Booster Shots for mRNA COVID-19 Vaccines Offer Improved Protection From Variants of Concern

The investigators found that antibodies generated by a single dose of the Pfizer-BioNTech vaccine was less effective at neutralizing variants of concern, but the second dose dramatically increased responses to virus variants.

An autumn booster dose of COVID-19 vaccines could be an effective way to protect individuals from current and future variants of concern, according to a study published in Science Translational Medicine. The investigators found that antibodies generated by a single dose of the Pfizer-BioNTech vaccine was less effective at neutralizing variants of concern, but the second dose dramatically increased responses to virus variants.

The investigators examined a cohort of health care workers who were vaccinated with the Pfizer-BioNTech vaccine. Approximately half of the participants were naturally pre-exposed to the virus, and the investigators compared the antibody responses of those who had been infected with SARS-CoV-2 with those who had not.

“We showed that the individuals with past infection produced more antibodies following each dose of vaccine than those who hadn’t been exposed,” said Jonathan Ball, PhD, in a press release. “We also showed that this increased antibody response was more effective against some of the variants of concern, such as the Beta and Gamma variants. In essence, natural infection has mimicked the effects of an additional vaccine dose, and our data clearly shows that this additional antigenic exposure produces an extra boost to the overall virus-killing antibody response that is more effective against variants of concern. Our results support the UK Government’s plan to provide a booster jab in the autumn as an effective strategy in protecting people against these variants.”

According to the investigators, the study data suggest that the immunity generated from SARS-CoV-2 infection results in lower levels of protection against viral variants, whereas vaccination greatly increases the number of neutralizing antibodies. By extension, those who have not been infected should receive both the initial dose and a booster vaccination.

“Having access to information on infection for over a year before the second dose of the vaccine has made it possible to identify the effects of previous SARS-CoV-2 infection compared to the effects of the vaccine on antibody responses,” said Ben Ollivere, MD, in the release.

The data were collected via pseudotyping, which involves using a modified mouse virus that emits light once it enters a cell. This virus is then covered with SARS-CoV-2 spike proteins from a number of different viral variants to test the antibodies of the participants against several variants of concern.

“The readout is simple—if the health care worker has neutralizing antibodies, they block the virus from entering the cell, and no light is emitted,” said Richard Urbanowicz, PhD, in the release. “If they don’t have virus neutralizing antibodies, then the pseudotypes enter the cell and we can measure the light that they emit once inside.”

REFERENCE

Covid-19 booster jab in the autumn will offer better protection against variants of concern, suggests new study [news release]. EurekAlert; August 10, 2021. Accessed August 11, 2021. https://www.eurekalert.org/news-releases/924940