our immune system is critical for fighting off disease, but millions of people around the world are immunocompromised. This means their immune systems have been weakened either by a genetic disorder or by chronic illnesses like AIDS, Cancer or Diabetes. Living with such diseases is hard enough at the best of times, but in the age of COVID-19 a positive test could be a death sentence. As nations race to get their populations vaccinated those with an already compromised immune system are often not at the top of the list. How can overburdened medical systems keep these at risk people from falling behind?