Covid-19: Science can’t keep up with the virus, which worries vaccinated people

Anecdotes tell us what the data can’t: Vaccinated people seem to be surprisingly often infected with the coronavirus. But exactly how often is not clear, nor is it certain how likely it is that they will transmit the virus to others. And now there is growing concern that vaccinated people are more susceptible to serious illnesses than previously thought.
There is a lack of scientific studies with concrete answers, so business decision-makers and executives have to formulate plans based on fragmented information. While some renew mask requirements or delay office reopenings, others cite the lack of clarity to justify staying on course. It can all feel like a mess.
“We have to be humble about what we know and what we don’t know,” said Tom Frieden, former director of the Centers for Disease Control and Prevention and director of the nonprofit Resolve to Save Lives. “There are a few things that we can definitely say. One of them is that this question is difficult to answer. ”

Without clear public health messages, vaccinated people are confused about how to protect themselves. How vulnerable they are is a key variable not only for public health officials looking to figure out when to need booster shots, for example, but also to make decisions about whether to withdraw reopenings amid a new wave of the virus. On a smaller scale, the Unknowns have made music lovers unsure whether it is okay to see a concert, and has led to a new round of hill wrestling among parents as they ponder what the school will be like.
Instead of answers, a variety of case studies have emerged that provide slightly different pictures of breakthrough infections. Variables such as the time of the surveys, whether the Delta variant was present, how much of the population was vaccinated and even the weather at that time made it difficult to compare and identify patterns. It’s hard to say which dates could ultimately carry more weight.
“It’s very clear that we have more breakthroughs now,” said Monica Gandhi, an infectious disease expert at the University of California at San Francisco. “We all know someone who had one. But we don’t have great clinical data. ”
One of the most famous outbreaks among vaccinated people happened in the small beach town of Provincetown, Massachusetts when thousands of vaccinated and unvaccinated people gathered on dance floors and at house parties over the weekend of July 4th to celebrate the holiday – and what seemed like a turning point in the pandemic. About three quarters of the 469 infections affected people who were vaccinated.
Authors of a CDC case study said this could mean they are just as likely to transmit Covid-19 as unvaccinated ones. Even so, they warned that as more people are being vaccinated, it is natural that they will also make up a greater proportion of Covid-19 infections and this one study is not enough to draw conclusions. The incident prompted the CDC to reverse a recommendation it had made just weeks earlier and to re-urge those vaccinated to mask themselves in certain situations.
Still, the particular details of this group of cases may have made this outbreak particularly dire, according to Gandhi.
“The rate of mildly symptomatic outbreaks in this population was higher due to a lot of indoor activities (including intimacy), rain this weekend, little free time, and a mix of people with different vaccination statuses,” she said in an email.
Meanwhile, a newly published, much larger CDC case study of infections in New York State found that the number of breakthrough infections had risen steadily since May, accounting for nearly 4% of cases by mid-July. These researchers cautioned that factors such as the easing of public health restrictions and the rise in the highly contagious Delta variant could affect results.
Another CDC case study in Colorado found that one county, Mesa, had a breakthrough infection rate of 7% versus about 5%, significantly higher than the rest of the state. The report suggested that this may be because the Delta variant was more prevalent there, but also noted that the age of the patients in Mesa and the lower vaccination rate may have played a role.
Research from Israel has strongly suggested that immunity to the virus wears off in the months following vaccination and, more recently, that breakthrough cases can eventually lead to spikes in hospital admissions.
Case studies and data from some US states have also shown an increase in breakthrough cases over time. But since the Delta variant is also on the rise, it is difficult to say whether the dwindling immunity to any type of coronavirus infection is to blame or whether the vaccinations against the Delta variant are particularly ineffective. It can of course be both. Behavioral changes in vaccinated individuals could also be a factor when they return to social gatherings and travel and dine indoors.
Even so, some facts are well documented at this point. Vaccinated people infected with the virus are much less likely to go to hospital, need to be intubated much less, and are much less likely to die from the disease. There is no doubt that vaccines offer significant protection. But much of the nation – nearly 30% of US adults – was not vaccinated, a fact that has conspired with the highly contagious Delta variant to plunge the country into a new wave of outbreaks.
“The big picture here is that the vaccines are working, and the reason for the surge in the US is that we are getting too few vaccines,” said Frieden.
To some extent, breakthrough cases of viruses are expected. No Covid vaccine has been 100% effective in clinical trials – even the best vaccines never are. The more the virus is circulating, the greater the risk of breakthroughs. It is also common for some aspects of viral immunity to naturally diminish over time.
Right now there are simply more questions than answers. Are breakthrough infections ticking because of the Delta variant, declining immunity or a return to normal life? Are vaccinated people more susceptible to serious illnesses than previously thought? How common are breakthrough infections? It’s everyone’s guess.
“In general, we have to make public health decisions based on imperfect data,” said Frieden. “But we don’t know a lot.”