After New York Times writer Melinda Wenner Moyer's daughter tested positive for the coronavirus, she assumed the whole family would "finally" get Covid-19. However, no one else in the family tested positive—even after they started experiencing "classic" Covid-19 symptoms.

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An exposed family never tests positive

On a Sunday evening, Moyer's daughter developed a fever. The following morning, they received an email from her school informing them that she had been exposed to the coronavirus just a few days earlier. 

When Moyer gave her daughter a rapid antigen test, it quickly gave them a positive result. "I resigned myself to the possibility that the whole family was, finally, going to get Covid-19," Moyer writes. "But we didn't — not exactly."

The day her daughter initially tested positive, Moyer's 11-year-old son said he did not feel well and started experiencing "classic" Covid-19 symptoms, including headache, fatigue, sore throat, and runny nose.

Two days later, her husband developed a sore throat and stuffy nose as well. However, "despite testing daily for seven days straight, my husband and son never tested positive for Covid-19 — including on PCR tests administered on my son's fifth day of symptoms, and my husband's third," Moyer writes.

Moyer never tested positive for the virus or developed any symptoms herself.

"We racked our brains as to what might have happened," Moyer writes. She wondered if her husband and son were infected even though they never tested positive. In addition, she wondered whether they had a different virus with similar symptoms—a scenario their pediatrician said was unlikely.

Asking the experts

In search of answers, Moyer called experts in immunology, microbiology, and virology.

One of the first things experts asked was whether the entire family had been vaccinated. Moyer and her husband are vaccinated and boosted, and their children have been vaccinated but not yet boosted.

According to Gigi Gronvall, an immunologist at the Johns Hopkins Center for Health Security, this is relevant because, when you are exposed to the coronavirus, "your immune system kicks into action a lot faster if you're vaccinated versus not vaccinated." This rapid response impacts everything that follows.

"First, the swift immune reaction slows the rate of viral reproduction and spread," Moyer writes.

"This is what the vaccines are there for — to educate your immune system so that it gets a jump on the invaders before they are able to replicate out of control," Gronvall said.

Since the virus does not replicate as quickly in vaccinated individuals, they may be less likely to test positive for the virus after they have been exposed, largely because their immune system "keeps the viral load below the level of detection," said Juliet Morrison, a microbiologist at the University of California, Riverside.

"It's possible, then, that my husband and son did catch Covid-19, but their vaccinated immune systems fended off the infection so well that they never had enough viral proteins in their nose or throat to test positive," Moyer notes. According to Morrison, their string of negative tests likely meant that they were never highly contagious.

Still, Moyer wondered why her husband and son felt sick if they never tested positive. Even if a vaccinated person does not have high levels of the virus in their body, they can still experience powerful Covid-19 symptoms, the experts told Moyer.

This occurs because many symptoms, including fever, malaise, runny nose, and fatigue are actually triggered by the immune system's response to the virus—not the virus itself, Gronvall noted.

According to Morrison, Moyer may have felt fine because her immune system likely fought off the virus so quickly that she never had a chance to feel sick. "It sounds to me like you were definitely exposed," Morrison said.

The experts said Moyer may have had high levels of vaccine antibodies or immune cells that were able to detect and kill the virus before it reached the parts of her immune system that would trigger symptoms.

"All this said, nobody really knows what happened to me, my son or my husband," Moyer writes.

Explaining different reactions to the virus

When trying to understand how Covid-19 affects the body, "there are so many open questions," said Raul Andino, a virologist at the University of California, San Francisco. Different individuals can have very different experiences for a variety of reasons.

For example, Andino noted, it is possible that the virus was replicating in parts of Moyer's husband's or son's body that the tests didn't reach.

"Research suggests that the coronavirus can replicate in the pancreas, heart, brain, kidneys and other organs, although vaccination may reduce the chance that the virus spreads outside the respiratory system," Moyer writes.

"My family is not the only one that has had the bizarre experience of developing coronavirus symptoms but repeatedly testing negative," Moyer notes.

According to Andino, he and his colleagues have been conducting studies that follow and repeatedly test entire households after anyone in the household tests positive for the virus. "What we see is exactly what you described — that some people in the household don't test positive," even though they have symptoms, he said.

Ultimately, "[t]here's a difference between never testing positive and not yet testing positive," Moyer writes. "[M]any people only test for a couple of days and, frustratingly, you can't make clear conclusions from just a couple of negative tests." (Moyer, New York Times, 6/6)