You asked, we answered: Are leaky vaccines causing the new COVID-19 mutations?

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I've heard that the COVID-19 vaccines are “leaky,” and that's why we're getting all these new COVID-19 mutations. Are leaky vaccines causing these dangerous COVID-19 mutations?

Answer from infectious diseases expert James Lawler, MD:

The vaccines are not directly responsible for the mutations occurring in SAS-CoV-2, the virus that causes COVID-19. 

Viruses mutate at a predictable frequency. We use that predictable mutation rate to determine where a virus came from, and how long ago it emerged. 

The ability of the SARs-CoV-2 virus to mutate and create new variants is mostly dependent on the amount of virus replicating. In other words, when there are more people infected with the virus that causes COVID-19, there is more possibility for mutations to occur and new variants to arise. 

The timeline for this claim also doesn't add up. The most problematic variant we've dealt with so far, the delta variant, was first isolated in October 2020 in India, from a sample collected in September 2020. India didn't begin a public vaccination campaign until Jan. 16, 2021. 

Below I've outlined all the variants of concern currently in the U.S., along with their country of origin, earliest sample date and when public vaccination began in each country. 


  • Location first detected: United Kingdom
  • Earliest sample date: Sept. 3, 2020
  • The U.K.'s vaccination efforts began Dec. 8, 2020


  • Location first detected: South Africa
  • Earliest sample date: Sept. 1, 2020
  • South Africa's vaccination efforts began Feb. 17, 2021


  • Location first detected: Brazil
  • Earliest sample date: Oct. 1, 2020
  • Brazil's vaccination efforts began Jan. 18, 2021


  • Location first detected: India
  • Earliest sample date: Sept. 22, 2020
  • India's vaccination efforts began Jan. 16, 2021

As you can see, all of the mutations we're currently dealing with emerged well before the COVID-19 vaccines were publicly available. Learn more about the variants of concern in the U.S. 

Vaccinating a large portion of the population will reduce the overall number of infections. Reducing the number of infections reduces the opportunities the virus has to mutate into new variants

Getting vaccinated, and encouraging your loved ones to get vaccinated, is the best way to prevent more dangerous future mutations.