Why People With COVID Booster Shots Test Positive for Longer

COVID test

Verywell Health / Amelia Manley

Key Takeaways

  • A preprint study found that people who received a booster were more likely to remain positive after five days of symptom onset.
  • Some people might display COVID-19 symptoms before testing positive, which indicates that the immune system can recognize and fight the virus earlier.
  • Experts say there may be a longer gap between symptom progression and peak viral load.

People who are vaccinated and boosted may be more likely to remain COVID-positive after five days of symptom onset if they get sick, according to a preprint study. This means they might still test positive after the five-day isolation period recommended by the Centers for Disease Control and Prevention (CDC).

Michael Mina, MD, PhD, chief medical officer at eMed and co-author of the study, said these results may be misinterpreted to suggest that the COVID-19 vaccines induce a lengthier infection, but this isn’t the case.

Instead, the vaccines prompt the body’s immune system to recognize the virus earlier, so that it can start fighting against the infection right away.

“A fever is actually the human response to try to suppress viral replication because the virus doesn’t like to grow in high temperatures,” Mina told Verywell. “You might get congestion and have a headache. And these are all part of the immunological response, or, or secondary effects of it. But that doesn’t mean that you have a high viral load yet.”

Boosted individuals might recognize their symptoms earlier and start to self-isolate before they’re infectious. But the researchers suggested that there is now a longer gap between developing symptoms and reaching peak viral loads for vaccinated and boosted people.

“You can have symptoms that occur from the immune response, or you can have symptoms occur because the virus is harming you,” he said. “This, unfortunately, got very, very confused by most scientists at the beginning of the pandemic.”

Time Frame of Infectious Period

When people test positive for COVID-19, the progression of their viral loads follows a curve that mimics a mountain with a steep uphill climb, a peak, and a gradual decline at the end, Mina said.

The starting base of the mountain indicates someone’s initial exposure to the virus. Unvaccinated people tend to develop symptoms in the middle of the curve, toward the peak, according to Mina.

But those who are vaccinated often develop symptoms shortly after exposure, as the viral load is on its way uphill. This is because vaccine-induced immunity teaches people to recognize the virus early, which explains the earlier appearance of symptoms, Mina explained.

He added the duration of infectivity remains the same for boosted people, but their body is more alert to the virus. “It’s your immune system that’s creating that awareness, which we should actually see as a good thing,” Mina said.

How To Know If Your COVID-19 Case Is Infectious?

Rapid antigen testing is the best indicator of infectiousness, according to Mina. The darkness of a person’s positive rapid test and the speed at which it saturates imply a person’s level of infectivity. Still, any positive test means that there’s a chance of being able to spread the virus.

Symptoms as a Warning Sign

A positive but asymptomatic COVID-19 case could be more dangerous to public health than someone who is symptomatic but testing negative, Mina said. The former was of particular concern before vaccines were available, he added.

“What would happen is people would become infectious before they had any symptoms, and that was a massive problem,” Mina said. “About half of the people never developed symptoms and they still were able to transmit. And that’s because their immune system never had a chance to really turn on.”

Before people had access to vaccination, any display of symptoms was extremely dangerous, Mina added. “It was literally the symptoms of the virus destroying you,” he said.

COVID-19 remains a deadly virus and its symptoms are still not something to be taken lightly. However, at least 66% of the U.S. population is now fully vaccinated and many have developed some form of natural immunity.

As a result, mild COVID-19 symptoms show that our immune system is working to protect us. “Now, our body doesn’t have to wait until the virus is really doing damage to us, for us to recognize, ‘I might be infected,’” Mina said.

What This Means For You

COVID-19 symptoms may occur for different reasons, one being that your body is fighting the virus and the other being that the virus is hurting you. Experts say a quick way to know if your symptoms are part of a transmissible infection is to take a COVID-19 rapid antigen test.

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.

1 Source
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Landon E, Bartlett A, Marrs R, Guenette C, Weber S, Mina M. High rates of rapid antigen test positivity after 5 days of isolation for COVID-19. medRxiv. Preprint posted online February 2, 2022. doi:10.1101/2022.02.01.22269931

By Claire Wolters
Claire Wolters is a staff reporter covering health news for Verywell. She is most passionate about stories that cover real issues and spark change.