Question: What does the new data from Israel mean for booster shots?  Will we need booster shots soon?

Answer: We still don’t know if/when we would need booster shots and/or if only certain subsets of the population would need booster shots.  We’ll know more with more time and research. I am aware of at least 3 pieces of new research published within the last week, which shed some light:

1. New data from Israel show Pfizer’s effectiveness against infection is potentially waning: Israel, having achieved one of the world’s highest vaccination coverage rates, has been closely studying vaccine effectiveness in the general population.  A few days ago, the government released preliminary data on vaccine effectiveness over time, which indicated that effectiveness may have waned (Figure 1).  This could be due to a number of factors, including: a) small sample size limiting ability to extrapolate to broader population (e.g. the data are not robust enough to draw conclusions); b) Reduced vaccine effectiveness in response to the Delta variant; c) Diminished vaccine effectiveness over time; d) Reduction in use of other public health interventions.  I wouldn’t put too much weight on these data due to the small sample size and need for more nuanced analysis.  And if you’re feeling disheartened, please note that the data are very positive when it comes to Pfizer’s continued, steadfast ability to prevent severe disease outcomes (like hospitalization or death) (Figure 2).   
2. New data from Public Health England show that the risk of reinfection is higher in association with the Delta variant: Public Health England recently examined the risk of reinfection between Alpha and Delta variants, running an analysis that accounted for a number of background characteristics.  During the 11-week study period, there were 83,197 people who tested positive, of whom 980 (1.2%) were possible reinfections (e.g. had a previous positive test result 90+ days earlier). Researchers found that the odds of reinfection with the Delta variant were “1.46 (95% CI 1.03 to 2.05) compared to the Alpha variant. The risk of reinfection was not elevated for Delta if the primary infection was <180 days (adjusted odds ratio = 0.79, 95% CI 0.49 to1.28) but was higher for those with a prior infection ≥180 days earlier (adjusted odds ratio = 2.37, 95%CI 1.43 to 3.93).”  If natural immunity wanes over time, then this could have implications for vaccine-derived immunity too (but even that is quite a logic leap).  Again, we just don’t know enough yet to actually know!
3. New research published in JAMA indicates a 3rd dose could be warranted for immuno-compromised individuals. Researchers examined the antibody responses of kidney transplant recipients who did not respond to 2 doses and received a third dose of Moderna.  They found that the 3rd dose induced an immune response in 49% of kidney transplant recipients who had not responded after 2 doses, indicating that a 3rd dose may be beneficial for organ transplant recipients (and if one were to extrapolate, a 3rd dose would perhaps be beneficial to other immuno-compromised individuals as well). 

Figure 1. Breakthrough Rate by Age, Month of Vaccination (from Israel)

Figure 2. Vaccine Effectiveness by Outcome, Month of Vaccination(from Israel)