Climate change can impact vaccine efficacy, safety and access: Study

Extreme temperatures, humidity, flooding, and droughts are some of the climate change-related factors that might alter pathogens, jeopardise vaccine storage and delivery, and impact immune responses

Climate change threatens global health by changing environmental conditions and affecting the efficacy of vaccines, a new study found. Although the effects of climate change on infectious diseases are well established, the study examined the effects of climate change on vaccine reactions, including efficacy, safety, and equity.  

The study found that extreme temperatures, humidity, flooding, and droughts are some of the climate change-related factors that might alter pathogens, jeopardise vaccine storage and delivery, and impact immune responses. 

These factors compromise vaccine efficacy and safety, particularly in marginalised populations, and impact vaccine stability and host responses, leading to negative health outcomes. Therefore, climate change can worsen vaccine disparity by reducing favourable immune responses to vaccinations and increasing vaccine-related side effects. 

Changing temperatures

Climate change increases the possibility of temperature fluctuations during storage and transit and this is especially problematic in areas with extremely high temperatures.

According to the study, vaccine stability, longevity, and efficacy can all be negatively impacted by compromised storage and transportation, which can result in functional or physical harm. Extremely low temperatures may change the structure of vaccine components, affecting their capacity to elicit the intended immune responses, whereas high temperatures can denature vaccine proteins, making them less efficient or even ineffective.

Variations in humidity and precipitation can also damage vaccine formulations by allowing moisture to enter or evaporate, which might reduce the stability of vaccines and perhaps shorten their shelf life, the study found.

Disrupting systems

Climate change exacerbates vaccine inequity indirectly by disrupting health systems and services, including vaccination programmes, impeding vaccine distribution and altering climate-related infectious disease patterns. As a result of a changing climate, the likelihood, frequency and severity of extreme weather events are increasing, which necessitates better preparation in healthcare systems.

Events such as heatwaves, hurricanes and floods present numerous challenges to health systems, for example, affecting operations, damaging facilities, and impacting healthcare professionals and patients. These impacts extend to vaccine services and probably result in behaviour and outcome changes, making it more challenging to provide access to marginalised populations.

The probability, frequency, and intensity of extreme weather events are rising due to climate change. Natural disasters, including hurricanes, floods, and heat waves pose a number of problems for health systems, including operational disruptions, facility damage, and effects on patients and healthcare workers. 

The study said that by upsetting health systems and services, such as vaccination programs, obstructing vaccine distribution, and changing patterns of infectious diseases linked to climate change, climate change indirectly makes vaccine inequality worse. 

Need to build resilience 

The study said that building resilient vaccine infrastructure in climate-vulnerable regions, including distribution and production can help address these concerns. This includes setting up mobile immunisation units to reach outlying areas and more reliable cold chain systems. 

Since marginalised communities are frequently disproportionately impacted by disasters and have limited access to healthcare facilities, it is important to identify such communities and put mechanisms in place to promote equitable access to vaccines, the study said.

The study also recommended further research into the molecular mechanisms underlying how climate change impacts the safety and efficacy of vaccines. Incorporating vaccinations into plans for emergency preparedness and response, such as communication tactics to improve vaccine literacy and planning for quick deployment in an emergency, can also be helpful, said the study.

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