July 19, 2022 -- Despite the evolution of the SARS-CoV-2 pandemic coronavirus, a new laboratory study conducted by a team of international researchers suggests current vaccine boosters may elicit sufficient immune protection against severe omicron-induced COVID-19 disease.
The study's results, published as an early release paper on July 19 in the journal Science, compared omicron immunity from primary vaccines and boosters for seven COVID-19 vaccines. What researchers found was that a booster dose, regardless of the type of vaccine, brings neutralizing antibodies against all the omicron subvariants to appreciable levels.
"Administration of a homologous or heterologous booster based on the Wuhan-Hu-1 spike sequence markedly increased neutralizing antibody titers and breadth against BA.1, BA.2, BA.2.12.1, and BA.4/5 across all vaccines evaluated," the authors of the paper state. "Our data suggest that although omicron sublineages evade polyclonal neutralizing antibody responses elicited by primary vaccine series, vaccine boosters may provide sufficient protection against omicron-induced severe disease."
The results are consistent with other research finding that a third COVID-19 vaccine dose expands existing memory B cells specific for the spike protein of the SARS-CoV-2 pandemic coronavirus, as well as inducing new ones, leading to production of antibodies with enhanced potency against the omicron subvariants.
While scientists are still learning about omicron BA.5, the COVID-19 variant is now the most common strain across the U.S., according to the Centers for Disease Control and Prevention. What is known about the BA.5 variant is that it is hypercontagious and is contributing to increases in hospitalizations and intensive care unit (ICU) admissions.
A study published earlier this month in Nature found the BA.5 variant was four times more resistant to messenger RNA vaccines than earlier strains of omicron and more likely to lead to vaccine breakthrough infections. That study observed the omicron lineage of SARS-CoV-2 continues to evolve with subvariants that are not only more transmissible but also more evasive to antibodies.
"Whether you've been vaccinated, whether you've been previously infected, whether you've been previously infected and vaccinated, you have very little protection against BA.5 in terms of getting infected or having mild to moderate infection. You have good protection against dying, being hospitalized, or ending up on a ventilator," warned Dr. Gregory Poland, head of the Mayo Clinic's Vaccine Research Group, in a July 14 statement.
Nonetheless, the Science paper makes the case that COVID-19 boosters offset some omicron immune evasion tactics. "The marked improvement in plasma neutralizing activity for subjects that received a booster dose over those that did not highlights the importance of vaccine boosters for eliciting potent neutralizing antibody responses against omicron sublineages," researchers said.
However, new clinical trial data published July 19 in Cell Reports Medicine showed that while COVID-19 booster vaccinations in adults elicit high levels of neutralizing antibodies against the omicron variant, antibody levels decrease substantially within three months.