After covid-19, how immune is the person to the virus? 1:20
(CNN) - Shelby Hedgecock thought a negative test for covid-19 would mean that she had recovered from her initial infection. But three months and another positive test later, he still feels bad, he told CNN.
"I have neurological problems, cognitive problems, word-linking problems," he told CNN's Chris Cuomo on Wednesday. "It is everywhere and I am incredibly tired."
As health experts work to control the virus, stories like those of Hedgecock raise concerns about whether people can be reinfected and whether collective immunity is possible.
Hedgecock tested positive for the coronavirus for the first time on April 20. On May 9, he tested negative, he said.
Almost two weeks later, an oral and nasal swab test was done. The oral test was negative, but the nasal test was positive.
A week later, another test was negative, he said.
And he still has some symptoms, he added. Any effort can take her to bed for days, and she is now taking medication for daily headaches, she explained.
It is unclear whether the second positive test means that Hedgecock became infected again. It is possible that he initially received false negative results or that the positive was misleading, said CNN chief medical correspondent Sanjay Gupta.
"We are not yet receiving documented cases of reinfections ... That does not mean they will not come," Gupta said. "If people lost their immunity, I think now, six months after this, we would be seeing significant amounts of reinfection."
Some types of coronavirus tests have a false negative rate of 15-20%, he told Cuomo on Wednesday.
"If that's the case, then people have been walking around with a false sense of security for a long time," said Hedgecock. "And that is a problem".
The positive test after infection could come from testing for genetic material from the virus, Gupta said. The identified genetic material could be a sign that the virus is present, or it could be remains that the virus left behind, he said.
"We are all learning," said Gupta.
Recent studies have investigated immunity after coronavirus infection.
"These (studies) are very important to the future of this epidemic," Dr. William Haseltine, a former professor at the Harvard Medical School and the Harvard School of Public Health at OutFront, told Erin Monday.
Haseltine said a recent study that found that people who have been infected with the new coronavirus could see that their immunity declines in a matter of months is simply "what we feared."
If the results turn out to be true, Haseltine said, they could have implications for infected people, for the idea of achieving collective immunity against the virus and for the development of a vaccine.
CNN's Andrea Kane contributed to this report.
Collective immunity