COVID-19 is a respiratory disease caused by the SARS-CoV-2. SARS-CoV-2 belongs to the family of RNA-positive enveloped viruses. In early 2020, SARS-CoV-2 caused a global pandemic. A third of those infected are asymptomatic. Most of those infected have mild symptoms without pneumonia. People with a severe form of the disease have pneumonia, dyspnea, hypoxia and oxygen saturation levels less than 94%. Older people and people with comorbidities such as chronic lung diseases, tumors and immunodeficiency are at increased risk of developing a severe form of the disease and death. Despite the rapid development of vaccines, each vaccine has gone through the standard preclinical and clinical stages of development. Vaccination is recommended for everyone older than 6 years of age. Four vaccines are widely available in the Republic of Croatia. Two registered vaccines belong to adenovirus vector vaccines. Those vaccines are Vaxzevria-AstraZeneca and Johnson&Johnson/Janssen. The other two registered vaccines belong to mRNA vaccines. Those vaccines are Comirnaty-Pfizer-BioNTech and Spikevax-Moderna. All vaccines have shown high effectiveness against the severe form of the disease and the fatal outcome. Common local and systemic side effects after vaccination are fever, chills, myalgia, headache and reactions at the site of administration. These side effects don't prevent people from performing daily activities. More severe side effects such as thrombosis with thrombocytopenia, myocarditis and Guillain-Barre syndrome are rare. Trials have shown that the risk of infection is higher than the risk of side effects.