Waning immunity not unusual says Bocking, as health unit urges third-dose booster shots

By William McGinn

Outbreak at correction centre driving local COVID numbers up
“More research is being done to investigate Omicron’s severity of illness, transmissibility and impact on existing vaccine effectiveness."

As booster shot eligibility is now lowered to 50, the local health unit’s medical officer of health, Dr. Natalie Bocking, says it’s not a surprise another shot is now needed to fight against COVID-19.

According to the Haliburton Kawartha Pine Ridge District Health Unit’s COVID-19 dashboard, since July 1 and as of Dec. 14, there have been 497 confirmed COVID-19 cases in the region. Nearly 59 per cent have been unvaccinated or have unknown vaccination status, but 27 per cent of the cases have come from those fully vaccinated (meaning two doses.)  Ten per cent were partially vaccinated, and the rest were not yet protected from their vaccination due to the timing of their vaccine acquirement.

Bocking said emerging evidence shows COVID-19 vaccine effectiveness may decrease over time, referred to as waning immunity, and a booster dose can help restore and maintain protection.

“Getting a booster dose of any vaccine is not unusual,” she explained. “Many children’s vaccines include boosters given at different ages. There is also the tetanus vaccine, which requires a booster shot every 10 years. An even better example is the influenza vaccine, which is recommended every year to provide protection against the flu, whose strains can change annually.”

“Going forward,” said Bocking, “the same thing may apply that we will need an annual COVID-19 vaccine booster.”

According to news reports, anticipating that annual COVID-19 boosters may be needed in the future, some drug companies, including Moderna and Novavax, are already working to develop a combination flu/COVID vaccine.

When asked if there is any difference between this booster shot and the previous two, Bocking said Pfizer’s booster dose “is identical to the vaccine given for the first two doses (30 mcg). Moderna’s COVID-19 booster is a half dose of its regular vaccine (50 mcg) for people under the age of 70, and a full dose (100 mcg) for people aged 70 and over. Both are now available as boosters in Ontario.”

“We do know that ‘breakthrough’ cases can occur,” said Bocking, “in which people who are fully vaccinated can still get COVID-19. Typically, fully vaccinated individuals who get sick with COVID-19 tend to suffer less serious symptoms and have a much lower risk of being hospitalized or ending up in the ICU.”

Stuart Oakley, corporate communications and marketing manager for all Caressant Care homes,

Oakley shared how one of the Caressant Cares had some recent breakthrough cases in St Thomas, “and the difference is that although some are testing positive, by and large they’re either asymptomatic or very mild symptoms.”

Following guidelines from the Ministry of Long-Term Care, Oakley said all Caressant Care staff must be double vaccinated and have been given the option for a third dose, and “having the resident staff vaccinated has really made a difference in terms of people actually being sick. It’s different from when we were seeing outbreaks before vaccinations.”

“The vaccines are our best defense but they’re not 100 per cent foolproof,” said Oakley. We’re biological beings and this is a virus, so we do what we can and that’s the best tool we have to fight it. But that’s why we can’t let our guard down.”

According to Ontario’s COVID-19 Science Advisory Table, unvaccinated people have a six-time higher risk of symptomatic COVID-19 disease, and an 11-time higher risk of being in the hospital. They also are 26 more times likely to end up in the ICU compared to someone who is fully vaccinated. 

“More research is being done to investigate Omicron’s severity of illness, transmissibility and impact on existing COVID-19 vaccine effectiveness,” said Bocking, “and this information will be invaluable to see what…changes may be needed to the current mRNA vaccines (Pfizer and Moderna) to provide better protection against the Omicron variant.”

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