Over the past few months, a steady pace of headlines has highlighted the incredible real-world effectiveness of Covid-19 vaccines, especially mRNA vaccines made by Pfizer-BioNTech and Moderna. Vaccines, study after study, have been shown to be over 90 percent effective in preventing the worst consequences, including hospitalization and death.
But alongside this good news, there have been rare cases of severe Covid in fully vaccinated people.
On June 3, for example, Napa County announced that a fully vaccinated woman, who was more than a month after her second injection of Moderna, had died after being hospitalized with Covid. The woman, who was over 65 and had underlying health issues, had tested positive for the Alpha variant, which was first identified in Britain.
While these cases are tragic, they are rare – and not unexpected.
“I am very sad that she had an illness severe enough that it actually resulted in her death,” said Dr William Schaffner, medical director of the National Foundation for Infectious Diseases and vaccine expert at the Vanderbilt University. But, he noted, “we expected to have occasional breakthrough infection.”
Such cases should not deter people from getting vaccinated, the scientists said. “No vaccine in history has ever been 100% effective,” said Dr. Paul Offit, director of the Vaccine Education Center at Children’s Hospital of Philadelphia. “This is your best chance to avoid serious and critical illness. But like everything in medicine, it’s not perfect.
Severe Covid is rare in fully vaccinated people. In an article published last month, the Centers for Disease Control and Prevention said it had received reports of 10,262 breakthrough infections as of April 30. This is only a tiny fraction of the 101 million Americans who had been vaccinated by that date, although the agency noted that it likely represented “a substantial undercoverage” of breakthrough infections.
Of these groundbreaking cases, 10 percent of patients were hospitalized and 2 percent died – and in some of these cases, patients were hospitalized or died from something unrelated to Covid-19. The median age of those who died was 82 years old.
Older people, who are at greater risk of complications from Covid, may also be more likely to develop breakthrough infections because they are known to develop weaker immune responses to vaccines. People who are immunocompromised or have other chronic health conditions may also be at increased risk.
Some of the variants – particularly Beta, which was first identified in South Africa – may be more likely to escape vaccine-induced protection. But beta is currently not common in the United States, noted Dr. Schaffner.
The Alpha variant that infected the Napa County woman is highly contagious, but the vaccines offer good protection against her – as well as against the original strain of the virus.
“Stories of groundbreaking infections, while extraordinarily rare, can be confusing to the public,” said Dr Karen Relucio, Napa County public health official, in an emailed statement. “We know that when stories like this emerge it might be tempting for some to question the effectiveness of vaccines.”
But vaccines are very effective, she said. In Napa County, the rate of major infections is only 0.04% among fully vaccinated people, she said.
Statewide, the rate is even lower. According to the California Department of Health, as of June 2, there had been 5,723 revolutionary cases among more than 17.5 million fully vaccinated residents, for a rate of 0.032%. Of these cases, only 7 percent were hospitalized and 0.8 percent died. Even in these cases, it is not known if Covid was the leading cause of death.
Peak infections are likely to decrease as more people get vaccinated and transmission rates in the community decline. “The virus will find fewer and fewer people to infect – it will be more difficult for the virus to make its way through the population,” said Dr Schaffner. “These are great vaccines. For vaccines to work optimally – on an individual and community basis – as many people as possible need to be vaccinated. “