Results of an analysis show that 3 doses of either Oxford/AstraZeneca COVID-19 or Pfizer BioNTech COVID-19 neutralizes the variant.
A third booster dose of either the Oxford/AstraZeneca COVID-19 or the Pfizer BioNTech COVID-19 vaccine raises antibody levels that neutralize the omicron variant, according to the results of a study from the Francis Crick Institute and the National Institute for Health Research University College of London Hospitals (UCLH) Biomedical Research Centre and published in The Lancet.
Investigators found that antibodies generated in the individuals who received just 2 doses of either vaccine were less likely to neutralize the omicron variant compared with the alpha and Delta variants.
Additionally, they found that the antibody levels dropped off in the first 3 months following the second dose, but a third dose raised the levels of antibodies that effectively neutralize the omicron variant.
Individuals who received the Pfizer vaccine for all 3 doses had antibody levels against the omicron variant after a third dose and were similar to those previously reached against Delta after just 2 doses.
Overall, antibody levels were nearly 2.5 times higher against omicron after 3 doses compared with after 2.
Higher levels of antibodies against the omicron variant were also found in individuals who received 2 doses of either vaccine and also reported previously having COVID-19 symptoms compared with those who did not previously have the symptoms.
Although levels of antibodies do not predict vaccine effectiveness, they are good indicators of protection against severe COVID-19. This study results confirm that 3 doses of the vaccine are essential to boost antibodies to quantifiable levels and maximize the amount of protection against severe disease and hospitalization.
“People who have queued outside vaccinations centers should be reassured that a vaccine booster is the best way of protecting them from Omicron,” Emma Wall, PhD, consultant of infectious diseases at UCLH, said in a statement.
“This new variant can overcome the immune blockade put in place by two vaccine doses, but thankfully following the third dose, neutralizing activity is robust in the vast majority of people. A third dose builds our defenses higher, making it harder for the virus to cause severe COVID-19,” Wall said.
Investigators analyzed 620 blood samples from 364 individuals who enrolled in the study. They used robust high throughput viral neutralization assays to test the ability of antibodies to block entry of the virus into cells against different variants of SARS-CoV-2, including omicron.
Investigators also included synthetic neutralizing antibodies that are in clinical use for COVID-19 treatment to test if these synthetic antibodies have neutralizing activity against variants of SARS-CoV-2, including omicron.
Investigators also found that sotrovimab, (Xevudy, GSK) a recently approved synthetic monoclonal antibody used to prevent disease in and treat individuals at risk of developing severe COVID-19, was able to neutralize the omicron variant.
“Now that we have established that boosters are effective against the omicron variant, future research will need to address the duration and persistence of this booster response. New variants of concern will continue to emerge as the pandemic evolves, so effective immune monitoring is needed to stay responsive and remain protected,” Sonia Gandhi, legacy chief investigator at the Francis Crick Institute and a consultant neurologist at UCLH, said in the statement.
COVID-19 vaccine booster provides good antibody protection against Omicron. EurekAlert. News release. January 19, 2022. Accessed January 20, 2022. https://www.eurekalert.org/news-releases/940572