Who Needs Just One mRNA COVID-19 Vaccination?

The journal Vaccine published a new study on July 21, 2021, saying 'there is a lack of mRNA vaccine effectiveness data about patients with a previous diagnosis of COVID-19.'

Reactogenicity is a part of the safety profile evaluation of a given vaccine. It refers to the potential for expected and unexpected local or systemic adverse reactions after vaccine administration.

This study analyzed the side effects of 311 patients after the first dose of the Pfizer-BioNTech COVID-19 (Comirnaty) vaccine in France. This report is a comparative study of post-vaccination adverse events between vaccine recipients with a COVID-19 pre-existing immunity and naive individuals.

Among the study participants with prior SARS-CoV-2 virus infection, 19/20 (95%) reported at least one adverse event, 18 (90%) at least one local reaction, and 13 participants (65%) systemic side effects. In addition, five participants had to lie down for 24-48 hours.

In this study, the rate of reported adverse events was lower than those disclosed in previous safety studies. This is probably related to the fact that this is a real-world study, patients are warned in advance of vaccine side effects and are self-reported and unsolicited.

Some recent studies have highlighted that a single dose of Pfizer-BioNTech vaccine-elicited rapid immune response in vaccinated individuals with pre-existing immunity and wost-vaccination antibody titers similar to or higher than those seen in naive participants who received two doses of vaccine.

These study authors also suggested that the vaccine systemic reactogenicity after the first dose was more pronounced in people with pre-existing immunity and appeared to be similar to the side effects reported for the second dose in vaccine trials.

These data, combined with current knowledge of the immunological response to SARS-Cov-2 and the phenomena of reinfection, have led to a recent modification of the vaccination strategy in France, say these researchers.

According to the French Health Authority Haute Autorite de Sante, people with a medical history of COVID-19 should receive only one (mRNA or adenovirus-vectored) vaccine dose except for immunocompromised patients who may need two doses.

These researchers concluded 'that vaccine recipients experienced more frequent reactogenicity after a first dose of the Pfizer-BioNTech COVID-19 vaccine cthannaive individuals. And mRNA vaccine recipients with prior COVID-19 reported more, but no more serious, side effects than naive participants.'

Note: The study protocol followed the ethical guidelines of the declaration of Helsinki and was approved by an institutional review board. A study limitation is all the data collected are based on self-reported, including COVID-19 exposure status.

The study authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.