Q: What are COVID-19 breakthrough cases? How many are we experiencing? Can I still get infected if I am vaccinated? Why should I get a vaccine if I can still get infected?
“Breakthrough cases” refer to cases of COVID-19 in fully vaccinated individuals.
York Region medical officer of health Dr. Karim Kurji said about 13 per cent of new cases in the past seven days, as of Aug. 19, have been breakthrough cases, but that figure has shifted between 10 to 24 per cent. The vast majority of new COVID-19 cases are still in unvaccinated individuals.
Kurji said the primary purpose of vaccinations is to prevent serious illnesses, hospitalizations, and deaths from the disease.
“Fully vaccinated individuals are not entering the hospitals, and are not developing serious illness, and certainly when we look at the deaths, these are occurring in unvaccinated individuals,” Kurji said. “The vaccine is doing what it is intended to do quite well.”
No vaccine is 100 per cent effective at preventing an illness, but they do reduce the likelihood of becoming ill, and the severity of symptoms.
According to the National Advisory Committee on Immunization, emerging data indicates the Pfizer vaccine is 87.9 per cent effective against symptomatic illness of the delta variant after two doses, and 96 per cent effective at preventing hospitalization after two doses.
AstraZeneca vaccines are less effective against symptomatic illness from the delta — about 59.8 per cent after two doses, according to emerging data. But they are still 92 per cent effective at preventing hospitalization after two doses.
Data for the Moderna vaccine is not included in the latest National Advisory Committee on Immunization publication.
Public Health Ontario released data July 23 indicating two doses of Moderna or Pfizer vaccine offer similarly high efficacy against the delta variant as other strains of COVID-19.
Q: Can I still infect others if I am vaccinated?
If you catch COVID-19 while vaccinated, Kurji said it's possibile to infect others. Regardless of vaccination status, anyone with symptoms should get tested, and isolate if you are confirmed to have COVID-19.
Kurji said only about two-thirds of the total York Region population is vaccinated, including children under 12 who cannot get vaccinated yet. He added caution and more vaccinations are needed.
“We have about 400,000 people, including children, who are potentially unprotected. Given that we have an aggressive delta variant, it can extract quite a lot of damage," Kurji said. “That is what we have to try and prevent.”
The World Health Organization indicates that vaccines offer some protection from transmission. Its director of the immunization, vaccines and biologicals, Katherine O’Brien, said having a vaccine makes you less likely to spread the disease, given you are less likely to catch it in the first place, and are quicker to shed it.
Q: As a vaccinated individual, how concerned should I be about getting the virus from an unvaccinated person?
“Those are very valid concerns. In general, the likelihood of acquiring infection from unvaccinated individuals is probably greater than acquiring it from vaccinated individuals,” Kurji said. “However, when one is vaccinated, one still has to continue taking all those precautions: physical distancing, masking when indoors and washing hands.”
Q: How long does a COVID-19 vaccine protect me?
According to the National Advisory Committee on Immunization, the long-term efficacy of protection from a COVID-19 vaccination is unknown, as only short-term data is available.
Israel announced in July that it would offer booster shots to elderly residents who received a vaccine in January, with preliminary studies indicating protection against serious illness was dropping over time. Ontario announced this week it would start offering booster shots to vulnerable populations.
Although most mass vaccination centres are closing in York Region this month, Kurji said the region is planning for mass vaccinations again, if the province directs it.
