Canada needs a clear booster shot plan

THE BENEFITS OF BOOSTERS IS DRIVEN BY SCIENTIFIC DATA. — RAKOWSKI

Vaccination has been an essential public health measure that has helped to greatly reduce the harm of being exposed to COVID-19. It has allowed us to reopen our economy, facilitate safer social interaction and avoid death and disability. It has also led to a small but vocal protest movement that rejects the benefits of vaccination and promotes falsehoods about its risks. Anti-vaxxers have also suggested that the need for booster shots is evidence of the vaccine’s inefficacy. This portrays a fundamental misunderstanding of how effective the existing vaccines are and why boosters are necessary.

Vaccines provide protection from infection by stimulating antibodies that bind to the spike protein of the virus and block entry into cells, thus restricting viral replication. The amount of antibody production and its rate of decay can be measured by a simple blood test. The additional protective cellular immunity from cells that can remember and fight the virus is harder to measure, as is the residual level of protection as immunity wanes.

The MRNA vaccines, which are now exclusively used in Canada, were about 95 per cent effective at protecting against the original SARS-COV-2 strain when compared to the unvaccinated and about 88 per cent effective against the Alpha variant. The lower efficacy rate is due to mutations in the spike protein of the virus, which meant that antibodies developed to target the original viral spike protein were not as specific and thus not quite as effective.

The spread of other variant of concern with more spike protein mutations, primarily the much more contagious Delta variant, meant higher antibody levels were needed to fight the virus and prevent it from causing serious infection. The current concern about the Omicron variant originating in Southern Africa is that its high number of mutations may make it both more transmissible and possibly more resistant to the antibodies produced by the current vaccines.

It is not surprising that the combination of antibodies produced being less effective, and their natural decay over time, has led to increasing rates of infection in fully vaccinated people. As expected, serious breakthrough infections are occurring most commonly in higher-risk people with initial low antibody production or higher rates of antibody decay.

At some point, we will likely have vaccines that specifically target the mutated spike proteins of the new variants. But for now, the best we can do is offer third doses to as many people as possible, in order to boost immunity among the population.

The benefits of boosters is driven by scientific data. Israel, which has seen waning immunity due to an early and speedy mass vaccination campaign and was hit hard by the Delta variant, has been far more aggressive in giving booster shots.

An Israeli Health Ministry study found that the Pfizer vaccine’s ability to prevent infection had been reduced to 39 per cent by mid-july. Protection against severe illness, a key benefit, dropped to 81 per cent, from an earlier 97 per cent.

Yet a study conducted by Maccabi Healthcare Services showed that about 150,000 people who received a third shot had about an 85 per cent reduction in infection compared to a matched group that only received two doses, thus restoring high immunity within a week of the booster shot.

Based in part on this data, Israel has been offering boosters to anyone who received their second shot more than five months ago. The United States and the United Kingdom rapidly followed suit. Canada continues to lag behind, despite the fact boosters have safely been administered to tens of millions of people around the world.

Understandably, there is a great deal of COVID-19 fatigue and frustration. You don’t have to be an anti-vaxxer to dislike mask mandates and other limits on workplaces and social gatherings. There is fear that we will need to be vaccinated endlessly to deal with current and future variants of concern.

Israel has already restricted entry to those who received their second shot less than six months ago. Other countries may follow this path if cases rise dramatically due to more worrisome variants.

We don’t yet know whether the Omicron variant will supplant Delta and be the predominant cause of infection. Testing the blood sera of three groups of people — those previously infected, those with two vaccine doses and those who have received boosters — will help inform us as to the risk of Omicron piercing natural or induced antibody protection. This data should be available within a couple weeks.

Using the original vaccine as a booster offers sufficient protection against the Delta variant and will hopefully protect against Omicron, as well. If not, Pfizer and Moderna have announced that a new booster targeted to the Omicron mutations would likely take about three months to develop.

What we need from our federal and provincial governments is an acknowledgment of the risk of waning immunity, data on the incidence of new variants, information on the procurement of adequate amounts of booster shots and a plan to efficiently administer them.

Hopefully, if needed on an ongoing basis, boosters will be targeted to the willing and most vulnerable, without the requirement for a mandate.

For now, like it or not, we need them. I hope that this time, we can stay ahead of the curve rather than getting swamped by a wave of predictable and avoidable illnesses.

THERE IS FEAR THAT WE WILL NEED TO BE VACCINATED ENDLESSLY.