When the Climate Changes, So Does the Fight Against Disease: What It Means for Vaccination

This informal CPD article ‘When the Climate Changes, So Does the Fight Against Disease: What It Means for Vaccination’ was provided by Cima Care, who offer extensive training in vaccination and public health, advancing global health initiatives.

Many people may associate climate change with rising seas or extreme weather. Far fewer realise that it is also quietly reshaping 'vaccination' as one of medicine's greatest achievements. From the moment a vaccine is manufactured to the day it enters a child's arm, climate change can interfere at almost every step — and the consequences matter for every family, in every country.

Heat and the Hidden Fragility of Vaccines

Vaccines are biological products, and many are sensitive to temperature. When they are exposed to excessive heat, their potency can be reduced, sometimes irreversibly. The temperature fluctuations during storage or transport can compromise vaccine effectiveness. This risk becomes more pressing as global average temperatures continue to rise. (1)

This matters even in well-resourced settings, because cold-chain failures and refrigeration system breakdowns can occur during heatwaves or power outages. In lower-income regions, the challenge is significantly greater, where maintaining stable vaccine storage is already difficult, and climate-related disruptions add further pressure. (2)

Diseases Are Moving — and Vaccines Must Keep Up

As temperatures rise, the geographic range of disease-carrying insects, such as mosquitoes, is expanding into areas previously unaffected. The US Centers for Disease Control and Prevention (CDC) notes that North America now faces growing threats from diseases such as dengue, West Nile virus, and Lyme disease, illnesses that were once largely confined to tropical or subtropical climates. (3)

Water-borne diseases such as cholera also become more prevalent in the aftermath of floods and droughts. Encouragingly, research highlights that vaccines and vaccination programmes can serve as an important mitigation strategy against these climate-driven consequences, reducing the burden of disease even as its patterns shift. (4)

Melting Ice, Ancient Threats

Perhaps the most remarkable, and least discussed dimension of this issue concerns the world's glaciers and permafrost. As global warming thaws these ancient frozen landscapes, long-dormant microbes and viruses are being exposed. A study examining Tibetan glacier ice reported the discovery of 28 novel virus groups, some dating back approximately 15,000 years. (5)

While the immediate public health risk of these discoveries remains under investigation, the findings serve as a reminder that climate change may introduce infectious disease challenges that are genuinely novel — pathogens for which no existing vaccines or immunity exist. This underscores the value of sustained investment in vaccine research and rapid-response development capacity. (6)

When Storms Disrupt Immunisation Programmes

Extreme weather events — floods, droughts, cyclones, and wildfires — not only cause immediate physical harm. They also disrupt healthcare systems and sever the connections between families and the health services they rely on. Research shows how flooding or severe drought can displace communities from their homes and, in doing so, from their usual vaccination clinics. In some regions, residents have abandoned villages in search of arable land, leaving them without access to health facilities and disrupting their children's vaccination schedules. (7)

Research in sub-Saharan Africa provides a specific illustration of these effects. An analysis of national survey data from 22 countries found that drought was associated with lower childhood vaccination rates, although the strength of the association differed by country. (8) These findings highlight the complex relationship between environmental crises and vaccination uptake, a relationship that extends well beyond logistics into trust, priorities, and access. (9)

Displacement, Migration, and the Challenge of Herd Immunity

Climate-related displacement is one of the defining public health challenges of our era. When large populations move, whether due to flooding, desertification, or conflict worsened by resource scarcity, vaccination coverage can deteriorate rapidly. The 2022 floods in Pakistan, for example, displaced approximately 8 million people, including Afghan refugees, creating significant challenges for maintaining routine immunisation. (10)

Mass migration and rapid urbanization lead to the formation of under-vaccinated populations in cities and camps. A review in 2024 further identified connections between immigration enforcement policies and decreased vaccination rates among migrant communities. (11)

These gaps in immunization coverage are not just individual issues; when herd immunity falls below the necessary threshold to prevent disease transmission, entire communities, including those who are vaccinated, become vulnerable. (12)

The Economic Dimension: Funding Immunisation Under Pressure

Climate change also exerts pressure on the financial systems that support public health. Countries facing recurrent extreme weather events bear heavy economic costs in disaster response and recovery, often at the expense of longer-term investments in healthcare and prevention. Recognising this, the world is scaling up investment in climate-resilient health systems and building international partnerships to address these interlinked challenges. (13)

Without sustained and adaptive funding, the gains achieved in global vaccination coverage over recent decades risk being eroded — not because vaccines have changed, but because the systems that deliver them are under unprecedented strain. (14)

Innovation in Response: Climate-Resilient Vaccines

Necessity, as ever, is driving scientific creativity. Researchers and manufacturers are working to develop vaccines that can resist higher temperatures and more challenging storage conditions, reducing dependence on refrigeration and therefore on vulnerable supply chains.

Several advances are particularly noteworthy:

• A novel thin-film platform has been developed that preserves live viruses, bacteria, antibodies, and enzymes without refrigeration for extended periods. (15)
• A study demonstrated that a live-attenuated vaccine kept its efficacy after at least two months of storage at 40°C when stabilised using a sugar-film technique. (16)
• Research advances in mRNA vaccine resilience suggest that future formulations may be storable at a wider range of temperatures, making them more deployable in lower-resource settings. (17)

The COVID-19 pandemic displayed that vaccine development can be dramatically accelerated under pressure. A 2023 review assessed how emerging technologies, including mRNA platforms, have shortened development and manufacturing timelines compared with traditional approaches, and considers what this means for pandemic preparedness in a world of rapidly shifting disease patterns. (18)

A Growing International Response

There are motivating indications that the international community is beginning to treat climate change as a health — and specifically a vaccination — issue, not merely an environmental one. Decisions are to include climate change risk among the criteria that inform Vaccine Investment Strategy, recognising that climate-related disease burden should shape which vaccines receive prioritised support and funding. Such processes involve qualitative research and expert consultation on the impact of climate change on disease outbreaks, geographic spread, and social equity in vaccine access. (19)

Key Takeaways

• Rising temperatures can compromise vaccine potency during storage and transport, placing increased demands on cold-chain infrastructure worldwide.
• Changing climates are altering the geographic range of disease-carrying insects and water-borne pathogens, requiring vaccination strategies to adapt accordingly.
• Extreme weather events and climate-driven displacement disrupt vaccination access, creating under-immunised communities and threatening herd immunity.
• Economic pressures related to climate change can reduce the funding available for immunisation programmes, particularly in lower-income countries.
• Thermostable vaccines, mRNA platforms, and innovative delivery technologies are under active development as part of the scientific response to these challenges.
• International bodies are beginning to integrate climate risk into vaccine investment and policy decisions — a necessary step towards climate-resilient immunisation.

Vaccination has been among humanity's most effective tools against infectious diseases. Understanding how climate change challenges that achievement — and how science and policy are responding — is relevant to everyone who values public health. The relationship between a warming planet and the stability of our immunisation systems is complex. Still, the broad direction is clear: Addressing climate change and protecting global vaccination coverage are, increasingly, the same challenge. 

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