Israel has begun offering third doses of the Pfizer vaccine to its at-risk, vaccinated population. The reason? Immunity in some vaccinated people is decreasing faster than in others, with herd immunity unlikely even after 90% of a population is fully vaccinated.
The heightened transmissibility of COVID-19's Delta variant combined with gaps in the vaccines’ ability to fully prevent infection means variants will continue to be passed on from person to person. In Australia, this could have far-reaching implications when our borders reopen, with natural immunity low among the general population.
While herd immunity might be off the table for at least another year, booster doses of Pfizer could get us closer to that magic number -- though Australia has already fallen behind Europe and North America in securing more supplies of the Pfizer vaccine.