The World Health Organization has recommended booster shots for people with weak immune systems as they are less likely to respond adequately to the standard course of vaccinations.
On Monday, the World Health Organization’s (WHO) 
vaccine advisory group said that people with compromised immune systems should be given a 
Covid-19 booster shot.
“Moderately and severely immunocompromised persons should be offered an additional dose,” the WHO’s Strategic Advisory Group of Experts on Immunization said. “These individuals are less likely to respond adequately to vaccination following a standard primary 
vaccine series and are at high risk of severe 
Covid-19,” they added.
The WHO has previously warned developed nations against administering booster shots, claiming that they should be focusing on sharing their 
vaccines with poorer nations around the world to ensure a larger proportion of the global population is inoculated.
Last week, the European Medicines Agency (EMA) recommended that people with a weak immune system receive a third dose of either the 
Pfizer or Moderna 
Covid-19 
vaccine.
The EMA noted that the third dose should be given 28 days after the second dose is administered but admitted there is little scientific evidence for the booster shot in people with weak immune systems. It said it is “expected that the extra dose would increase protection at least in some patients.”
Prior to the EMA announcement, many nations in Europe had already started administering booster shots more broadly to older generations amid concerns about waning efficiency over time.
Israeli research suggests that the administration of a third dose of 
Pfizer to the non-immunocompromised population produces 10 times more antibodies than the second dose.