5 New Things We Learned About COVID-19 In July 2021

Here's the latest, from how likely it is to spread the virus when you're vaccinated to an alarming discovery about its effect on the brain.
Researchers are learning more about COVID-19 every month.
zhengshun tang via Getty Images
Researchers are learning more about COVID-19 every month.

What we know about COVID-19 seems to change by the minute.

It’s understandable, given the massive scale of the pandemic. Right now, more than 196 million cases have been confirmed around the world. And even a year-plus into the pandemic, the virus and ways to address it are still relatively new to the medical world, so researchers are learning as they go.

The amount of information out there about the coronavirus is dizzying. It’s hard to keep track of what’s known, what’s a myth and what guidance we should follow. That’s why we’ve rounded up five of the most important new things we learned about COVID-19 in July:

1. People with breakthrough infections are 80% less likely to spread the virus — but with delta, that figure is more complicated.

Doctors and health officials have believed for months now that people who are fully vaccinated against COVID-19 are much less likely to spread the virus. And two studies out of Israel published in July support that idea, showing that even when fully vaccinated people have a breakthrough infection, they’re about 80% less likely to spread the virus to other people in their homes. The study was conducted in people who received the Pfizer shots.

These results offer a more concrete estimate of just how much vaccination reduces transmission — something that had largely been inferred from other research, experts say. Of course, the vaccines’ primary benefit is to keep people from getting really sick or dying, but “the fact that they also reduce the infectiousness of breakthrough cases is important and reassuring,” an author one the Israel studies told Nature.

However, the big question mark in all of this is the delta variant, which is more contagious than the other virus strains — and was not looked at in the two Israel studies. There is now emerging evidence now that people with breakthrough cases of COVID-19 who are infected with the delta variant may be just as infectious as those who are unvaccinated, The New York Times and The Washington Post reported. This accounts for why the Centers For Disease Control and Prevention recently tightened its recommendations on mask wearing in high transmission areas.

2. Long-haul COVID has more than 200 symptoms.

Although there are some symptoms of long-haul COVID that tend to be relatively common, like brain fog and shortness of breath, a study published in July showed just how wide-ranging the condition can be. The findings, which relied on reports from members of a global long-haul COVID support group, linked the condition to 203 symptoms that impact 10 different organ systems — including everything from heart palpitations to reported menstrual cycle changes and memory loss.

While there are significant limitations to the study — primarily, that it relied on patient reports, and that there is no way to verify whether the reported symptoms were a direct result of COVID-19 — the team behind the research said it highlights a pressing need for more research around the condition.

“In this unique approach, we have gone directly to ‘long haulers’ around the world in order to establish a foundation of evidence for medical investigation, improvement of care, and advocacy for the long COVID population,” the researchers noted.

3. COVID may accelerate Alzheimer’s-like symptoms.

Doctors have long known that COVID-19 can have significant neurological effects, and startling new research presented at the Alzheimer’s Association International Conference in July adds to that knowledge, suggesting the virus may be associated with an acceleration of Alzheimer’s-like symptoms.

The small study, which focused on 200 adults over the age of 60 who had COVID, found that more than half still struggled with forgetfulness three to six months after their initial infection, CNN reported. About a quarter of people experienced more significant cognitive challenges that are slightly different than those seen in younger patients with so-called “brain fog.” The researchers also found that how sick a patient was with COVID-19 didn’t ultimately indicate whether they experienced those subsequent cognitive issues.

It’s not yet clear whether those types of symptoms might improve with time or worsen, as is the case with Alzheimer’s.

Another study presented at the conference found that patients over the age of 60 who tested positive for COVID-19 also had blood biomarkers that tend to be found in Alzheimer’s patients — though it’s too early to know what that means in terms of peoples’ outcomes.

“Those are the kinds of things that make you suspicious that indeed there may be an overlap with Alzheimer’s disease, of some sort,” one researcher told CNN. “But it’s very early in the game. We need a lot more data.”

4. Remdesivir may be linked to longer hospital stays.

Remdesivir, the only only antiviral fully approved for COVID-19 treatment by the Food and Drug Administration, was linked to longer hospital stays in an observational study published in July.

The finding raised some questions about the drug, as it is prescribed in the hopes of shortening recovery times for patients who are hospitalized with COVID-19. However, the fact that the drug is given over a period of five or 10 days may help explain why patients stayed in the hospital longer. Doctors may be keeping patients in the hospital slightly longer to give the full, prescribed regimen, the researchers say, arguing that it may ultimately make more sense to stop use once patients show signs of doing better.

The study also found that there was no association with improved mortality rates, but that conclusion is not new. It’s why the World Health Organization currently does not recommend Remdesivir for patients who are hospitalized with COVID-19.

5. Up to 60% of COVID cases in the United States may have gone uncounted.

A new model published in July suggests that as many as 60% of COVID-19 cases have gone undetected as of this spring.

Using data like case counts and COVID-19 deaths, researchers with the University of Washington developed a statistical framework that attempts to show the real prevalence of COVID-19 throughout the country and in specific states. Their results, published online in the Proceedings of the National Academy of Sciences in July, suggest that about 20% of Americans had COVID-19 by this past March — but only about 1 out of every 2.3 of those cases had actually been confirmed, in part because the amount of testing in states has varied widely.

“Our results indicate that a large majority of COVID infections go unreported,” the authors wrote. “Even so, we find that the United States was still far from reaching herd immunity to the virus in early March 2021 from infections alone.”

And that, the researchers conclude, points to the continued need for vaccination to help reach herd immunity.

Experts are still learning about COVID-19. The information in this story is what was known or available as of publication, but guidance can change as scientists discover more about the virus. Please check the Centers for Disease Control and Prevention for the most updated recommendations.