As the virus that causes COVID-19 has evolved, the vaccines have become less effective in preventing symptomatic infection while remaining highly effective in preventing severe disease and death. This shift has been misrepresented by anti-vaccine influencers who falsely claim that it means the vaccines don’t work and have been ineffective all along.
Viruses mutate, or change, as they replicate. That’s largely why the currently available vaccine formulas aren’t working as well at preventing infection with the virus that causes COVID-19.
Those vaccines — made by Moderna, Pfizer/BioNTech and Johnson & Johnson — were highly effective in preventing both symptomatic infection and serious illness against early strains of the virus. But they are less effective against infection from the currently circulating subvariants of the omicron variant.
Public health officials have acknowledged this shift and changed their advice accordingly, in an effort to deal with a disease that became the third-leading cause of death in the U.S. in 2020 and 2021 and has killed more than a million people across the country.
But anti-vaccine campaigners and those who have cast doubt on the severity of COVID-19 have twisted those remarks to suggest that the health care establishment had given faulty advice about the value of the vaccines from the beginning.
For example, conservative influencer David Harris Jr. — who has 1.5 million followers on Instagram — posted a pair of video clips featuring Brett Sutton, the chief health officer for the Australian state of Victoria. One clip is from April, showing Sutton encouraging people to get a booster shot, saying that it can help keep people from “getting infected in the first place.” The other clip shows part of a press conference from August, as Victoria was experiencing a surge in cases, where Sutton said: “Despite two, three, four doses of the vaccine, it’s not so good at preventing infection in the first place.”
Harris didn’t include the dates of the clips — he labeled them only “Then” and “Now.” In the caption, he referred to his earlier claim that the COVID-19 vaccine “doesn’t work,” writing: “I wonder which of my other conspiracy theories will be proven true next???”
Similar claims have been ubiquitous on social media and beyond. They’ve been posted on platforms such as the right-wing website Gateway Pundit, which claimed in a headline that the Centers for Disease Control and Prevention “finally admits their vaccines do not prevent anyone from getting or spreading the virus.”
And they’ve shown up on a San Diego television station that has a history of promoting dubious claims about COVID-19. The station featured a guest who claimed the CDC had said of the vaccines, “turns out they don’t really work anyway,” and that CDC officials “knew they weren’t really going to do what we said they would.”
That guest was Dr. Kelly Victory, who holds an active medical license in both Colorado and Ohio, but according to her LinkedIn profile has spent the last 16 years as a consultant for disaster preparedness training. She also campaigned against the Affordable Care Act in 2012.
Victory has advocated against most public health advice over the course of the pandemic, claiming that “masks don’t work” and that asymptomatic spread “simply doesn’t occur with respiratory viruses.” In one talk radio appearance in 2021, Victory said that she had been “censored” for making those claims. But her claims just aren’t true.
Other related claims have been pervasive online, such as the meme shared by Donald Trump Jr. suggesting that recently updated guidance from the CDC matches what those who have downplayed the severity of the pandemic and questioned the value of the vaccines had been saying all along.
But the new guidance doesn’t indicate that health care experts were wrong about the vaccines or any other mitigation measures they had recommended.
Highly Effective Against Initial Outbreak
“The truth is, the effectiveness of vaccines shifted with each of the new variants,” Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, told us in a phone interview.
When the vaccines were approved for emergency use in 2020, they were approved based on their demonstrated ability to prevent symptomatic illness, he said. And large clinical trials showed that the efficacy was high.
For example, the updated trial results reported to the Food and Drug Administration for full approval showed the Moderna vaccine was 93.2% effective in preventing symptomatic disease at least two weeks after the second dose in people 18 years of age and older.
The vaccines were also highly effective when they were first introduced to the public in the real world.
“The initial SARS-CoV-2 that we had, that initial wild type, the vaccine against it did work against infection,” Dr. Rochelle Walensky, director of the CDC, said in a recent interview on Fox News. “It worked actually quite well against infection. It also worked against severe disease and death.”
A promising early study from Israel showed that the vaccines had been more than 90% effective in preventing both symptomatic illness and asymptomatic infection in the early days after the rollout.
“That was really exciting because it meant that, maybe, we could vaccinate our way out of this pandemic,” Hotez said.
After the first variant, alpha, emerged, the vaccines remained highly effective against infection, severe disease and death, Walensky said.
In May 2021, the CDC said that those who were fully vaccinated could stop wearing masks.
Then the virus mutated, and the delta variant became dominant in the summer of 2021.
Recommendations Evolved With Variants
Although the vaccines remained effective against severe illness and death from COVID-19, they were somewhat less effective at preventing infection from delta.
That’s when the CDC reversed its recommendation and said that those who were vaccinated should wear a mask indoors.
That fall, the Biden administration made booster shots available.
