The leading coronavirus vaccines are shaping up to be on par with some of the most effective vaccines in medicine.
Why it matters: Vaccines with efficacy rates of about 95% — which both Pfizer and Moderna say they've achieved — will be more powerful weapons against the coronavirus than many experts had anticipated.
Flashback: The Food and Drug Administration initially set the bar for a COVID-19 vaccine at 50% efficacy, roughly in line with the seasonal flu vaccine.
- Some scientists had hoped, in a best-case scenario, it might be as much as 70% effective.
- “We don’t know yet what the efficacy might be. We don’t know if it will be 50% or 60%. I’d like it to be 75% or more,” the NIH's Anthony Fauci said in August.
But coming in closer to 95% would put Pfizer and Moderna's vaccines more in line with the highly effective inoculations against measles, mumps and rubella.
- Like the MMR and polio vaccines, both prospective COVID-19 products would require two shots to reach that level of efficacy.
- The third leading contender, being developed by AstraZeneca and Oxford University, would also require two shots. Johnson & Johnson is testing both a single-dose and a two-dose vaccine in simultaneous phase 3 trials.
Yes, but: There's still a lot we don't know about these vaccines, including how well they're likely to work among various demographic groups, and how long the immunity they confer will last.