Outbreak, epidemic or pandemic risk

Diphtheria, though largely controlled in many regions thanks to vaccination, outbreaks are still reported today, especially in populations with low immunization coverage, high mobility, or poor living conditions.  Diphtheria outbreaks have been reported in various settings, including refugee camps in Asia, and among asylum seekers in Europe. ,  
Tetanus is generally rare in areas with high vaccination coverage, and since it is acquired from environmental sources, it does pose a risk for outbreaks. 
Pertussis has a well-documented history of causing outbreaks, even in populations with high vaccination coverage. Recent trends show that pertussis continues to have significant outbreak potential worldwide, affecting both children and adults, and posing particular risks to infants. ,  
Hepatitis B has significant potential for outbreaks, especially in settings with poor infection control or low vaccination coverage. Outbreaks of hepatitis B have been documented in both healthcare and community settings, and the virus remains a persistent public health threat in many regions. ,  
Prior to widespread vaccination, small outbreaks or clusters of cases of Hib disease have been noted in day-care centres and there were reports of nosocomial transmission in hospitals. The risk of Hib disease was also higher in larger families. 
The risk of poliovirus outbreaks and localised epidemics remains significant in areas with low vaccination coverage, fragile health systems, or gaps in immunization campaigns, particularly in regions experiencing conflict or displacement. Wild poliovirus (WPV) is endemic to Afghanistan and Pakistan, while vaccine-derived poliovirus (cVDPV) outbreaks have been reported in 20 countries in 2024. There is a rising risk of outbreaks of cVDPV2 since the global switch to bivalent oral poliovirus vaccine (bOPV). Although the global pandemic potential is low due to widespread immunity and effective vaccines, lapses in immunization and surveillance have led to the detection of poliovirus in environmental samples in previously polio-free countries. , , ,    

Sources

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