Though immunization reduces the risk of infection, severe illness, and death, no vaccine is 100% effective in that regard. Even after being fully vaccinated, a person may still contract and become ill from a virus. In some cases — particularly in individuals with underlying health conditions — severe infection, hospitalization, and death may occur. At the time of this writing, experts recommend that receiving one of three COVID-19 vaccines authorized by the FDA is still the best way to prevent the spread of COVID-19 and reduce one's chances of becoming severely ill.
As the U.S. saw a resurgence of COVID-19 cases in late summer 2021, speculation regarding the effectiveness of the three authorized vaccines circulated on the internet. Some of these concerns were prompted when local NBC affiliate News 4 San Antonio reported on Aug. 11, 2021, that a 48-year-old “fully vaccinated” Texas woman died after testing positive for COVID-19.
Tracy Anderson was fully vaccinated in February 2021, reported journalist Joe Galli. But she was also reportedly diagnosed with underlying health conditions including COPD, pulmonary hypertension, and diabetes — all of which have been deemed by health experts as co-morbidities of SARS-CoV-2 infection.
After intubation and a 12-day “battle with the virus,” the family’s GoFundMe page said that Anderson died on July 29 at 2:19 p.m.
After news of Anderson’s death was shared online, Snopes readers asked our team to investigate whether it is possible to die from COVID-19 even if an individual is vaccinated. In short, we found that no vaccine is 100% effective at preventing infection. And even after being fully vaccinated, it is still possible for a person to contract a virus and become ill from it. In some cases — particularly in individuals with underlying health conditions like Anderson — severe infection, hospitalization, and death may occur.
The Science of Vaccine Efficacy and Effectiveness
Like all vaccines, the three COVID-19 vaccines currently available in the U.S. offer differing rates of efficacy and effectiveness (more on that later, particularly as an uptick in delta cases has been at the source of “breakthrough infections” in already-vaccinated people. Though the delta variant is more contagious than previous variants, these “work well” against it, especially when it comes to reducing the likelihood of hospitalization and death.
But the efficacy rate of a vaccine does not mean that it only works that percentage of the time. As the World Health Organization pointed out, if a vaccine has an efficacy of 80%, it does not mean that the vaccine will only work 80% of the time. It means that in a vaccinated population, 80% fewer people will contract the disease when they encounter the virus. Efficacy is how scientists determine success rates in clinical trials. In the real world, on the other hand, vaccine effectiveness is used to measure how well a vaccine works to protect communities as a whole under differing, unpredictable conditions. That is where the concept of "herd immunity" comes into play: Because vaccines do not unequivocally guarantee full protection for everyone, as more people get vaccinated it becomes less likely for those without full immunity to come into contact with the virus.
Data from New York cases showed that the effectiveness of the Pfizer vaccine wanes over time, dropping from 91% to 79.8% effective in preventing infection, according to Yale Medicine. But ongoing research suggests that both Pfizer and Moderna vaccines can prevent severe disease in several variants more than 90% of the time. On the other hand, Johnson & Johnson showed 72% overall efficacy and 86% against severe disease in the U.S., according to an analysis published by the U.S. Food and Drug Administration (FDA) in February 2021.
“COVID-19 vaccines are effective at preventing infection, serious illness, and death. Most people who get COVID-19 are unvaccinated. However, since vaccines are not 100% effective at preventing infection, some people who are fully vaccinated will still get COVID-19. An infection of a fully vaccinated person is referred to as a “breakthrough infection,’” wrote the Centers for Disease Control and Prevention (CDC}.
Why Are We Seeing Breakthrough Infections if Vaccines Are Effective?
Courtney Bennett, a 29-year-old nursing student from Montana, was one such breakthrough case. Bennett received the first dose of her Pfizer vaccine on March 24 and a second dose on April 14. On Aug. 22, she attended a dinner party with ten other vaccinated individuals. The following day, Bennett told Snopes that she tested positive for COVID-19 the following day after learning that another dinner attendee had tested positive for the virus. At the time of our interview, Bennett, who does not have any known underlying medical conditions, said that her symptoms include fatigue, aches, and congestion — all of which she believes are lessened because she is vaccinated.
“I am seeing how effective the vaccine has been in this way since those that I was around that do have the virus and that are vaccinated are also only mildly symptomatic, if symptomatic at all,” said Bennett.
Still, she says that her breakthrough infection does not reduce her trust in vaccine efficacy.
"There is a huge misconception of the ability of the vaccine to prevent someone from getting COVID-19. Peer-reviewed information about the vaccine clearly states that the hope, with the vaccine, was to create herd immunity,” said Bennett.
But those with underlying conditions or compromised immune systems may still experience serious/severe symptoms.
“Vaccines are designed to generate an immune response that will protect the vaccinated individual during future exposures to the disease,” wrote The History of Vaccines, an educational website created by the medical society The College of Physicians at Philadelphia.
“Individual immune systems, however, are different enough that in some cases, a person’s immune system will not generate an adequate response. As a result, he or she will not be effectively protected after immunization.”
The CDC collects data on laboratory-confirmed COVID-19 associated hospitalizations across more than a dozen states. A look through the data available from March 1, 2020, to June 30, 2021, showed that the majority of COVID-19 adult hospitalization cases had an underlying condition — only 8% had no known condition.
In summary, no vaccine is 100% effective at preventing infection. Even after being fully vaccinated, a person may still contract and become ill from a virus. And in some cases (particularly in individuals who have underlying health conditions), severe infection, hospitalization, and death may occur. At the time of this writing, experts recommend that receiving one of three COVID-19 vaccines authorized by the FDA is still the best way to prevent the spread of COVID-19.
CDC. “Cases, Data, and Surveillance.” Centers for Disease Control and Prevention, 11 Feb. 2020, https://www.cdc.gov/coronavirus/2019-ncov/covid-data/covid-net/purpose-methods.html.
“COVID-19 Vaccination.” Centers for Disease Control and Prevention, 11 Feb. 2020, https://www.cdc.gov/coronavirus/2019-ncov/vaccines/effectiveness/why-measure-effectiveness/breakthrough-cases.html.
COVID-19 Hospitalizations. https://gis.cdc.gov/grasp/COVIDNet/COVID19_3.html. Accessed 26 Aug. 2021.
“Efficacy and Effectiveness.” Immunisation Advisory Centre, 26 July 2016, https://www.immune.org.nz/vaccines/efficiency-effectiveness.
Ellyatt, Holly. “Fully Vaccinated People Are Still Getting Infected with Covid. Experts Explain Why.” CNBC, 10 Aug. 2021, https://www.cnbc.com/2021/08/10/breakthrough-covid-cases-why-fully-vaccinated-people-can-get-covid.html.
“Fully Vaccinated People Are Still Getting Infected with Covid. Experts Explain Why.” CNBC, 10 Aug. 2021, https://www.cnbc.com/2021/08/10/breakthrough-covid-cases-why-fully-vaccinated-people-can-get-covid.html.
Staff, JOE GALLI |. WOAI. “Family Mourns after Fully Vaccinated Woman Dies from COVID-19.” WOAI, 11 Aug. 2021, https://news4sanantonio.com/news/local/family-mourns-after-fully-vaccinated-woman-dies-from-covid-19.
Top 20 Questions about Vaccination | History of Vaccines. https://www.historyofvaccines.org/content/articles/top-20-questions-about-vaccination. Accessed 26 Aug. 2021.
Vaccine Efficacy, Effectiveness and Protection. https://www.who.int/news-room/feature-stories/detail/vaccine-efficacy-effectiveness-and-protection. Accessed 26 Aug. 2021.