How well a vaccine works — or its efficacy — ranges broadly for current vaccines. The seasonal flu vaccine, for instance, is about 40% to 60% effective each year, according to CDC data. The measles, mumps, and rubella vaccine, which is often given to children in two doses, is about 97% effective, according to the CDC.
A less-effective flu shot can still help prevent illness, public health officials say. For example, in the 2018-19 flu season, the vaccine was only 29% effective. Still, the CDC estimates that vaccinating only half of all Americans prevented 4.4 million cases of the flu, 58,000 hospitalizations, and 3,500 deaths.
It is not yet known what those numbers might look like with a COVID vaccine that’s 50% effective
Tamera Coyne-Beasley, MD, says doctors have to do better at telling their patients how important the vaccine is.
“We have to stop talking about numbers, because numbers aren’t really tangible to people,” said Coyne-Beasley, a professor of pediatrics and internal medicine at the University of Alabama at Birmingham, during an interview with Whyte on WebMD’s “Coronavirus in Context” video series.
She also researches vaccines and has served on the Advisory Committee on Immunization Practices. “We have to talk about stories. We want to talk about the lives that are saved,” she said.
Researchers across the world are working on more than 170 potential coronavirus vaccines, according to the World Health Organization, with 142 candidates in preclinical evaluations and 31 in clinical trials. Seven are in phase III trials, or the final stage that tests how safe and effective a vaccine will be.
In the U.S., the federal government has provided billions of dollars through Operation Warp Speed to six companies working on a vaccine. The financial aid allows the companies to ramp up manufacturing so a vaccine can be produced and distributed quickly once approved. Three of the candidates are now in phase III trials.
Public health officials have said the population needs to reach a 70% level of herd immunity — meaning people who have either already been infected or have immunity from a vaccine — for the pandemic to end.