Vaccine effectiveness reduces over time. That’s why many childhood vaccines require multiple doses and boosters. According to federal health officials, research has shown reduced vaccine effectiveness against COVID-19 infection over time. With the highly contagious delta variant sweeping our nation and other parts of the world, there’s concern that protection from the vaccines might decline even more over the coming months, especially for those at higher risk for severe infection and those who were among the first to be vaccinated. Getting a booster shot is a good way to stay ahead of the virus and increase protection.