A vaccine that doesn’t fit how countries operate won't reach more people, however advanced it is. Here are five ways that experts say will help keep vaccines at the right temperature as well as make them easier to deliver:

Mosquitoes spread some of the world’s deadliest diseases. Now researchers are flipping the script and testing whether they could be turned into something entirely different: vaccine delivery systems for wild bats. For #WorldMosquitoDay#, explore how “flying vaccines” could deliver protection against diseases like rabies and Nipah:

Apac, in northern Uganda, is known for having the highest rate of mosquito bites in the world. But there's good news for this hard-hit region: early indicators suggest that the new malaria vaccine is blunting the severity of the malaria infections the mosquitoes are spreading. The full story: #WorldMosquitoDay#

New research suggests that viruses that lie dormant in our bodies for many years could be reactivated by a severe COVID-19 infection. In a study of 1,154 people hospitalised by COVID-19, nearly half showed evidence of reactivation of at least one chronic virus. Learn more:

For around 2,000 years, Western medicine explained illness through the balance of four bodily “humours”: Blood, phlegm, yellow bile and black bile. The theory was wrong. But ancient Greek physician Hippocrates and his followers still helped lay foundations for scientific medicine that endure today:

🌍 On #WorldHumanitarianDay#, CORE Group recognizes the humanitarian workers who continue to reach communities with essential health services in some of the world’s most challenging settings. Through 𝗭𝗜𝗣, @Gavi’s 𝗛𝘂𝗺𝗮𝗻𝗶𝘁𝗮𝗿𝗶𝗮𝗻 𝗣𝗮𝗿𝘁𝗻𝗲𝗿𝘀𝗵𝗶𝗽𝘀, humanitarian partners are working to reach children with life-saving vaccines in communities affected by conflict and crisis. A new #VaccinesWork# story, “𝗗𝗼𝗻'𝘁 𝗮𝘀𝗸 𝗳𝗼𝗿 𝗮𝗻𝘆𝘁𝗵𝗶𝗻𝗴 𝗲𝗹𝘀𝗲. 𝗝𝘂𝘀𝘁 𝗮𝘀𝗸 𝗳𝗼𝗿 𝘀𝗮𝗳𝗲 𝗽𝗮𝘀𝘀𝗮𝗴𝗲”: 𝗻𝗲𝗴𝗼𝘁𝗶𝗮𝘁𝗶𝗻𝗴 𝗮𝗰𝗰𝗲𝘀𝘀 𝗳𝗼𝗿 𝘃𝗮𝗰𝗰𝗶𝗻𝗲𝘀 𝗮𝗺𝗶𝗱 𝗰𝗼𝗻𝗳𝗹𝗶𝗰𝘁, takes us behind the scenes of this work, exploring how humanitarian teams navigate insecurity, build trust, and negotiate safe access to reach children in hard-to-reach and conflict-affected communities. 🔗 𝗥𝗲𝗮𝗱 𝘁𝗵𝗲 𝘀𝘁𝗼𝗿𝘆: Today, we honor the people behind this work and their commitment to reaching communities wherever they are. #ActForHumanity# #WorldHumanitarianDay# #HumanitarianAction# #Immunization# #VaccinesWork#

Fragile, conflict and humanitarian settings are home to some of the world’s most vulnerable children. From 2026-2030 @Gavi will invest almost US$ 3 billion in immunisation support to ensure we reach more of these children than ever before. #WorldHumanitarianDay#

Reaching children with essential vaccines in high conflict settings can take months of negotiation, trust-building and careful security planning to reduce risk. When Gavi’s ZIP Humanitarian Partnerships programme began in 2022, the @RESCUEorg-led REACH Consortium determined that vaccination teams could safely reach just 16% of targeted areas due to conflict and access challenges. Today, the programme can deliver life-saving immunisation services across all targeted locations. On #WorldHumanitarianDay#, meet the negotiators and local partners making that access possible: via @CoreGroupDC

For #WorldHumanitarianDay#, a glimpse of what humanitarian impact can look like on the ground. In Sudan, war has displaced millions of people and disrupted vital health services, supply routes and access to routine vaccination. Yet despite battling trauma and the threat of violence, health workers continue to show up, carrying cold boxes, tracking vaccination records and travelling to reach children with protection against diseases including measles and polio. As one health worker explained, “Vaccines are about protecting our children.” These photographs by Magnum photojournalist Salih Basheer capture what it takes to keep essential health services moving through a crisis. 🔗:

❓“Will giving my baby multiple vaccines at once overload their immune system?” 💬 The quick answer: No. Decades of studies confirm that multiple vaccines don’t overwhelm immunity, don’t increase infection risk and don’t cause chronic illness. The data, on VaccinesWork: