A report by Public Health Ontario says that at least 90 percent vaccine coverage against COVID-19 for the entire population is needed to achieve herd immunity and that vaccines will need to be given to young children.
Currently, children under the age of 12 years old are ineligible to get a shot, which makes getting to such a high percentage difficult or impossible to obtain, the report indicates.
The report, released on Monday, said the Delta variant is more transmissible, causes more severe disease and reduces the effectiveness of a single vaccine dose compared with other strains. And Delta is now the dominant variant of COVID-19 in the province.
“As a result, the level of vaccine coverage needed for ‘herd immunity’ is now estimated to be at least 90% of the population, and over 100% of the vaccine eligible population,” the report read.
Dr. Peter Yuni, scientific director for Ontario’s COVID-19 science table, previously told Global News earlier this week that some sort of restriction will be required, in addition to a continued vaccine effort, until children under the age of 12 can get a shot.
The report also called the fall scenario “complex” due to a number of factors. The report cited factors such as how Ontarians will behave once the restrictions are fully lifted and when young children will be eligible for vaccines.
It also mentioned that low global vaccine coverage paired with increasing national and international travel to and from Ontario will also be challenging for herd immunity to be obtained.
Dr. Kieran Moore, Ontario’s chief medical officer of health, also said at his weekly briefing on Tuesday that he would like to see 90 percent of the eligible population be fully immunized.
“We need to get our numbers higher, above 90 percent, to slow this virus down, to limit the community effect and then we’ll see the benefits of decreasing hospitalizations, decreasing use of the intensive care unit,” Dr. Moore said.
The report also said Ontario’s three-step reopening plan was originally based on the Alpha variant (B.1.1.7). That plan required that 75 percent of the eligible population be fully vaccinated, which Ontario has achieved. As well, all of the 34 local public health units must have at least 70 percent of their eligible population fully vaccinated to move past Step 3; all units except Haldimand-Norfolk, which sits at 69 percent, have met that threshold.
However, the report said with the Delta variant, those thresholds must be higher.
“It is important to note that at the time of writing, children under 12 years of age are expected to still be ineligible for vaccination in the early fall, with the potential for widespread outbreaks given the significantly increased transmissibility of Delta,” the report read.
“This would be expected to have a significant impact in daycare, school and before/after school settings,” the report continued. “At the individual-level and within relevant populations, children under 12 years of age will still be at risk of infection and for spreading to older individuals who are not fully vaccinated in the community and are at increased risk of severe outcomes.”
The report also indicated that if there is a surge in cases, a small percentage of children with severe outcomes could become a significant issue.
Herd immunity is when enough people have protection against the disease — through either being vaccinated or by catching it, recovering and developing antibodies — that even if the disease gets reintroduced, it won’t lead to outbreaks because most people are protected.
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