UNITED STATES: A 2015 paper on a chicken virus showed vaccines could enable more deadly variants to spread – in chickens. But that outcome is rare. Only a minority of human and animal vaccines have affected the evolution of a virus.
In most of those cases, evolution didn’t increase the severity of the pathogen. The hypothetical possibility that the COVID-19 vaccines could result in more harmful variants is no reason to avoid inoculation. Rather, it shows the need to continue developing vaccines. In 2015, my collaborators and I published a scientific paper about a chicken virus you have likely never heard of.
At the time, it got some media attention and has been cited by other scientists in the years since. But now, by late-August 2021, the paper has been viewed more than 350,000 times – and 70% of those views were in the past three weeks. It has even appeared on a YouTube video that’s been seen by 2.8 million people, and counting. The paper has gone viral because some people are using it to stoke paranoia that the COVID-19 vaccines will cause the virus to evolve in the direction of even more severe variants. Doctors have told me that patients are using the paper to justify their decision to not get vaccinated.
Some pundits are even using it to urge an end to vaccination campaigns in order to prevent the sort of viral evolution we were studying in chickens. I am receiving emails daily from people worried about getting vaccinated themselves or worried about people rejecting vaccination because of misunderstandings about the paper. Nothing in our paper remotely justifies an anti-vaccine stance. That misinterpretation – if it causes people to choose not to be vaccinated – will lead to avoidable, and tragic, loss of life. A new study estimates that as of early May 2021, vaccines had already prevented nearly 140,000 deaths in the US.
For over 20 years I’ve been working with collaborators and colleagues on how vaccines might affect the evolution of disease-causing organisms like viruses and malaria parasites. Nothing we have discovered or even hypothesized justifies avoiding or withholding vaccines. If anything, our work adds to reasons for investigating new vaccine schedules – and for developing second- and third-generation vaccines.
But in the context of the COVID-19 virus, our work does prompt a fair question: Could vaccination cause the emergence of even more harmful variants?
