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VERIFY: Can vaccines be approved without being 100% effective?

The VERIFY Team looked into the criteria needed for the FDA to approve a vaccine. The agency will approve a vaccine with an 'Efficacy Rate' of 50 percent and up.

WASHINGTON — Question:

How effective does a vaccine need to be, for it to be approved in the United States?

Answer:

Public health experts told the VERIFY Team that vaccines are never truly 100 percent effective. Nonetheless, they offer significant health benefits to the population, even at just 50% effectiveness. 

According to the FDA’s June guidance, a vaccine will be approved if it is safe, and at least 50 percent effective over the placebo. 

Sources:

Food and Drug Administration

The Centers For Disease Control and Prevention

The World Health Organization

Dr. Linda Nabha, Infectious Disease Specialist

Process:

Earlier this week the bio-pharmaceutical company, Pfizer, announced that early data showed that the effectiveness of their COVID-19 vaccine may be as high as 90%.

The VERIFY Team looked into the criteria for a vaccine to be approved, since some on social media claim that this can be done for a vaccine that is as low as 50-percent effective. 

The VERIFY Team got the most definitive answer from the Food and Drug Administration, which approves vaccines in the United States. According to their June guidance, 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."

"This is the low end of what FDA would consider for authorization or approval," said an FDA spokesperson. "With the hope that effectiveness would be higher."

Dr. Linda Nabha, an infectious disease specialist, emphasized that we're actually talking about the 'efficacy rate,' and not the effectiveness. She said the 'Efficacy Rate' is a measurement of how effective a vaccine is in a controlled environment, like a study. 

"In these trials, we use terms like 'vaccine efficacy,'" she said. "But when it gets out in the real world, this vaccine - we're going to talk about vaccine effectiveness."

It's not unusual for a vaccine to be approved, without being 100% effective, according to the World Health Organization.

"No vaccine is 100 percent effective," wrote the WHO on their website. "To make vaccines safer than the disease, the bacteria or virus is killed or weakened (attenuated). For reasons related to the individual, not all vaccinated persons develop immunity.”

The Centers For Disease Control and Prevention reiterated this point on their website.

"Vaccines are the best defense we have against infectious diseases," the CDC wrote on their website. "But no vaccine is actually 100% safe or effective for everyone because each person’s body reacts to vaccines differently.”

According to the CDC, recent studies have shown that the flu vaccination reduces the risk of flu illnesses by just 40 to 60 percent. Even the MMR Vaccine, which protects against measles, is not perfect, with an effectiveness of 97 percent, according to the CDC

Dr. Nabha said that a vaccine can be incredibly important for a community, even if it's not 100 percent effective. She said the flu vaccine is a prime example.

"People who get the vaccine may sill get the flu," she said. "With the flu vaccine. But the most part their disease is milder than if they hadn't had the vaccine."