Vaccine Needs 80 Percent Efficiency With 75 Percent Uptake to Stop Pandemic in U.S.

For life to return to "normal," a coronavirus vaccine will need to have at least 80 percent efficiency, a computer model has found. By simulating different vaccine scenarios in a population, researchers from the U.S. looked at how effective a vaccine would need to be if it were to stop the pandemic alone.

The team, led by Bruce Y. Lee from the CUNY Graduate School of Public Health and Health Policy, found that if 75 percent of the population got the vaccine, 80 percent effectiveness would stop an ongoing epidemic. If only 60 percent got the vaccine, it would need to have 100 percent efficiency to extinguish the epidemic. Their findings are published in the American Journal of Preventive Medicine.

The computer model simulated the spread of COVID-19 and vaccination across the U.S. At present, there are no approved treatments for the disease, and current control methods are largely reliant on non-pharmaceutical interventions, such as social distancing, lockdowns and mask use. Because of this, there has been a huge focus on the development of a vaccine.

Countries across the world are working to develop vaccines, with 32 currently in the human trial stages, according to the New York Times vaccine tracker. Russia announced it had approved its vaccine, Sputnik V, earlier this month. The Russian Direct Investment Fund, which is helping to finance the vaccine, said 20 countries have expressed interest in it. On 20 August, the state-run Tass news agency said it would start vaccinating medics with Sputnik V the following week.

China also recently announced it had been giving its own vaccine to healthcare workers since July. According to CNN, Zheng Zhongwei, director of the Science and Technology Development Center of the National Health Commission, said China's laws clearly say that during a public health emergency, the country can authorize the emergency use of vaccines. He said that by vaccinating frontline workers, an "immunity barrier" could be established. They plan to roll out the vaccine to people who work in agriculture, transportation and service industries next, he added.

In the U.S. Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, warned against rushing out vaccines before their safety and efficiency had been proven. His comments followed reports that the Trump administration was hoping to push out a vaccine, potentially via emergency use authorization (EUA), before November's election. These claims were denied by White House officials.

Fauci had also previously spoken about the first vaccines to be developed, saying their efficiency would probably be low to start. Earlier this month, he said the chances of developing a vaccine that has a 98 percent effectiveness were "not great." He said scientists were hoping for efficiency of around 75 percent, but added 50 to 60 percent would also be acceptable. An effectiveness of around 50 percent would put a coronavirus vaccine in line with seasonal flu shots.

In June, Andy Slavitt, the former Acting Administrator of the Centers for Medicare and Medicaid Services under president Barack Obama, also said the first vaccines would probably have an efficiency similar to those for the flu, saying subsequent vaccines would get progressively more effective.

In the latest study, Lee and colleagues said it will be important to understand how effective a vaccine needs to be, and how many people will need to have it, if social distancing measures are to be removed altogether. Findings showed that with 100 percent update, a vaccine would still need to be at least 60 percent effective to stop the pandemic. If coverage falls to 75 percent, the vaccine would need to be 80 percent effective.

"Some are pushing for a vaccine to come out as quickly as possible so that life can 'return to normal,'" Lee said in a statement. "However, we have to set appropriate expectations. Just because a vaccine comes out doesn't mean you can go back to life as it was before the pandemic. It is important to remember that a vaccine is like many other products—what matters is not just that a product is available, but also how effective it is."

Stock image representing a coronavirus vaccine. Researchers have found a vaccine will need to be 80 percent effective if it is to stop the pandemic. iStock