At least one-fifth of patients with chronic medical conditions who received two doses of an mRNA Covid-19 vaccine had insufficient antibody levels even 14 days after the second dose, observed a recent study led by Dr Michael E. Wechsler, director of the National Jewish Health Cohen Family Asthma Institute in Denver. The study findings, published in CHEST, found that among the 360 patients analysed for the study who had received two doses of the Pfizer/BioNTech (64%) or Moderna (36%) vaccines, 21 percent of patients had no antibodies after the second dose. 24 percent of those who received the Pfizer-BioNTech vaccine and 16 percent of patients who received the Moderna vaccine had negative antibody responses. The researchers highlighted the need for patient education regarding these issues and urged immunocompromised patients to take precautions even if they are fully vaccinated.