Antibody Responses after Additional COVID-19 Vaccines in Immunocompromised Persons

June 6, 2022

The Lancet recently conducted a literature review of antibody responses after COVID-19 vaccination in immunocompromised persons published between July 1, 2020, and September 27, 2021. Authors aggregated information from 23 studies with a total of 1722 persons who received an additional dose of a COVID-19 vaccine due to their immunocompromised status.

Of the 23 studies included in the review, 18 exclusively offered mRNA vaccines, versus 2 offering AstraZeneca or Johnson & Johnson as additional doses after an mRNA primary series. Additional doses were administered 1-3 months after a primary series in 20 studies. Overall, seroconversion rates (method of assessing vaccine efficacy) after two COVID-19 vaccine doses were 99% for immunocompetent persons, versus 78% for persons with immune-mediated inflammatory disorders.

“No studies reported on the efficacy or effectiveness of an additional COVID-19 vaccine dose among people who are immunocompromised.” That being said, studies stated that an additional dose “appeared to have a modest additive effect” on immunogenicity levels. Also, reactions after receiving an additional dose were consistent with reactogenicity profiles after the first and second doses. Persons who elicited a low or undetectable antibody response after a primary series were able to elicit a median antibody response rate of 44%. It is still unclear how long protection after a third dose lasts, although it is assumed that the benefits of a third dose “are likely to outweigh the risks on the basis of the available data.”