“Over time there’s some selection going on,” said Dr. A study at the University of California, San Francisco found breakthrough infections among vaccinated people were more commonly associated with slightly more antibody-resistant strains of the coronavirus than those seen in unvaccinated people. There are also some indications the virus must work harder to infect vaccinated people.

The unvaccinated are 14 times more likely to die from COVID-19 than people who are vaccinated.īeing vaccinated is also more protective than having recovered from an earlier case of COVID-19 and having what is known as natural immunity.Ī large study by the Centers for Disease Control and Prevention published in October found that unvaccinated people who had had a recent infection were five times more likely to get COVID-19 than those who were fully vaccinated and had not had a prior infection. The biggest contrast, of course, is that people who are unvaccinated are 5.8 times more likely to get COVID-19 than vaccinated people. More information about how breakthrough cases work is becoming available as the pandemic progresses and researchers investigate the differences between vaccinated and unvaccinated COVID-19 patients. Genomic analysis of breakthrough infections

'In a person who's been vaccinated, in the viral genetic material they produce, the virus is chopped up and weakened, because their immune system is fighting the virus, so it's less likely to be infectious,' he said. Kissler cautioned that even if vaccinated and unvaccinated people produce the same amount of viral material, that doesn't necessarily represent how capable they are of causing infection. 'It seems to be not so much that people with delta are producing huge amounts of virus but that the virus is better able to infect our cells,' he said.

There had been some early research suggesting the delta coronavirus variant produced as much as 1,000 times as much virus as other variants. The study, published Wednesday in the New England Journal of Medicine, also found that different coronavirus strains produce about the same amount of the virus, which hadn’t been clear before. Usually, we only see the virus once a person has symptoms, when they're at peak.' 'This allowed us to uncover what infections look like in the very early stages.

Chan School of Public Health and co-author on the paper. 'Most of them were getting tested every day or every other day,' said Stephen Kissler, an infectious disease fellow at the Harvard T.H. The researchers took 19,941 viral samples from 173 National Basketball Association players, staff and their families between November 2020 and August. They compared the viral dynamics of those infected with various coronavirus variants and the course of illness in players who were vaccinated and unvaccinated. The study, which involved NBA players, their families and staff, found that people with breakthrough COVID-19 cases stopped producing the virus two days sooner than the unvaccinated. The vaccinated people who got COVID-19 cleared the virus from their systems on average in 5½ days. New research about breakthrough coronavirus infections finds they may be less likely to spread to others because vaccinated people don't shed the virus for as long as the unvaccinated. Watch Video: Moderna: Vaccine protection waned amid delta surge

Vaccinated people transmit virus