Tag: COVID Questions

You get the dreaded text: the friend you just met for lunch tested positive for COVID-19. Now you’re left to wonder if you, too, will get sick in the coming days.

But when should you expect symptoms to start if you do get sick? The answer has changed from the earliest days of COVID-19, experts say.

“In the beginning of the pandemic, we were really looking at seven to 10 days as the window of time where people had to quarantine or isolate after an exposure,” says Andrew Pekosz, a virologist at Johns Hopkins University. “That has shortened significantly now.”

How long does it take to develop COVID-19 symptoms?

An incubation period is the length of time it takes someone to develop symptoms after exposure to a pathogen. The incubation period for SARS-CoV-2, the virus that causes COVID-19, has shortened considerably since the virus first began circulating, recent data suggest. Incubation periods averaged about five days when the Alpha variant was dominant, about 4.5 days when Beta and Delta were dominant, and about 3.4 days once Omicron took over, according to a 2022 research review.

Newer research from various countries, including Japan, France, and Singapore, also suggests Omicron strains have incubation periods of about three days, or even a little less.

The virus’ incubation period is likely shrinking for a few reasons, says Shane Crotty, chief scientific officer at the La Jolla Institute for Immunology. The virus has evolved over time, becoming faster and more adept at infecting humans, Crotty says. Nearly everyone has also now had at least one brush with COVID-19, whether through vaccination or illness. Each encounter leaves behind instructions for the immune system, helping it recognize the virus faster the next time it appears.

“You having symptoms is all about your immune system being activated,” Crotty explains. “The whole pre-symptomatic period is bad news because your immune system has not managed to pull the fire alarm yet.” A shorter incubation period means that your body is “recognizing the virus faster and pulling those sprinkler systems faster.”

When should I test for COVID-19 after an exposure, and when am I in the clear?

Federal health authorities, including the U.S. Centers for Disease Control and Prevention, recommend testing no sooner than five days after a COVID-19 exposure, unless you develop symptoms earlier. But since current variants seem to have incubation periods of around three days, Pekosz says it’s appropriate to test as soon as day three, again unless symptoms start earlier.

Dr. Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, says he starts to feel more confident he’s dodged an infection if he’s still feeling healthy three days after a potential exposure. But, “remember, incubation periods are statistical probabilities,” he says. “There’s always going to be outliers.” You could develop a sore throat or runny nose only a couple days after exposure to the virus, or you might not feel sick until day five—or, if you’re lucky, you may not get infected at all.

The timing of symptom onset depends on lots of factors, including the amount of virus to which someone was exposed, Hotez says. Their level of pre-existing immunity may also affect the likelihood or timing of getting sick, Crotty adds.

Given all this variation, Pekosz recommends monitoring your health for up to a week after an exposure and wearing a mask around other people during that time. Remember, too, that false negatives are possible on at-home tests. If you get a negative result, the U.S. Food and Drug Administration recommends taking at least one more test 48 hours later to confirm it.

What is the incubation period of JN.1?

It’s too soon to know exactly, but Hotez says JN.1 is likely to have an incubation period similar to that of other Omicron strains. One 2023 study found that while incubation periods have gotten shorter over time, the various Omicron subvariants’ have all been similar to one another.

In general, Crotty says, there’s a limit to how low incubation periods can go. The SARS-CoV-2 virus works by invading human cells and using them to make numerous copies of itself. SARS-CoV-2 has a long genome that takes a while to copy, so Crotty doubts its incubation period will get much shorter than it already has. Viruses like measles and varicella (which causes chickenpox) on average take longer than a week to incubate, so, by comparison, a three-day incubation period is already pretty fast.

The antiviral drug regimen Paxlovid can be lifesaving for people vulnerable to COVID-19’s worst effects, helping them avoid hospitalization or worse if they catch the virus.

But what about adults who are young and healthy? Is there any reason they should take Paxlovid if they catch COVID-19?

