When Is COVID Most Contagious?

All eyes are on Omicron HV.1, the newest COVID-19 variant. All COVID variants are infectious, but are some of them more likely to make you sick than others? When are you most likely to spread COVID to someone else if you’re ill?

Here’s what experts say about COVID contagiousness, including when you’re the most likely to spread COVID to other people.

When Is COVID Most Contagious?

The point at which you’re most likely to spread COVID to others—that is, peak infectivity of the virus—varies from person to person, Linda Yancey, MD, an infectious disease specialist at Memorial Hermann Health System in Houston, told Verywell. The crucial factor is symptom onset. That’s the time when you are most contagious.

“You’re passing virus out through your nose into the environment, and you’re passing it to the people in close contact with you,” Sharon Nachman, MD, division chief for pediatric infectious disease at Stony Brook Children’s, told Verywell. “Once you’re sneezing, you are infectious.”

With newer variants like HV.1, there’s currently not enough data to know their peak infectivity. Instead, researchers have to look at the variants we do know about. Based on XBB 1.5—a more transmissible strain that’s better able to evade immunity—peak infectivity was around day four, Thomas A. Russo, MD, a SUNY distinguished professor and chief of the Division of Infectious Disease in the Department of Medicine at the University at Buffalo, told Verywell.

The good news is that infectivity appears to decrease over time. Most—but not all—of us will no longer be infectious by day 10.

Can You Be Contagious If You Don’t Have Symptoms?

Once your symptoms get better, the chances of you getting someone else sick are low—but it’s not impossible. Even people with no symptoms (asymptomatic) can spread the virus. That’s why Nachmann recommends that you keep wearing a mask for another five days after you start feeling better. This step cuts down on transmission risk and protects high-risk people you might be in close contact with.

Are You Still Contagious After a Negative Test?

A negative COVID test post-infection means that you are “probably not contagious at that point,” said Nachman.

If you test negative using a rapid COVID test at home, you can retest within 48 hours to be sure that it’s truly negative. Per the CDC guidelines, you’ll need two negative rapid tests in a row if you want to take off your mask and end isolation early.

Is COVID Less Infectious Than Earlier in the Pandemic?

“I do think that the variants that we have now—some are more infectious and some are less infectious,” said Nachman. For example, strains of Omicron were found to be more transmissible than strains of the Delta variant. But with any introduction of a new virus to a population that has not yet been exposed to it, Nachman said the outcomes would be similar to the first outbreak of the pandemic.

However, since most people have a degree of immunity to the virus—from the vaccine and from getting the virus at some point—the chances of developing an infection are lower. If a person does get sick, the illness is likely to be milder and last a shorter amount of time, said Russo.

How to Protect Yourself From New COVID Variants

Getting vaccinated remains the most effective safeguard against COVID and the complications that can come from getting sick. Getting updated vaccines helps your immune system become better positioned to recognize and attack newer strains of the virus.

Compared to the original vaccines that were rolled out, the current vaccines are “much more updated and a much better match with what’s circulated right now than when we got that version [of COVID] a year ago,” said Russo.

While the vaccines do not guarantee that you won’t catch COVID, “you’re much less likely to develop severe disease and end up in the emergency department or have a bad outcome,” said Russo. 

The CDC recommends updated vaccines for people aged 6 months and older, immunocompromised people, older adults, and people with chronic medical conditions, such as diabetes and heart disease.

“We’re entering the month where hospitalizations are increasing,” underscoring the importance of the updated vaccines,” said Russo. “We have the tools to minimize the consequences of COVID both acutely and with long COVID with the combination of these entities: vaccine, testing early, and antivirals.”

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.