If there's a smell that will always remind me of the Democratic Republic of Congo (DRC), it is that of burning plastic. In front of homes, on the sides of hectic streets, people are getting rid of their rubbish by setting fire to great piles of it. With no other form of waste disposal available, this is their only option.
Through gaps in the crowds, I can see puddles of standing, dirty water. It will only get worse when the rainy season hits any day now. In summary, this is the perfect environment for a mosquito-borne disease to spread.
I am in Kinshasa, the capital of DRC, a city of more than 10 million inhabitants. And a city that is facing a giant threat: Yellow Fever.
The country's first cases of the deadly disease were detected earlier this year and the virus has since found its way to the capital, where large-scale transmission is a looming risk.
Luckily, there is a highly effective vaccine - but about 7 million people in Kinshasa alone have never been vaccinated.
I am here with Save the Children, supporting a government-run mass vaccination campaign - one of the largest ever in Africa - against Yellow Fever.
The Ministry of Health wants to vaccinate virtually every person in the city in just 10 days. Save the Children is helping in a suburb called Binza Ozone, where 340.000 are being vaccinated. That's 96% of the population. As the Ministry of Health puts it: 'Vacciner c'est aimer' ('to vaccinate is to love').
We've reached more than 300,000 people already. Outside every vaccination site I have visited so far, people have been queuing from the early morning hours to get their shot.
They have seen Yellow Fever outbreaks before. They know how the virus causes vomiting and diarrhoea, and has people shaking with peaks of fever. They know that in severe cases, it can turn their eyes and skin yellow; it can even lead to bleeding from the eyes and mouth. And they know there is no reliable cure for Yellow Fever. On average, one in every ten people who catch the disease will die.
For those 7 million people who are believed to be unprotected in Kinshasa, the outlook is scary. That's why people start queuing up for jabs at 7am - and sometimes revert to creative methods to get their turn.
One boy I met a couple of days ago came to a vaccination site, claiming he was sick with Yellow Fever. The local doctor only needed a quick look to know that the child was actually in the best of health. He had simply tried to jump the queue. He 'recovered' in seconds when it was suggested that he be placed in quarantine.
Despite the enormous effort of the DRC's health ministry, an incredible challenge remains: a global shortage of the vaccine. Vials can take more than a year to produce, and that is far too long to wait.
To bridge the gap, people receive smaller, so-called 'fractionalised' doses. This means they are given one fifth of a normal dose each, enough to protect them for at least a year. This will at least allow some time for global production to pick up speed.
The number of people at risk, the shortage of vaccine and the urgency of taking action create a working environment that can reasonably be described as extremely challenging. That's where Save the Children's Emergency Health Unit - a team made up of doctors, nurses and other experts - comes into the picture.
We make sure vaccines are kept cold from the moment they leave a central storage point until they reach the vaccination sites. We also make sure the medical waste is safely disposed of. These activities seem trivial. They are anything but that, in a country where temperatures soar above 30° Celsius and where roadside ditches and waste disposal sites are considered the same thing.
It's the complex and often unglamorous details that are key to halting the spread of Yellow Fever, to bringing this outbreak under control and to protecting Kinshasa's population - and its children.
Sarah Frattaroli is a communications coordinator for Save the Children's Yellow Fever response in the Democratic Republic of Congo.