Why People Who Think They Have Immunity From COVID Are Getting It Again

Not long ago, people who recovered from COVID-19 felt confident that natural immunity would protect them from another case for at least six months, if not more. Vaccinated individuals, and especially those who'd received one or two booster shots, were equally sure that if they came down with the virus, the effects would be extremely mild (maybe some sniffles or headaches, maybe not), and afterward, they'd benefit from an extended stretch of natural immunity, too.

But the Omicron surge that first swept over Colorado in late 2021 and early 2022 has changed everything. Over the past few months, the original strain, technically known as B.1.1.529, has splintered into at least four subvariants currently being monitored by the Colorado Department of Public Health and Environment, shorthanded as Omicron 2 (BA.2), Omicron 3 (BA.2.12.1), Omicron 4 (BA.4) and Omicron 5 (BA.5). During that same period, an increasing number of Coloradans have caught COVID-19 a second time mere weeks after seemingly returning to full health; vaccinated and boosted individuals have also gotten quite ill, though relatively few have required hospitalization.

As a result, health officials are fielding a new series of questions about COVID. Do people who'd been infected by the original Omicron strain have no immunity from its subvariants? And are those subvariants resistant to the vaccine and the boosters, leaving Coloradans who thought they'd be protected for the long haul just as vulnerable as those who didn't bother to roll up their sleeves?

Brian Spencer, spokesperson for Colorado's joint information center, which is handling communication about COVID-19 for the state, admits that definitive answers are still a ways off.

"The Omicron lineage overall has been shown to be more transmissible than previous COVID-19 variants, and it is partially able to evade protection conferred by prior infection with other variants," Spencer acknowledges, then adds: "While we are seeing increasing numbers of cases, we believe immunity to COVID-19 is strong throughout the state, and we are currently still within modeling estimates that would generate a significantly smaller peak in the coming weeks than we have seen in some recent waves."

In the meantime, he says, "We are still learning more about how the different Omicron subvariants behave and the risk of reinfection and breakthrough infection for Coloradans with prior infection or vaccination."

Given this uncertainty, the CDPHE recommends sticking with the tried and true. "The best protection against all variants of COVID-19 is to get vaccinated with all recommended doses of the lifesaving COVID-19 vaccine," Spencer says. "Anyone, regardless of vaccine status, who experiences symptoms should get tested immediately and isolate while waiting for test results. People who have COVID may be able to get treatment to help recovery and avoid severe illness."

But those who are lucky enough to avoid COVID's worst impacts shouldn't treat the malady like an annoying summer cold. "If you have been around someone who has COVID-19, you might need to quarantine," Spencer stresses. "Quarantine involves staying at home and away from other people for five days after your last exposure to someone who has COVID-19, then wearing a mask in public for five more days. If you have tested positive for COVID-19 or have symptoms of COVID-19, you should isolate. If you are able to stop isolating after five days, you should avoid high-risk people and settings and wear a mask around others in your home and in public for five more days after that.

"Anyone participating in in-person gatherings can also consider rapid-testing themselves and other attendees before an event to reduce the risk of transmission, especially if you have household or other close contact with someone who is at high risk for severe disease," he adds. "If you or your family member are at high risk for severe illness, wearing a mask can offer greater protection in public indoor spaces."