By Jason Gale December 3, 2021
Urgent studies to understand how effective Covid vaccines are against omicron have begun in a global collaboration that may yield answers in a few days, a World Health Health Organization scientist said.
Some 450 researchers around the world have begun work to isolate the highly mutated variant from patient specimens, grow it in the lab, verify its genomic sequence, and establish methods to test it in blood-plasma samples, said Ana-Maria Henao-Restrepo, who co-leads the WHO’s research and development blueprint for vaccines and innovations during outbreaks and pandemics.
“They hope that this will happen within days, but I think we should not put pressure that it should happen within three days — we should say it will happen within the next two weeks,” she said in a Zoom interview from Geneva Wednesday.
The rapid spread in South Africa of the worrisome variant has raised concern that the immune protection generated by vaccination or a previous bout of Covid is insufficient to stop reinfections or stem a fresh wave of cases and hospitalizations. The WHO warned on Sunday omicron could fuel surges with “severe consequences” amid signs that it makes the coronavirus more transmissible.
The work involves testing blood plasma from people who have recovered from a SARS-CoV-2 infection or been immunized with different Covid vaccines to gauge the concentration of antibodies needed to neutralize, or block, the virus. The results will help determine whether or not existing Covid vaccines need to be altered to protect against omicron.
“I expect there to be public data on neutralizing antibodies in less than two weeks,” said Shane Crotty, a professor in the Center for Infectious Disease and Vaccine Research at San Diego’s La Jolla Institute for Immunology. A lab run by the institute’s Alessandro Sette is assessing the T cell response to omicron, he said.
Any decision to change vaccine composition would require careful consideration, especially since delta is currently the main driver behind the Covid epidemics and existing vaccines provide a sufficient shield against it, Henao-Restrepo said. Even still, some vaccine makers have begun preparing tweaked versions.
“We welcome that because they will help us to prepare,” she said. “WHO is contacting each of the vaccine manufacturers and requesting from them information on their current plans to modify their vaccines, if they have any preliminary data, and the time line for the scaling up and implementation of the modifications.”
WHO is looking to play a coordinating role, as it does with seasonal influenza vaccines, to ensure any decision to change the immunizations is based on the recommendations of global experts, manufacturers and regulatory authorities, Henao-Restrepo said.
“In the best interest of the planet, a coordinated approach in the decision-making process is the best,” she said.
Some experts thought an updated shot would be necessary to corral the beta variant because of its ability to evade protection. But that strain never became dominant globally and the current vaccinations have been shown to significantly avert severe infection and deaths.
Although antibody levels decline in the months after an infection or vaccination, their ability to neutralize coronavirus variants has been show to improve over time. What’s more, studies have found that a third dose some six months after the second can bolster levels of these better-quality antibodies, making boosters an important weapon to fight omicron.
“I don’t think we should get all excited about some sort of omicron-specific vaccine because, so far, that’s not what we’ve seen as being the best thing to fight against it,” said Deborah Cromer, head of the infection epidemiology and policy analytics group of the University of New South Wales’ Kirby Institute in Sydney. “We’ve seen that the wild-type vaccines are fine and are doing a good job.”
The omicron variant has 30 or more changes in the spike protein, half of which are in the area that binds to the enzyme that the coronavirus targets to enter cells and cause an infection. Mutations there can make the pathogen less recognizable to antibodies.
It’s possible SARS-CoV-2 will eventually accumulate enough mutations to escape antibody detection completely and warrant the need for booster shots with a different formulation, said Jonathan Abraham, an assistant professor of microbiology in the Blavatnik Institute at Harvard Medical School and an infectious disease specialist at Boston’s Brigham and Women’s Hospital. “But at this point, there’s no evidence to say that the virus has found a perfect solution that allows escape.”
Abraham and colleagues studied mocked-up coronavirus versions, called pseudoviruses, with mutations in the pathogen’s receptor binding domain to test the effectiveness of vaccine-induced and therapeutic antibodies. Resistance was detected when seven mutations were found, his research published Thursday in the journal Science found.
It’s still too early to say whether omicron — with 15 mutations in the receptor binding domain — will require vaccines to be updated, Abraham said. “But all evidence is pointing in that direction, meaning that if we were asking ourselves that question with beta, we should definitely be asking ourselves that question even more urgently with omicron.”