How Effective Does a Vaccine Need to Be to Stop the Pandemic?


People across the country — and around the world — are anxious for a vaccine to put an end to the novel coronavirus pandemic. But a new study shows that any COVID-19 vaccine would have to offer a high level of protection for people to resume life as normal.

In the study published in the American Journal of Preventative Medicine, a group of researchers from the CUNY Graduate School of Public Health and Health Policy worked to determine how effective such a vaccine would need to be and how many people would have to take it to end the public health crisis. 

“This study found that the vaccine has to have an efficacy of at least 70% to prevent an epidemic and of at least 80% to largely extinguish an epidemic without any other measures (e.g., social distancing),” the authors concluded.

Developers have been working to develop a vaccine to treat the illness since COVID-19 broke out, with more than 4 million people infected and 150,000 dead in the U.S. News of potential vaccines have made headlines, but the researchers say a vaccine that has a low level of effectiveness may mean people have to continue social distancing even after the vaccine is here.

The researchers used a computer simulation of every person in the country to determine the necessary efficacy of a potential vaccine. 

“Based on these findings, a vaccine with an efficacy as low as 60% could still stop the pandemic and allow society to return to normal. However, most if not all of the population would have to be vaccinated,” CUNY SPH’s Bruce Y. Lee wrote in The Conversation

Lee adds: “However, it is important to remember that a vaccine is like many other products: What matters is not just that the product is available but also how effective it is. Take clothing for example. If you are going to a formal dinner, underwear alone may partially cover you but probably not well enough for the occasion. This doesn’t mean underwear is useless.”

The CUNY SPH researchers on the study include Sarah M. Bartsch, Kelly J. O’Shea, Marie C. Ferguson, Patrick T. Wedlock, Sheryl S. Siegmund, Sarah N. Cox, and Lee.