A recent study shows that two doses of mRNA (Pfizer-BioNTech or Moderna) or one dose of viral vector (Johnson & Johnson) COVID-19 vaccines were insufficient to produce adequate immunity to a lab-created Omicron variant or pseudovirus.
The Omicron pseudovirus infected cells at a higher rate than other pseudovirus variants.
The results demonstrated a booster dose of an mRNA COVID-19 vaccine provided the best immune protection from the Omicron pseudovirus.
Since its first detection in South Africa and Botswana in November 2021, the SARS-CoV-2 variant Omicron (B.1.1.529)Trusted Source has spread rapidly globally. Currently, Omicron is the leading variant of concernTrusted Source in the United States, accounting for about 98% of COVID-19 cases in the week ending January 8, 2022.
All viruses, including SARS-CoV-2, constantly change or mutate to form new variants. Mutations of the virus may result in the decline of the variant, while others cause the virus to thrive.
Dr. William Schaffner, professor of infectious diseases at the Vanderbilt University Medical Center in Nashville, provided some background in an MNT interview.
He explained: “When [SARS-CoV-2 viruses] mutate, they can, on occasion, […] create a variant virus that has new characteristics, you might call it a new personality, and the Omicron […] is one of those. Its surface protein compositions are similar to previous variants but a little bit different.”
Dr. Schaffner added: “So when that happens, the vaccines […] designed against the original [SARS-CoV-2] strains produce antibodies that […] [partially match] the surface structure of the Omicron variant. As a consequence, the protection is not as complete.”
There are currently three COVID-19 vaccinesTrusted Source available in the U.S. The primary series consists of two doses of an mRNA vaccine (Pfizer-BioNTech or Moderna vaccines) or one dose of a viral vector vaccine (Johnson & Johnson).
The immune response to COVID-19 vaccines may wane over time and as new variants evolve. Boosters can help combat diminishing neutralizing antibody responses, but it is unknown how well current vaccines protect against Omicron.
This led researchers at the Ragon Institute of Massachusetts General Hospital, Massachusetts Institute of Technology, and Harvard to conduct a study to investigate the effectiveness of the primary series of COVID-19 vaccines and a booster dose of an mRNA vaccine.
They study’s results appear in the journal Cell. The researchers used a laboratory test validated in previous studies called a pseudovirus neutralization assay.
Pseudovirus neutralization assay
The scientists created harmless versions or pseudoviruses of the original strain (wild-type)Trusted Source, Delta, and Omicron SARS-CoV-2 viruses. The researchers then used the assay to test blood samples from 239 vaccinated participants (111 with Pfizer-BioNTech, 88 with Moderna, and 40 with Johnson & Johnson).
The study included people residing in Chelsea, MA — an area with a high rate of COVID-19 — and employees of the Massachusetts General Brigham healthcare system. Participants ranged from 18–78 years old, and 63% were female.
The study stratified participants into five groups:
people who received the primary vaccination series in the past 3 months and never developed COVID-19 —recently vaccinated
people who received the primary vaccination series in the past 6–12 months and never developed COVID-19 —distantly vaccinated
people who received the primary vaccination series in the past 6–12 months and developed COVID-19 — distantly vaccinated with infection
people who received a booster dose of the Pfizer or Moderna vaccine in the past 3 months and never developed COVID-19 — booster