First real-life data on COVID-19 vaccine effectiveness against hospitalisation and severe disease from the eastern part of the WHO European Region

While randomised trials led to licensing of different COVID-19 vaccines, it is also vital to study vaccine effectiveness (VE) in real-word settings.Those studies can provide robust and important data for the public and shape COVID-19 vaccine policy.The European Centre for Disease Prevention and Control regularly publishes updates on VE from European Union (EU) countries. 1However, data on VE from non-EU countries of Western Balkan and Eastern Europe have so far not been reported.There are also differences in COVID-19 vaccine uptake across Europe.Among EU member countries, vaccine refusals and hesitancy are highest among former communist countries of Central and Eastern Europe. 2 Yet, vaccine uptake among non-EU member countries of the WHO European region is even lower (Table 1).There are many factors that contribute to vaccine hesitancy.It has been suggested that the lack of trust towards health care professionals and governments plays a major role in post-communist Eastern and Central European countries. 2n this issue of The Lancet Regional Health -Europe Katz MA et al. 3 report data on VE against hospitalisation from 5126 hospitalised adults meeting the WHO severe acute respiratory infection (SARI) case definition 4 from 25 hospitals from six middle-income countries of the eastern WHO European region (Albania, Georgia, North Macedonia, Serbia, Kosovo, and Kyrgyzstan).The study was conducted between 1st January 2022 and 23rd November 2023, at a time when many people might have acquired some immunity because of past SARS-CoV-2 infection.In their analytical approach, the authors followed the WHO recommendations on how to conduct a VE test-negative study. 4A test-negative casecontrol study implies that persons hospitalised for SARI are compared based on whether SARS-CoV-2 was detected by a molecular test.Those who test positive are cases and those who test negative are controls.VE against hospitalisation is then calculated by comparing the odds of vaccination between cases and controls, while adjusting for confounders.The test-negative