Former FDA Commissioner Scott Gottlieb has a rough estimate for the number of vaccinated people to reach herd immunity for COVID-19.
Because about 20% of people may have already been infected by the time a COVID-19 vaccine is launched, “we’d need to get perhaps 40% utilization to achieve herd immunity,” he tweeted Tuesday.
How does that stand up to adoption of vaccines we're all familiar with? It's about on par with seasonal flu shots, which are administered to around 45.4% of the eligible U.S. population each year. Shingles vaccine, though, has around 34.9% utilization in the U.S.
When we get a covid19 vaccine, one question is whether enough consumers will use it. Since 20% or more may have been infected by that time, we'd need to get perhaps 40% utilization to achieve herd immunity. These are rates of uptake of other vaccines among indicated populations. pic.twitter.com/oLzD8yuGu1— Scott Gottlieb, MD (@ScottGottliebMD) May 26, 2020
Gottlieb’s herd immunity total of 60% comes roughly close to the 70% overall immunity suggested by two epidemiologists at the Johns Hopkins Bloomberg School of Public Health.
For herd immunity to work, a large number of people need to be immune to an infectious disease, ideally through vaccination, thereby providing indirect protection to those not immune.
But as one person commented under Gottlieb's tweet, convincing people to be immunized “[m]ust address genuine concerns re a vaccine rapidly developed which has not gone through customary trials. You’ll see many people refuse to be vaccinated.”
Governments around the world are rooting for early adoption of a vaccine. And as Gottlieb himself recently wrote in a Wall Street Journal article titled "America Needs to Win the Coronavirus Vaccine Race," "The first country to the finish line will be first to restore its economy and global influence."
But a 2009 study conducted during the H1N1 pandemic found only 8% of surveyed people were definitely willing take a theoretical H1N1 vaccine the FDA authorized for emergency use but didn't formally approve. Given that the FDA has already granted emergency authorizations to COVID-19 diagnostics and therapeutics, the agency will likely also consider such a path for a vaccine.
Reaching 40% vaccination rate means the U.S. will need 131 million doses of single-dose shots, and more vials will be required for multidose vaccines. As for the entire world of 7.8 billion people, the demand reaches 3.1 billion.
At least vaccine manufacturers appear ready to deliver on the capacity front if their shots prove efficacious. AstraZeneca recently won a $1.2 billion award from the Department of Health and Human Services’ Biomedical Advanced Research and Development Authority to help develop and produce the University of Oxford’s vaccine. The British drugmaker said it has agreed to initially supply at least 400 million doses of the shot and secured total manufacturing capacity for one billion doses.
Moderna signed a deal with Lonza to accelerate manufacturing of its mRNA candidate, mRNA-1273. Under that 10-year agreement, the companies aim to make up to a billion doses per year.
Sanofi, in collaboration with GlaxoSmithKline, recently said it has capacity to make about 100 million to 600 million doses and that it has a plan to expand to 1 billion doses per year.
All major vaccine developers, including Pfizer and partner BioNTech, Johnson & Johnson and most recently Merck & Co., have joined the COVID-19 vaccine development efforts that could further expand the offering to cover demand.