The use of "solar direct-drive" refrigerators, which do not require fuel or batteries, has increased child vaccinations in the poorest rural provinces of the DRC by 50% in the last year, according to Gavi. This has contributed to a significant reduction in child mortality in the DRC compared to two decades ago. Over 18 million children were vaccinated last year for a deadly measles outbreak, which has slowed down recently. The world is now preparing for a larger immunisation campaign once COVID-19 vaccines become available. Distributing millions of vaccinations in Africa, a continent with weak health systems and limited electricity, will be a challenging task. It is uncertain whether current off-grid refrigerators can maintain the necessary temperature to store vaccines effectively. Refrigeration is crucial for distributing vaccines, with many requiring temperatures between 2 and 8 degrees Celsius (35-46 degrees Fahrenheit). Some COVID-19 vaccine candidates may need storage as low as minus 80C, which poses a challenge for distribution networks. Ensuring cold chain distribution for COVID-19 vaccines will require maintaining consistently low temperatures from manufacturers to remote rural areas. While advancements in refrigeration technology have saved many lives, African countries still face significant gaps in their distribution networks. Toby Peters, a professor specializing in cooling systems for food and medicine at the University of Birmingham in Britain, referred to the global logistical challenge of providing refrigeration for vaccines as one of the largest challenges ever faced. In sub-Saharan African countries with large rural populations, this challenge is even greater. William Clemmer, a doctor with IMA World Health, witnessed the difficulties faced by health centers in the DRC in the 1990s, where outdated kerosene-powered refrigerators often broke down, causing damage to vaccines. The introduction of solar direct-drive refrigerators in the past decade has revolutionized vaccine storage in remote areas, providing a reliable and cost-effective solution. These refrigerators, connected directly to solar panels, use thermal energy to keep vaccines cool for many days, regardless of weather conditions. In 2016, only 16% of rural health centers in the DRC had functioning refrigerators, but now nearly 80% are equipped with direct-drive solar units, enabling 24,000 monthly immunization sessions in the country's poorest provinces. This has led to a 50% increase in sessions from 2018 and has significantly improved vaccine delivery for children in sub-Saharan Africa. Karan Sagar, a doctor at Gavi, attributes a 25% increase in child vaccination rates in Africa over the past decade to the off-grid equipment. Since 2017, Gavi has spearheaded a $250-million initiative to distribute over 15,300 solar direct-drive fridges to three-dozen African nations, with the Democratic Republic of Congo receiving 3,400 units and Nigeria receiving 5,400 units. Last year, 87% of children in these African countries were administered the first dose of a vaccine for diphtheria, tetanus, and pertussis, showcasing the effectiveness of supply chains in reaching even the most remote communities. Moving vaccines quickly and safely from manufacturing sites to urban and rural areas in Africa will require various steps, with solar refrigerators being just one of them. Throughout the entire process of transporting vaccines, whether by airplanes, warehouses, trucks, motorbikes, bicycles, canoes, or even drones, it is crucial to maintain specific cold temperatures, similar to other perishable goods. Additionally, a much larger quantity of vaccines will be required, as health experts estimate that the COVID-19 vaccine will need to be administered to up to 750 million people in Africa alone, compared to the 115 million infants reached by typical child vaccination campaigns worldwide annually. In anticipation of this immense task, cold chain expert Peters is spearheading a government-supported initiative to assess Africa's requirements for distributing the eventual COVID-19 vaccine, collaborating with various nonprofit, commercial, and academic partners. Their approach is influenced by the success of Rwanda, a country in central-east Africa, which has made significant advancements in establishing efficient, environmentally-friendly cold chains for food and vaccine transportation. The system is centered on a single warehouse that acts as a cooling center for vaccines distributed to various healthcare facilities in Rwanda, including those in remote rural areas equipped with solar fridges. The World Health Organization reports that the vaccines are reaching over 95% of the population. However, replicating this success in other countries, particularly larger ones like Nigeria, will be a significant challenge. It will require a model similar to established food cold chains with larger commercial capacity. Peters stated that they have the knowledge to transport large quantities of fresh food from African farms to consumers in Europe, and they aim to apply this expertise to vaccines. However, the challenge lies in the ultra-cold storage requirements that COVID-19 vaccines may have, which current solar direct-drive fridges cannot handle. Rwanda and the DRC have experience with ultra-cold storage for vaccines during the Ebola outbreak, using "super thermos" coolers with synthetic alcohol ice to keep the vaccine at minus 60-80C for up to 6.5 days. Despite this success, the amount of vaccine needed for COVID-19 would be much greater. Sagar pointed out that very few African economies have the capacity for ultra-cold chain storage. Peters is optimistic that COVID-19 vaccines will only require standard cold storage temperatures of 2-8C, which can be provided by solar direct-drive refrigerators at rural health centers. However, he acknowledged that if the vaccines need to be stored at even lower temperatures, it will present a significant new challenge.