The CDC’s advisory aims to reduce the chance of travellers acquiring or exporting poliovirus and to remind clinicians and immunisation programmes to close immunity gaps (MMWR report on European detections).
The development matters to Thai readers for two reasons. First, many Thais travel to Europe for work, study and tourism; an updated travel advisory affects pre-travel medical checks and vaccine planning. Second, the detections underline a global reality: polio can reappear via importation or vaccine-derived strains even in regions with strong health systems if pockets of under-immunised people exist. Thailand’s routine immunisation performance will determine how well it would resist any imported poliovirus, so the notice is a prompt for public-health vigilance and community-level action (WHO IHR Emergency Committee statement July 2025).
Key facts and timeline are straightforward. Wastewater sampling first flagged related vaccine-derived polioviruses in Spain in September 2024, with subsequent detections in Poland, Germany, the United Kingdom and Finland during late 2024 and early 2025. Genetic analysis shows these isolates form a related lineage linked to a known cVDPV2 emergence that originated in West Africa in 2020. Importantly, as of the most recent reports, no paralytic polio cases have been confirmed in connection with these environmental detections in Europe, suggesting limited or no sustained person-to-person transmission so far. Nevertheless, the genetic divergence of the viruses indicates they circulated undetected for months before being found in wastewater, demonstrating the value of environmental surveillance as an early warning tool (CDC MMWR notes on European detections).
Public health bodies have moved quickly. A WHO Emergency Committee concluded in July that the global polio situation remains a Public Health Emergency of International Concern (PHEIC) and extended temporary recommendations to reduce international spread. Those recommendations include intensified surveillance, closing immunity gaps through vaccination (including providing IPV to travellers from infected areas under certain circumstances), and, where appropriate, issuing vaccination documentation for cross-border travellers from countries actively infected with polio strains. The committee warned that cVDPV2 outbreaks are driven by gaps in routine immunisation, displacement and insecurity, and that continued international coordination and funding are essential to prevent further spread (WHO IHR Emergency Committee statement).
Experts and public-health authorities stress measured action rather than alarm. The CDC’s Level 2 travel notice—“Practice Enhanced Precautions”—means travellers should ensure they are up to date on polio vaccination and take routine hygiene precautions. The CDC advises that adults who completed a polio vaccine series as children but who will be travelling to an area with circulating poliovirus and who have not previously received an adult booster should consider receiving one dose of inactivated polio vaccine (IPV) before travel; persons who received a full IPV schedule as adults do not routinely need additional doses unless immunocompromised or otherwise advised by clinicians (CDC Travel Health Notices). WHO experts emphasise that high routine immunisation coverage and sensitive surveillance are the pillars that prevent importation from taking hold and causing paralytic disease (WHO polio recommendations and context).
For Thailand the implications are practical and immediate. Thailand has maintained high immunisation coverage for childhood vaccines in recent years, with WHO/UNICEF estimates showing strong pol3/IPV historic coverage relative to some regions, but gaps can exist in marginalised communities and among mobile populations. Routine immunisation, including a timely second dose of IPV where used, remains essential to prevent vulnerability to importations. Thai health authorities should reinforce routine immunisation checks at school and community clinics, maintain acute flaccid paralysis (AFP) surveillance sensitivity, and consider targeted communication to groups who travel frequently to Europe—students, migrant labourers, business travellers and tourists—about pre-travel vaccination and documentation (WHO Thailand immunization profile).
Historically, Southeast Asia has shown how concentrated vaccination campaigns can close gaps: the WHO South-East Asia Region was certified polio-free for wild poliovirus in 2014 after aggressive routine and campaign immunisation. That success underscores two Thai cultural assets that help in a polio response: strong family responsibility for child health and respect for official health guidance. These cultural values can support high uptake of catch-up or booster campaigns if they are needed. Yet Thai authorities also know from experience that rural, undocumented or mobile populations can be missed by routine services; reaching those groups requires mobile teams, flexible hours, and community engagement through trusted local leaders and Buddhist temples that often serve as community hubs.
Looking ahead, several scenarios are plausible. If routine immunity remains high and environmental detections remain limited to wastewater without clinical cases, the risk to Thailand will be low and the situation manageable with targeted advice for travellers. If surveillance reveals increasing environmental detections or rare paralytic cases in Europe or elsewhere, WHO and national programmes may call for more assertive responses, including intensified vaccination drives or targeted booster doses for high-risk travellers. Global funding shortfalls for polio eradication could complicate rapid responses in lower-income or conflict-affected countries, increasing the risk of further spread; WHO’s emergency committee has flagged fiscal gaps as a significant threat to eradication goals and urged donors to fill shortfalls (WHO IHR Emergency Committee statement).
For Thai clinicians, public-health officials and travellers, the practical steps are clear and feasible. Travellers planning visits to the named European countries should check their vaccination history with a clinician at least four to six weeks before departure; adults who are unsure about a complete polio vaccine series should receive a single IPV booster as recommended for travellers to areas with circulating polio. Health facilities should maintain up-to-date records and be prepared to issue vaccination documentation if required. Public-health units should review AFP surveillance performance indicators and consider expanding environmental surveillance in large international airports or port cities if epidemiologically justified. Schools and childcare centres should verify that children are current with routine immunisations and facilitate catch-up doses where necessary (CDC travel advice and WHO recommendations).
In practical terms for Thailand’s health system, this means three targeted actions: first, re-affirming routine immunisation by ensuring all infants receive the scheduled IPV-containing doses on time and promoting the second IPV where applicable; second, strengthening surveillance—encouraging prompt reporting of any AFP case and evaluating whether environmental surveillance pilots are appropriate in Bangkok or other international hubs; third, issuing clear, culturally-tailored travel health guidance through hospitals, travel clinics, and embassies that explains why a booster may be recommended and how to obtain it. Community engagement should lean on trusted networks—primary care units, temple-based health volunteers and school nurses—to reach families that might otherwise miss vaccination notices.
The CDC’s notice and WHO’s PHEIC status are reminders that polio eradication remains an unfinished global public-health mission. Thailand’s previous successes and current infrastructure position it well to prevent local impact, but vigilance earns continued protection. Families planning travel should treat polio immunisation like any other routine travel vaccine: check early, vaccinate if needed, and keep documentation. Health officials should use this moment to close any remaining immunity gaps, particularly among mobile and hard-to-reach populations, reinforcing a core public-health truth: until polio is eradicated everywhere, it is a threat everywhere (CDC Travel Health Notices; WHO IHR Emergency Committee statement; MMWR report on European wastewater detections).