The virus keeps changing, and subvariants of omicron are now dominant. It’s become increasingly clear that the vaccines are less effective in preventing infection than they had been with earlier variants.
This is due to two things, Hotez said — changes to the virus and the natural decline in the potency of vaccination over time, which happens with most vaccines.
The CDC noted the waning effect of immunity from the vaccines in an August report explaining the most recent changes to its guidance on COVID-19 prevention, which included a recommendation for booster doses.
“Overall booster dose coverage in the United States remains low, which is concerning given the meaningful reductions in risk for severe illness and death that booster doses provide and the importance of booster doses to counter waning of vaccine-induced immunity,” according to the paper, which was published in the CDC’s Morbidity and Mortality Weekly Report on Aug. 11.
It also noted that the vaccines are “highly protective” against severe disease and death, and that they offer “minimal protection against infection and transmission.” That last part is what Victory and others highlighted, while neglecting to mention how effective the vaccines are against serious illness.
Victory claimed that the CDC had “acknowledged” that the vaccines were “essentially ineffective.”
But that’s not accurate.
As we said, the CDC explained that being up to date with vaccination offers minimal protection from infection, but, importantly, significant protection against severe disease. Being up to date with vaccination means that you’ve gotten the primary series of doses and any boosters that are available for your age group, the CDC has explained.
“Being up to date with vaccination provides a transient period of increased protection against infection and transmission after the most recent dose, although protection can wane over time,” the CDC said. The rates of hospitalization and death are “substantially higher” among unvaccinated adults, especially those 65 and older, compared with those who are up to date with vaccination, the CDC also said.
In fact, data from the COVID-19 Associated Hospitalization Surveillance Network for March 20 through May 31, 2022, showed: “Hospitalization rates among unvaccinated adults were 3.4 times as high as those among vaccinated adults,” according to an Aug. 26 CDC report.
Editor’s note: SciCheck’s COVID-19/Vaccination Project is made possible by a grant from the Robert Wood Johnson Foundation. The foundation has no control over FactCheck.org’s editorial decisions, and the views expressed in our articles do not necessarily reflect the views of the foundation. The goal of the project is to increase exposure to accurate information about COVID-19 and vaccines, while decreasing the impact of misinformation.
Cox, Elizabeth. “What is a coronavirus?” Yale School of Medicine. Updated 3 Sep 2020.
National Institutes of Health. Press release. “COVID-19 was third leading cause of death in the United States in both 2020 and 2021.” 5 Jul 2022.
Centers for Disease Control and Prevention. COVID Data Tracker. Accessed 26 Aug 2022.
McDonald, Jessica. “The Evolving Science of Face Masks and COVID-19.” FactCheck.org. Updated 20 Jan 2022.
McDonald, Jessica. “Unpacking WHO’s Asymptomatic COVID-19 Transmission Comments.” FactCheck.org. 12 Jun 2020.
Centers for Disease Control and Prevention. Press release. “CDC streamlines COVID-19 guidance to help the public better protect themselves and understand their risk.” 11 Aug 2022.
Hotez, Peter. Dean, National School of Tropical Medicine at Baylor College of Medicine. Telephone interview with FactCheck.org. 23 Aug 2022.
Walensky, Rochelle. Interview with Neil Cavuto. Your World. Fox News. 23 Aug 2022.
Dagan, Noa, et al. “BNT162b2 mRNA Covid-19 Vaccine in a Nationwide Mass Vaccination Setting.” New England Journal of Medicine. 15 Apr 2021.
Centers for Disease Control and Prevention. Interim Public Health Recommendations for Fully Vaccinated People. Updated 13 May 2021.
McDonald, Jessica. “Vaccines Remain Largely Effective Against Delta Variant, Counter to Claims From Fox News Guest.” FactCheck.org. Updated 10 Feb 2022.
Kiely, Eugene. “Misinformation About Face Masks.” FactCheck.org. 13 Aug 2021.
Cohen, Jon. “How long do vaccines last? The surprising answers may help protect people longer.” Science. 18 Apr 2019.
Massetti, Greta, et al. “Summary of Guidance for Minimizing the Impact of COVID-19 on Individual Persons, Communities, and Health Care Systems — United States, August 2022.” Centers for Disease Control and Prevention. Morbidity and Mortality Weekly Report. 11 Aug 2022.
Centers for Disease Control and Prevention. “Stay Up to Date with COVID-19 Vaccines Including Boosters.” Updated 23 Aug 2022.
Havers, Fiona, et al. “Laboratory-Confirmed COVID-19–Associated Hospitalizations Among Adults During SARS-CoV-2 Omicron BA.2 Variant Predominance — COVID-19–Associated Hospitalization Surveillance Network, 14 States, June 20, 2021–May 31, 2022.” Centers for Disease Control and Prevention. Morbidity and Mortality Weekly Report. 26 Aug 2022.