1. A study examined the effect of needle length when administering the hepatitis B vaccine to obese adolescents, finding that those who received the standard 1-inch needle had lower antibody titers compared to those who received the longer 1.5-inch needle. 2. Prophylactic administration of paracetamol after vaccination was found to reduce febrile reactions but also reduce antibody responses to several vaccine antigens. 3. Influenza vaccination was found to reduce mortality risk among the elderly and protect against all-cause mortality in patients with COPD.