Vaccination matters.
https://www.euronews.com/2021/10/07/ukraine-confirms-case-of-polio-in-18-month-old-toddler
Ukraine has its first case of Polio in more than 6 years. An 18 month old girl from Rivne oblast is now paralyzed. The girl's parents said they did not vaccinate her for religious reasons.
In 2015, Ukraine saw 2 cases of Polio, the first cases of Polio in Europe since 2010. Prior to that the country last saw a Polio case in 1996.
In 2008, the Polio vaccination rate was a very robust 91%. That fell to 15% in 2015. For herd immunity, Polio needs a vaccination rate around 80-85%.
At present only 53% of Ukrainian children under 1 year old are vaccinated against Polio thus far in 2021. Rivne oblast has only 48.9% vaccinated. In Kherson oblast only 40.7%.
Vaccine hesitancy is a real crisis in the country. Vaccination rates have never really recovered since 2008 when a 17 year old boy's death was falsely attributed to a MMR vaccination. Euromaidan and the war with Russia further harmed vaccination efforts. The country had a massive Measles epidemic in 2018 and 2019 after Measles vaccination rates fell down to 30%. And this vaccine hesitancy is now imperiling the containment of the coronavirus pandemic.