In a press release on June 30, 2020 the US FDA issued guidance to manufacturers “help facilitate the timely development of safe and effective vaccines to prevent COVID-19” in order to win regulatory approval. [7]
“The guidance also discusses the importance of ensuring that the sizes of clinical trials are large enough to demonstrate the safety and effectiveness of a vaccine. It conveys that the FDA would expect that a COVID-19 vaccine would prevent disease or decrease its severity in at least 50% of people who are vaccinated.” Also the vaccine companies would be required to monitor the vaccine’s performance after approval for any emerging safety problems. [1, 2, 3]
“If you had a 60 or 70 percent effective vaccine and everybody took it, you might actually be reaching toward herd immunity and potentially then dampen down this pandemic,” Dr George Poland of the Mayo Clinic said on Nov 3, 2020.
As a comparison the flu vaccine effectiveness which “can vary widely from year to year has been anywhere from 20% to 60% effective over the last decade.
According to GlobalData on April 9, 2020 the WHO sets two vaccine success benchmarks for vaccines. “Preferably, the vaccine should have at least a 70% efficacy on a population basis with durability for at least a year for reactive use in an outbreak and/or protection for those with a high ongoing risk. The lower success bar is about 50% efficacy with at least a six-month durability”. [4]
They go on to state: “The 50% success bar, while low, is acceptable, as it would likely be enough to ease the pressure on frontline healthcare resources but it may not be high enough to reach herd immunity.”[6]
FDA commissioner Dr Stephen Hahn in a JAMA interview on July 30, 2020, stated “We all want a vaccine tomorrow. That’s unrealistic. And we all want a vaccine that’s 100% effective. Again, unrealistic,” Hahn said “we said 50%, and the reason was because we felt that that was a reasonable floor given the pandemic.” [5]
A couple of days earlier, Dr Anthony Fauci said he would like 60% meaning on average the vaccine reduces a person’s risk of SARS-CoV-2 infection by 60%.