Is It Allergies or a Breakthrough Infection?

Photo: Noam Galai/Getty Images

COVID-19 cases are back on the rise in the U.S., and as vaccination rates hover around 50 percent, a new and potentially scary concern is emerging: breakthrough infections. Breakthrough infections occur when a fully vaccinated person gets the coronavirus. The CDC stopped tracking breakthrough cases that weren’t severe enough for hospitalization in May, so it’s also difficult to tell exactly how common they are — but the anecdotal reports can be alarming. Wasn’t the whole point of the vaccine to protect people from getting COVID-19? According to experts, not exactly.

Turns out, there are a few misleading numbers around breakthrough infections. To start with, they’re still extremely rare: The New York Times estimates that a vaccinated person’s chances of getting a breakthrough infection are one in 5,000.

Plus, as more people get vaccinated, the number of breakthrough infections is going to increase just because there’s a higher number of vaccinated people. So far, only a few states have actually reported an increase in serious breakthrough cases, but the fact that they’re going up isn’t necessarily a bad sign. The experts we spoke with said the most useful number is the portion of people hospitalized with COVID-19 who are vaccinated. Out of all COVID-19 hospitalizations, a Times analysis found that, depending on the state, vaccinated patients made up 5 percent or less of that population.

This is all pretty promising data, suggesting that even if our vaccines don’t always prevent us from getting COVID, they do largely prevent us from experiencing serious or life-threatening symptoms. Since May, the CDC has reported that of the more than 171 million vaccinated Americans, only about .006 percent have ended up hospitalized with COVID.

Still, trying to figure out whether your scratchy throat is the result of allergies or a breakthrough case — and what you should do next — is stressful. Here’s what you need to know.

Breakthrough Cases Are Going to Happen

The first thing to know about breakthrough infections is that they’re generally expected with a new vaccine. “Vaccines aren’t bug zappers or force fields,” says Amesh Adalja, an infectious-disease doctor at Johns Hopkins University. Vaccines are designed to prevent serious disease, hospitalization, and death, and that’s exactly what they’re doing so far.

Part of the reason breakthrough cases have gone up is also because transmission is so high right now. “Delta is pushing up the overall case number,” says Emily Martin, an epidemiology professor at the University of Michigan. “It’s creating more infected people around, so more opportunities to find any gaps in vaccine protection.” So far, studies are still showing the vaccine provides high protection against the Delta variant — there’s just more of it around, so we’re going to see some spread to vaccinated people.

How to Know If You Have a Breakthrough Infection

The most common symptoms of breakthrough infections are headache, runny nose, sore throat, loss of smell, and sneezing (that last one is a new symptom of the Delta variant). As with COVID in general, the symptoms of a breakthrough infection can be difficult to differentiate from everyday ailments like common colds or even allergies. Some experts believe breakthrough infections are actually being underreported, because the symptoms are so mild people don’t even think to get a test, or mistake it for a cold — and because the CDC stopped tracking breakthrough cases that didn’t require hospitalization, we can’t know exactly how many there are.

Identifying COVID-19 will ultimately depend on being vigilant and getting tested frequently. Peter Chin-Hong, an infectious-disease specialist and doctor at University of California San Francisco, recommends having “a very low threshold for testing.” It’s also worth taking context into account: If you’re in a current hot spot or engaging in higher-risk activities, like going to bars that aren’t checking vaccine cards, a bout of sniffles is probably reason enough to get a test. If you’ve been in full quarantine mode, the same symptoms are much less likely to be an infection. If you’ve done something higher risk and are worried about being infected, there’s no downside to getting tested, even if you don’t have symptoms. 

If You Do Have a Breakthrough Infection

So far, the vaccines are holding up when it comes to preventing infected COVID-19 patients from experiencing serious or life-threatening symptoms. Breakthrough cases are generally gentler and shorter than infections in unvaccinated people: Anecdotal reports range from a scratchy throat to, more rarely, loss of taste and brain fog, but studies have found vaccinated people experience symptoms for much less time. Experts also say there’s a relatively low likelihood of having long COVID with a breakthrough infection, since it tends to be linked to the severity of the disease. And for the most part, vaccinated people don’t need to worry about ending up in the hospital, Chin-Hong says. The most serious hospitalizations are occurring with severely immunocompromised patients and elderly people, whose immune systems don’t respond as strongly to a vaccine.

Even if you’re not likely to need hospitalization, you’ll still want to take precautions to avoid spreading the infection. Vaccinated people can spread COVID-19 just as easily as unvaccinated people, so the CDC guidance is the same for both: Isolate for ten days after the symptoms first show up. If you’ve been in contact with someone who was infected, the quarantine period is shorter if you have the vaccine: three to five days, and if you test negative after that time, you’re in the clear.

Breakthrough Infections Shouldn’t Send Us Back to Full Quarantine Mode

While reinstituting mask mandates in public spaces is going to be vital to minimizing the spread, keep in mind that the existence of these breakthrough cases doesn’t mean you have to go back to Zoom happy hours and friend pods. There’s no hard and fast rule, but the best course of action, Chin-Hong says, is to use your best judgment when it comes to socializing. He says he’s taking into account a few factors, like whether the people he’s interacting with are vaccinated and if he trusts that they use their masks in crowded indoor spaces. For people with unvaccinated children or higher-risk people at home, masking in public spaces is key to making sure you and everyone you live with stays protected. Martin also recommends considering the current COVID-19 rates in your area. “Even if vaccinated people have a small chance of getting infected, that chance gets bigger when you have a lot of transmission in your local community,” she says.

The best thing you can do to keep everyone safe is to encourage as many people as you can to get vaccinated. “The vaccine keeps us out of the hospital,” Chin-Hong stressed. And even if new evidence shows that vaccines may become less effective at preventing infection over time, the numbers on preventing hospitalization have not wavered.

This post has been updated.

Is It Allergies or a Breakthrough Infection?