Right now, there’s “no proven benefit” to doing so, and even some potential downsides, says Dr. Roy Gulick, chief of infectious diseases at Cornell University’s Weill Medical College. Here’s what to know.

Do low-risk people benefit at all from taking Paxlovid?

Paxlovid—a five-day course of two different pills—is approved by the U.S. Food and Drug Administration for adults at high risk of developing severe COVID-19, such as those who are elderly, immunocompromised, or have underlying health conditions. (It is also available under emergency-use authorization for adolescents with health conditions that make them susceptible to serious disease.) Paxlovid “absolutely works” for these patients, Gulick says, slashing their chances of being hospitalized or dying and potentially shortening the length of their infections.

But studies suggest that people without risk factors for severe COVID-19 are unlikely to benefit from taking Paxlovid. The serious COVID-19 complications it is designed to prevent—namely hospitalization and death—are already rare among people who are young and healthy, and research from manufacturer Pfizer suggests Paxlovid does little to eliminate routine symptoms among lower-risk people. Based on these findings, Pfizer stopped studying Paxlovid among “standard risk” patients in 2022.

For people who are unlikely to get very sick in the first place, “I don’t know that it adds a whole lot,” says Dr. Cameron Wolfe, an infectious-disease specialist at the Duke University School of Medicine.

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Even in a 2023 study of Canadian adults who all had some risk factors for serious disease, such as age or health problems, the researchers found that Paxlovid’s benefits were strongest among “extremely vulnerable” individuals, and petered out among people who weren’t quite as susceptible to complications.

That said, deciding who is at high risk is not always simple, Wolfe says. Though he is hesitant to prescribe Paxlovid to someone without any risk factors for severe disease, he’s more willing to do so for people in the gray area—such as a person in their 50s with some health concerns, or someone who is young and healthy but nonetheless had a bad prior case of COVID-19. If you think you may benefit from Paxlovid, it’s best to speak with a physician about your specific case, he says.

Does Paxlovid prevent Long COVID?

Some research suggests that high-risk people who take Paxlovid shortly after catching COVID-19 are less likely to later develop Long COVID symptoms. But the same doesn’t seem to be true within the general population, according to a study published in January 2024.

In the new study, researchers compared a group of about 350 vaccinated people who had COVID-19 and took Paxlovid with a group of about 1,250 vaccinated people who didn’t take the antiviral when they were sick. About the same percentage of people in both groups went on to experience Long COVID symptoms: 16% of those who’d taken Paxlovid, and 14% of those who hadn’t.

Are there downsides to taking Paxlovid just to be safe?

About 20% of people who take Paxlovid later experience “rebound” positive tests, according to one recent study—although it’s possible to have a rebound after an untreated case of COVID-19, too.

Paxlovid also comes with side effects including gastrointestinal upset and a bad aftertaste. In addition, it interacts with some other medications, meaning patients may have to stop taking other drugs while they’re on it. “For people who need it, these [drawbacks] can be managed and the balance favors taking it,” Gulick says. “But for people who don’t need it, there are enough negative qualities of the drug that it should be a very carefully considered decision.”

Finally, the federal government stopped offering Paxlovid for free to everyone in the U.S. on Dec. 15, 2023, meaning some people now have to pay for Paxlovid. It remains free for people who are uninsured or on Medicaid or Medicare, and the government has also partnered with digital-health company eMed on a free test-to-treat program available to all adults.

Are other treatments available for people who are young and healthy?

There are other COVID-19 antivirals on the market, including the intravenous drug remdesivir and the pill molnupiravir. But, as with Paxlovid, they’re intended for people at increased risk of getting very sick, and Gulick says there’s no proof that they help people at lower risk. Molnupiravir is also less effective than Paxlovid, Gulick says, while remdesivir is a more invasive option since it must be delivered intravenously in a medical facility.

“There may be other drugs in the future that we might turn to,” Gulick says. But for now, people without specific risk factors for severe disease are best off staying home, resting as much as possible, and using over-the-counter medications to manage symptoms.