Fact Check-SARS-CoV-2 virus began mutating prior to mass vaccine rollouts

SARS-CoV-2 variants are not caused by vaccines and numerous Variants of Concern (VOC) were detected prior to mass rollouts of vaccines, despite suggestions to the contrary online.

One tweet that has been screenshotted and shared widely on Facebook reads: “Very odd that covid barely “mutated” for a year but once vaccines rolled out, suddenly a whole Greek alphabet of “variants” appeared. But the unvaccinated are somehow at blame and are most at risk? Logic, folks. It’s a life saver” (here).

Examples can be found (here), (here), (here), (here), and (here).

One individual who shared a screenshot of the tweet on Facebook commented: “Wake. Up” accompanied by the hashtag, “the vaccines are the variants” (here).

Meanwhile, another user on Instagram screenshotted an article regarding Delta variant cases in school-age children and claimed that “mass vaccination during a pandemic puts pressure of the virus to mutate and become more infectious.”

They also claimed that vaccines encourage a virus to “mutate and infect younger age groups so it can travel easily” (here).

However, it is misleading to suggest that the virus has mutated in response to the rollout of vaccinations.

A Reuters article published on Dec. 10, 2020, about mutations creating at least seven different variants of the virus at the time of publication can be seen here .

On Jan. 28, 2021, the Centers for Disease Control and Prevention (CDC) released a briefing on variant surveillance (here).

In the briefing, the CDC detailed how several variants emerged in the fall of 2020.

The Alpha and Beta variants were designated as VOC by the World Health Organization (WHO) on Dec. 18, 2020. Meanwhile, the Gamma variant, which was first detected in Brazil, was listed as a VOC on Jan. 11, 2021.

The Delta variant, which was first detected in India, was designated a VOC in April 2021 (here). However, it was not caused by mass rollouts of vaccines, which began largely from the start of 2021.

“Early in the pandemic, only a limited number of labs were sequencing virus from infections, but since late 2020, surveillance programs have been ramping up,” Professor Jennifer Grier, Clinical Assistant Professor in Immunology at the University of South Carolina, told Reuters via email.

“Effectively, we are hearing so much more about viral variants in 2021 because, globally, we now have the systems in place to consistently detect and track mutations,” Grier added.

On May 31, the WHO assigned Variants of Interest (VOI) and VOC to letters of the Greek alphabet to simplify discussion and to curb stigma (here).

“I think the recent change to Greek letter names has made it easier to follow reports about specific variants, but the name changes might have made it seem as if a whole bunch of new variants appeared all at once,” Grier said.

A piece published in The Conversation in February 2021 details how viruses such as SARS-CoV-2 mutate (here) while a WHO video also details how viruses change, viewable here (here).

The vaccines have also not caused the virus itself to mutate.

“Virus mutations arise when the virus is replicating in a cell. None of the available vaccines contain live virus, so they cannot directly be the source of a viral variant,” Grier said.

“For the most part, the coronavirus vaccines reduce the risk of getting infected, and with fewer infections, there is less replicating virus so the chance of producing new variants decreases as well,” she added.

Reuters previously addressed the claim that variants have been caused by COVID-19 vaccines (here) and claims that the Delta variant only affects early age groups (here).


Missing context. Variants of SARS-CoV-2 were being monitored in 2020, prior to mass vaccine rollouts. Vaccines have not caused the emergence of variants.

This article was produced by the Reuters Fact Check team. Read more about our fact-checking work here .