Wetin be vaccines, how dem dey work and why pipo dey sceptical?
Vaccines don save tens of millions of lives for di past century, yet for many kontris pipo wey sabi bodi mata don identify trend wey dem call "vaccine hesitancy" wey mean increase for pipo wey no wan do vaccination.
Di World Health Organization (WHO) dey concerned and don tok say na one of di 10 threats to global health for 2019.
- No more religion excuse for vaccination
- Ebola outbreak for DR Congo, six months afta don claim nearly 400 lives
How dem discover vaccination?
Before vaccines exist, di world na dangerous place, as millions of pipo dey die everi year to illness wey dem fit prevent.
Na di Chinese first discover di early form of vaccination for di 10th Century: "variolation" wey go involve exposing pipoe wey dey bodi dey kampe to tissue from di scabs wey cause di disease to build immunity.
Afta eight centuries waka pass, Edward Jenner wey be doctor from Britain notice how milkmaids dey catch mild cowpox, but no catch di deadly smallpox.
Smallpox na disease wey pipo fit catch if dem dey around one another and e kill about 30% of the pipo wey catch am. Pipo wey survive dey get scars or dem go go blind.
For 1796 Jenner carry out experiment ontop eight-year-old James Phipps.
Di doctor insert pus from cowpox wound into di boy, as e get di symptoms.
Once Phipps recover, Jenner insert smallpox inside di boy but he remain healthy. Di cowpox make am immune.
For 1798, dem publish di results and dem form di word vaccine - from di Latin "vacca" for cow.
Wetin be di successes?
Vaccines don help reduce di damage wey plenti disease don cause.
About 2.6m people don die from measles every year before dem introduce di first vaccination for di disease for di 1960s. Vaccination cause 80% drop for measles deaths between 2000 and 2017 worldwide, according to WHO.
Only few decades ago, paralysis or death na real concern as polio dey affect millions of pipo. Now polio don almost disappeared.
Why some people dey refuse vaccination?
Pipo don dey take side eye look vaccines since modern vaccines comot.
Before people no like am sake of religious reasons, because dem think say vaccination dey unclean, or say e dey affect dia freedom of choice.
For di 1800s so-called anti-vaccination leagues start across Britain, and dem tok say dem want another way to fight disease, like to keep patients on dia own.
For di 1870s, the first anti-vaccination group for America start after British anti-vaccination activist, William Tebb visit di kontri.
One of di pipo from recent history of di anti-vaccination movement na Andrew Wakefield.
For 1998, doctor wey dey London publish report wey link autism and bowel disease to MMR vaccine.
MMR na three-in-one vaccine wey dem dey give to young children to fights measles, mumps and rubella, or German measles.
Even though dem no regard di report and dem comot Wakefield from medical register for di UK, di number of children wey dem vaccinate after wetin im tok drop.
For 2004 alone, 100,000 fewer children received MMR vaccine for di UK - this one lead to rise for measles cases further down di line.
Politics also don enter dis vaccines mata.
Italy's interior minister Matteo Salvini dey support anti-vaccination groups.
US President Donald Trump, link vaccinations to autism without evidence, but e don tell parents vaccinate dia children.
International study of attitudes to vaccination show say overall confidence for vaccines dey positive, E dey lowest for di European region, and France get participants wey no dey confident.
Wetin be di risks?
When pipo dey vaccinated e dey prevent di spread of disease wey fit protect those wey never developed immunity or wey no fit get vaccinated.
Dis one na herd immunity and when it breaks down e fit affect wider population.
Di pipo wey gats be vaccinated to maintain herd immunity different between diseases, but measles dey more dan 90% and polio more than 80%.
England's most senior doctor warn pipo last year say too many people get misleading information about vaccines for social media, and US researchers find say Russian bots dey sow discord online as dem dey false information about vaccines.
Di proportion of children around di world wey don receive recommended vaccines never change at 85% for the past few years, according to World Health Organization.
Di WHO tok say vaccines continue to prevent between two and three million deaths worldwide every year.
Di biggest challenges to vaccination, and di low rates of immunisation, dey for kontris wey get history of conflict and very poor healthcare systems, including Afghanistan, Angola and di Democratic Republic of Congo.
But di WHO also identify I don't care attitude as ogbonge issue for developed countries - na because pipo don forget di damage disease dey cause.
Produced by Roland Hughes, David Brown, Tom Francis-Winnington and Sean Wilmott