Looking Ahead To A COVID Fall/Winter Renewal

"The good news is that the epitopes [parts of the spike protein] recognized by T-cells, which are critical in protection against severe disease, have remained relatively well conserved."

"So, even if you were only vaccinated with the original ancestral strain, protection against severe disease in those who are relatively young and healthy appears to be holding up."

"I believe we should stop trying to prevent all symptomatic infections in healthy, young people by boosting them with vaccines containing mRNA strains that might disappear a few months later."

Dr. Paul Offit, member, U.S. Food and Drug Administration vaccine advisory committee

"My worry is that we will have very low uptake of vaccines in the fall."

"[SARS-Cov-2] has evolved dramatically in the last three years. The mutations that have emerged in many ways makes the virus nearly unrecognizable to the immune system, and to the protections we had in place against the original variant."

Dr. Fahad Razak, internist, Unity Health, Toronto, past scientific director Ontario COVID-19 scientific advisory table

Moderna's bivalent COVID-19 vaccine was among those being offered by health-care workers at a vaccination site in Brampton, Ont., on Oct. 11, 2022. (Turgut Yeter/CBC)

 

Dr. Matthew Tunnis, immunologist and executive secretary to the National Advisory Committee on Immunization (NACI) speaks of diminishing vaccine uptake -- that the public with respect to COVID vaccines may be approaching "sort of an acceptability settling point". And to address the issue, additional "promotional activities" and communication strategies may be required in the interests of being able "to explain and rationalize what value the vaccine program can bring".

Outside Canada, some experts in the field question the requirement for yet another expansive round of boosting. A member of the U.S. Food and Drug Administration's vaccine advisory committee wrote "I believe we should stop trying to prevent all symptomatic infections in healthy, young people..." in the New England Journal of Medicine, earlier in the year. Dr. Offit feels that boosters are "best reserved" for  high-risk groups like the elderly and the immunocompromised.

Human T-cell defence, cellular immunity, appears to be coping with SARS-CoV-2 mutations, he feels, to the point that the level of neutralizing antibodies fail to tell the entire story. A sizable proportion of the Canadian population has given signals of being booster-weary, just as have populations elsewhere in the world. At least two doses of a COVID vaccine covers 83 percent of the population, over half, 51.5 percent, are "fully vaccinated" with a third dose, according to the COVID-19 Vaccine Tracker.

On the other hand, a mere 26 percent of Canadians from age five and older received one of the bivalent vaccines rolled out last September; a 50-50 mix containing some of the original strain along with the then-rapidly spreading Omicron subvariants BA.4 and BA.5. If someone hasn't been vaccinated as of today, Dr. Razak cautioned, "don't go out and get vaccinated now, unless you have a specific, high-risk reason to do so". Wait until updated shots are available, come fall.

Now under review by Health Canada, the latest formulations entirely dropped the original strain which is considered no longer in circulation. The target is newer Omicron subvariants, specifically the dominant currently-circulating stain XBB. "Individuals vaccinated with the updated formulation are expected to benefit from a better immune response against these variants in comparison to current vaccines", the latest advice from NACI.

Come fall, for those previously vaccinated against COVID-19, NACI recommends a dose of the new vaccines for people in any age groups who are ultimately authorized to receive them, at least six months from their previous COVID vaccine or identified SARS-CoV-2 infection. Immunity from even hybrid protection; vaccination plus infections; wanes with time.

COVID is no longer the unpredictable, severe respiratory disease it once presented as, with overwhelming COVID pneumonias where people rapidly deteriorated. requiring high levels of oxygen, and many of these patients dying..."are very, very rare now", assured Dr. Razak.

A pharmacist administers a coronavirus booster dosage at a vaccination clinic in Lawrence, Mass. (Charles Krupa/AP)

"[The best way to protect the vulnerable] is to have everyone boosted."

"It's imperative we get vaccinated so that during cold and flu season we don't see the same disruptions to health care that we saw last year."

"[Part of the problem is calling them] boosters -- suggesting a] top-up. Like a yearly flu shot] you can't reasonably expect to be protected from symptomatic infections or hospitalization unless you are recently vaccinated with a matched vaccine."

Dawn Bowdish, immunologist, McMaster University