COVID-19 Vaccines: Graded Dosing Protocol / Antibody Persistence

By Amy Orciari Herman

Edited by David G. Fairchild, MD, MPH, and Lorenzo Di Francesco, MD, FACP, FHM

Check out today's highlights on the COVID-19 vaccines:

Graded dosing protocol: Two patients who required treatment for hypersensitivity reactions to the first dose of the Moderna mRNA COVID-19 vaccine were able to receive their second dose without major complications when it was administered in graded doses, according to a report in the Annals of Internal Medicine. After reactions to the first dose (e.g., pruritus, urticaria), the two female patients underwent allergy testing; skin prick testing was negative for the vaccine components, while intradermal testing showed an allergy to the vaccine. Subsequently, the second dose of vaccine was administered as a series of five injections given every 15 minutes, beginning with 0.05 mL of diluted vaccine and ending with 0.2 mL of full-dose vaccine. One patient had no symptoms, while the other developed self-resolving pruritus after the second and fifth injections. Three to four weeks later, patients' antibody tests showed IgG antibodies against the SARS-CoV-2 spike protein. The researchers conclude that rather than immediately ruling out the second vaccine dose for such patients, referral to an allergist or an immunologist "should be considered." They note that their findings do not apply to patients with anaphylaxis after the first COVID-19 vaccine dose.

Antibody persistence: SARS-CoV-2 antibody levels were high in 33 healthy adults roughly 200 days after receiving the second dose of the Moderna vaccine, researchers report in the New England Journal of Medicine. In particular, virus neutralizing activity was maintained in all participants throughout follow-up. The half-life of live-virus neutralization was estimated at 202 days.