After being infected with COVID-19, how long are you protected with antibodies and when could you get the virus again?
Though the questions have been asked over the past two years, the answers have changed as new variants are discovered and the latest findings are revealed.
The omicron variant, for example, led to a major shift in "natural immunity," with many who had previously been infected susceptible to reinfection with the new version of the virus.
Now, as omicron makes up nearly all U.S. COVID cases, it's a question of how protection from one version of omicron will work against newer subvariants.
"At the beginning, we could very confidently, you know, sort of back in February, we could really confidently say that 90% of the people were not getting reinfected if they had COVID already," Chicago Department of Public Health Commissioner Dr. Allison Arwady said last month. "That's been dropping a little bit though around the world."
According to the Centers for Disease Control and Prevention, "after recovering from COVID, most individuals will have some protection from repeat infections."
"However, reinfections do occur after COVID-19," the CDC states, adding that changes and mutations "can lead to the emergence of variants that can increase the risk of reinfection."
Last month, Chicago's top doctor said experts were seeing changes in immunity from infection, noticing more breakthrough infections and natural immunity not lasting.
"So we know that when somebody has had COVID, it's as much about how recently they've had it in some ways, because we are still seeing pretty good protection if somebody had one version of omicron," Arwady said. "But we are starting to see, as omicron has continued to evolve, we're starting to see some more people who had original omicron even in December, even getting some of these these new subvariants of omicron."
BA.4 and BA.5 are among those subvariants, or “sublineages,” of the omicron COVID variant, with the CDC also tracking BA.2.12.1, BA.2, B.1.1.529 and BA 1.1, among others.
In the Midwest, BA.5 makes up 8.1% of cases and BA.4 is 6.5%.
And while BA.2.12.1 makes up a majority of cases across the country and in Illinois and Chicago still, White House COVID-19 coordinator Dr. Ashish Jha told NBC News BA.4 and BA.5 will likely be dominant in the U.S. by the end of the summer or early fall.
Aside from being even more contagious than previous variants, scientists are tracking a mutation in BA.4 and BA.5 that could help it evade some immunity and cause reinfections.
A genetic trait that harkens back to the pandemic's past, known as a “delta mutation," appears to allow the BA.2.12.1 subvariant "to escape pre-existing immunity from vaccination and prior infection, especially if you were infected in the omicron wave," said Dr. Wesley Long, a pathologist at Houston Methodist in Texas. That's because the original omicron strain that swept the world didn’t have the mutation.
The genetic change is also present in the omicron relatives BA.4 and BA.5. Those have exactly the same mutation as delta, while BA.2.12.1 has one that's nearly identical.
This genetic change is bad news for people who caught the original omicron and thought that made them unlikely to get COVID again soon.
Although most people don't know for sure which variant caused their illness, the original omicron caused a giant wave of cases late last year and early this year.
Long said lab data suggests a prior infection with the original omicron is not very protective against reinfection with the new mutants, though the true risk of being reinfected no matter the variant is unique to every person and situation.
Chicago's data showed that last week, reinfections made up about 10% of new COVID cases, an increase from recent months, though health officials said many of the recent reinfections were in residents who contracted COVID some time ago, prior to the omicron wave.
In a twist, however, those sickened by delta previously may have some extra armor to ward off the new mutants. A study released before it was reviewed by other scientists, by researchers at Ohio State University, found that COVID patients in intensive care with delta infections induced antibodies that were better at neutralizing the new mutants than patients who caught the original omicron.
“The omicron infection antibody does not appear to protect well against the subvariants compared to delta,” said Dr. Shan-Lu Liu, a study author who co-directs the viruses and emerging pathogens program at Ohio State.
But Liu said the level of protection a delta infection provides depends partly on how long ago someone was ill. That's because immunity wanes over time.
People who got sick with delta shouldn’t think of themselves as invulnerable to the new subvariants, especially if they’re unvaccinated, Long said. “I wouldn’t say anyone is safe."
A recent study from Northwestern Medicine showed that many so-called COVID "long-haulers" continue to experience symptoms including brain fog, tingling, headaches, dizziness, blurred vision, tinnitus and fatigue an average of 15 months after the onset of the virus.
"Long-haulers,” are defined as individuals who have had COVID symptoms for six or more weeks, the hospital system has said.
But, according to the CDC, four weeks after infection is when post-COVID conditions could first be identified.
"Most people with post-COVID conditions experienced symptoms days after their SARS CoV-2 infection when they knew they had COVID-19, but some people with post-COVID conditions did not notice when they first had an infection," the CDC states.
Long-COVID symptoms can range from a wide variety of ailments, some of which may even disappear and then return later.
"Post-COVID conditions may not affect everyone the same way. People with post-COVID conditions may experience health problems from different types and combinations of symptoms happening over different lengths of time," the CDC reports. "Most patients’ symptoms slowly improve with time. However, for some people, post-COVID conditions may last months, and potentially years, after COVID-19 illness and may sometimes result in disability."
Testing can also become challenging for such groups as PCR tests can "stay positive for some time," experts said.
"Those PCR tests are very sensitive," Arwady said. "They keep picking up dead virus in your nose for sometimes for weeks, but you can't grow that virus in the lab. You can't spread it but it can be positive."
According to the CDC, some people who contract COVID can have detectable virus for up to three months, but that doesn't mean they are contagious.
Public health officials recommend that even those who contract COVID remain up-to-date with their vaccinations and booster shots.
"I think realistically, this is a guess, but my guess - where we're heading, given that there's no sign yet that COVID has stopped mutating...we've got to keep it from turning into hospitalizations and deaths, which are actually pretty good at already between vaccines and treatments," Arwady said. "But I do think it's likely that in the fall, we probably will see an updated version of a booster that actually has been changed to be more protective against the ways in which COVID has mutated since then."
Get the latest news on COVID-19 in your inbox. Click here to sign up for our daily coronavirus newsletter.