People who have been vaccinated against COVID-19 seem to be getting infected with alarming frequency, including Georgia Bulldog football players and people on social media, and that is driving talk of booster shots before waning protection against the coronavirus grows into a crisis that fills hospitals.
The Centers for Disease Control and Prevention said it knows of 12,908 hospitalizations or deaths among the 173 million people who had been fully vaccinated as of Aug. 30, though it hasn’t been closely tracking mild or asymptomatic instances of “breakthrough infections.”
Local health departments are trying to fill that gap and say the odds are still vastly in favor of people who get the shots. Available estimates show about 1 in 5,000 to 1 in 10,000 vaccinated people are infected on a given day, said Dr. Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security.
“The point about breakthrough cases to emphasize is that they are almost universally mild and do not require medical attention,” he said. “They are to be expected because vaccines are not bug zappers and they were designed to prevent serious disease, which they are doing tremendously.”
Washington state recently reported 21,757 COVID-19 cases among the 4.2 million Washingtonians who were fully vaccinated — or about 0.5%.
Officials in King County, which includes Seattle, said unvaccinated people are seven times more likely than vaccinated people to become infected and 49 times more likely to be hospitalized if they are infected.
Yet those hoping to avoid any infection at all, particularly if it forces them out of work or to sit out social events, are being challenged by the aggressive delta variant.
Unvaccinated people were 10 times more likely than vaccinated people to become infected before the delta variant hit and only five times more likely after it arrived, according to a study that tracked people in Los Angeles County from May to July.
The CDC has repeatedly said the COVID-19 vaccines are good but not perfect protection against the coronavirus and warn that as the percentage of vaccinated Americans increases, the proportion of infections classified as “breakthrough” will naturally rise.
Still, well-publicized reports of cases in vaccinated people, particularly among pro and college athletes, who are tested frequently, are complicating President Biden’s push to get shots in arms.
“I think there’s a perception issue and an expectation that when we said the vaccines were 95% effective, a lot of average persons thought, ‘That’s it, I don’t have to think of this at all,’ ” said Dr. William Schaffner, an infectious disease specialist at Vanderbilt University. “Then along came delta, and delta changes that equation. It’s better able to produce these mild, breakthrough infections than did the old alpha strain.”
A New York state study showed a decrease in protection against infection from 92% in May — relatively early in the rollout — to 80% in July. A national study of 14,000 nursing homes found protection against infection dropped from 75% in March, the pre-delta era, to 53% by Aug. 1.
Those figures alarmed the Biden administration, which is pushing regulators to suggest booster shots, or third doses, of the Pfizer-BioNTech and Moderna vaccines for people who completed their initial course up to eight months ago.
“Our anticipation is that if the trajectory that we are seeing continues, then we will likely see, in the future, an increase in breakthrough hospitalizations and breakthrough deaths. And that’s why we used our judgment” in recommending boosters, U.S. Surgeon General Vivek Murthy recently told reporters.
Also, a midsummer study from Cape Cod, Massachusetts, found that some vaccinated people who experienced breakthrough infections could transmit the virus as efficiently as unvaccinated people in some instances.
The Provincetown study prompted federal officials to reverse guidance and recommend that people wear masks indoors in high-transmission areas, regardless of vaccination status.
The shifting data and the delta threat are affecting the American psyche, according to a recent Washington Post-ABC News poll, which found that nearly half of adults — 47% — had a high to moderate fear of contracting COVID-19.
That was up 18 percentage points from late June, even as the share of adults who were vaccinated gradually rose.
“Does anyone besides me feel that the messaging over the last month in the US has basically served to terrify the vaccinated and make unvaccinated, eligible adults doubt the effectiveness of the vaccines?” Dr. Monica Gandhi, a professor of medicine at the University of California, San Francisco, tweeted this month.
Some employers are mandating the shots, and federal officials are pleading with people to get vaccinated for themselves and for others. They highlight studies that find vaccinated people are still less likely to get infected and spread the virus than the unvaccinated.
A study from Los Angeles County found the incidence of infection among unvaccinated people was 315.1 per 100,000 in any given seven-day period from May 1 to July 25 compared with a 63.8 per 100,000 incidence rate among fully vaccinated people.
Data from Singapore suggests that vaccinated people may transmit the virus for a shorter period than unvaccinated people and that vaccinated people who transmit the virus tend to exhibit symptoms — an important concept that, if confirmed by additional study, could help businesses and schools operate by asking vaccinated people with coldlike symptoms to stay home.
“At the moment, the vast highway of transmission — and there are lots of cars on that highway — are the unvaccinated people,” Dr. Schaffner said. “They are the source of the vast majority of infections. It affects them, but that causes the spillover into vaccinated persons who get a milder infection but can also for a brief period of time turn into transmitters.”
A study from Britain found that vaccinated people were about 50% less likely than unvaccinated people to experience drawn-out symptoms, often known as “long COVID.”
Only 53% of the U.S. population is fully vaccinated against COVID-19, and parts of the country with the lowest rates are generally experiencing higher transmission.
“The more prevalent the infection is in a geographic area, the more likely one is to come into contact with the virus,” said Dr. Adalja. “Breakthrough infections, though rare, will occur at higher rates in high-transmission areas.”
Right now, the largest outbreaks are in the South. It’s not clear whether the highly vaccinated places in the Northeast will have large outbreaks or whether their higher vaccination rates will prove a sufficient bulwark in the colder months when respiratory diseases tend to thrive.
Scientists say vaccinated people need to use their judgment on masking, avoiding crowds and taking other precautions despite the odds that any case will be relatively mild.
“What level of protection they deem necessary is a matter of personal risk tolerance,” Dr. Adalja said.
Crowds at college football games could provide a live test of how vaccination requirements impact transmission in the coming weeks.
Some colleges, such as Louisiana State University, require proof of vaccination or a negative test, and San Jose State requires unvaccinated people to wear masks. Auburn University and the University of Florida haven’t required masks in their outdoor stadiums.
Kirby Smart, the head coach of the University of Georgia football team, said he has seen many infections among the team, making it hard to maintain a full roster and mount a successful season.
“We’re talking about breakthroughs,” he told the Athens Banner-Herald. “That concerns you, not only for players on the team that are unvaccinated that are playing and not playing because we want everybody to be safe, but it concerns for players that are vaccinated that we could lose them. This is the highest we’ve been since fall camp right now.”