close
Canadian army

COVID-19 vaccine targeting multiple variants needed: expert

OTTAWA – Health Canada’s chief medical adviser says variant-specific vaccines can be approved faster than general vaccines first issued to fight COVID-19, but one targeting the Omicron strain likely won’t be ready in time to help with the last wave.

Dr Supriya Sharma said what is really needed are vaccines that can potentially stop more than one variant at a time, including those to come.

Omicron became the dominant variant in Canada in just over two weeks, and the Public Health Agency of Canada said Friday that it will now be responsible for more than 90% of all COVID-19 cases.

Studies suggest that two doses of the existing mRNA vaccines from Pfizer-BioNTech and Moderna are not effective in preventing Omicron infection.

However, several studies suggest that vaccines are excellent for keeping symptoms mild, preventing hospitalizations, shortening stays and reducing the standard of care for those admitted to hospital. Fewer vaccinated Omicron patients, for example, require mechanical ventilation.

Both Pfizer and Moderna are working on new versions of their vaccines that specifically target the Omicron variant.

Moderna hopes to have its product tested early this year. Pfizer said it could have 100 million doses ready as early as March, and Canada has contracts for boosters from both companies that would also include vaccines for variants.

But Sharma said even with the accelerated vaccine variant review process, it’s “probably not” fast enough.

“By then, from what we know of the Omicron wave, it may well be over,” she said. “And then the question is always, ‘is there another variant coming up?’

The solution, she said, likely lies in vaccines that can target more than one variant at a time.

The World Health Organization’s COVID-19 vaccine technical committee said the same on Jan. 11, noting that Omicron is the fifth variant of concern in two years and “probably won’t be the last.”

Booster shots that increase antibody development have become the immediate response to Omicron for many governments, including Canada.

Dr. Srinivas Murthy, a British Columbia pediatrician and co-chair of the WHO’s clinical research committee on COVID-19, told The Canadian Press that boosters are not a viable long-term option.

“Boosting your exit from a pandemic is inevitably going to shoot you in the foot in the sense that you’re going to have a future variant that’s going to emerge that’s going to cause problems,” he said. “He’s going to escape your shots, and then you’re going to have to figure it out.”

Omicron does not entirely avoid existing vaccines, but a future variant might, he said. Much of the problem stems from the fact that the original vaccines train the body’s immune system to recognize what’s called the spike protein found on the surface of a virus, and that spike protein undergoes a significant mutation. .

Think of the mutated spike protein as a bit of a disguise that makes it harder for the immune system to recognize the virus and mount a defense to kill it.

Omicron has over 50 mutations, and at least 36 are on the spike protein.

Multivalent vaccines that use the spike protein of more than one variant, or that target the genetic components of a virus rather than the spike protein, may be the ones that could offer protection against both this pandemic and against the next new emerging coronavirus.

“It’s a pan-coronavirus, where it’s looking at big, broad neutralizing responses and you don’t have to update it every season and so on,” Murthy said. “It’s been the holy grail of influenza vaccinology for several decades. We haven’t gotten there yet, because influenza is a bit tricky, but we think it’s doable for coronavirus, in particular.”

The US military has a version heading into phase 2 trials that can attach several advanced proteins. A vaccine with the specific spike proteins of the five COVID-19 variants of concern would likely be more effective, even against future variants, as they all share some of the same mutations and what one might miss another can catch. .

Moderna is working on multivalent vaccine trials using combinations of the original virus’ spike proteins and one of the variants, or two of the variants together. It is unclear when they would be ready for use.

Sharma said that while vaccines don’t work as well against the variants as they do against the original virus, to her “they’re still miraculous.”

“To have a vaccine that was developed so quickly, that still has, through multiple ΓǪ variants with boosters, up to 70, 80% efficacy against serious illnesses, conditions, hospitalizations and deaths” , she said. “It’s miraculous for a new vaccine against a new virus.”

This report from The Canadian Press was first published on January 16, 2022.

Tags : long term
Rodney N.

The author Rodney N.