Several studies have found as few as 45 per cent of people with multiple myeloma may develop protective levels of coronavirus-fighting antibodies after getting the vaccine.
Centers for Disease Control and Prevention has tracked dips in protection, especially among older Americans who were among the first people vaccinated last winter.
The government has authorized an extra dose of the Pfizer or Moderna vaccines for people with weakened immune systems to try to improve their response.health authorities urged booster doses of the Pfizer vaccine for everyone 65 and older once they are at least six months past their initial vaccination, along with other people at high risk.