What we know about COVID-19 seems to change by the minute.
It’s understandable, given the massive scale of the pandemic. More than 437 million cases have been confirmed around the world since tracking began. And even now — after two full years living with the coronavirus — the virus and ways to address it are still relatively new to the medical world, so researchers are learning as they go.
Still, the amount of information about the coronavirus is dizzying. It’s hard to keep track of what’s known, what’s a myth and which guidance we should follow. That’s why HuffPost has rounded up five of the most important new things we learned about COVID-19 in February.
1. The Pfizer vaccine is less effective at preventing omicron infections in kids 5 to 11
In late February, we got new data about how well the Pfizer vaccine — the only COVID vaccine approved for children ages 5 to 11 — held up in that age group during New York City’s omicron surge. Unfortunately, that data suggests the vaccine was much less effective at preventing infection in 5- to 11-year-olds, who receive a much smaller dose than adolescents, teens and adults. Estimated vaccine effectiveness dropped from 68% to just 12% six weeks later, the study found.
Still, it is critical to keep in mind that the vaccine remained protective against severe disease, the researchers wrote. Also, the overall risk of hospitalization among children remains low. Between 0.1% and 1.5% of current COVID infections nationally result in hospitalization, according to the most recent estimates.
Still, the researchers who conducted the study argue their findings highlight an urgent need to keep studying — and potentially tweaking — vaccine dosing for young children. Trials for children under 5, using smaller doses of the Pfizer shot, are still ongoing. Kids that age are not yet eligible for COVID vaccines.
In the meantime, the researchers emphasized that a layered approach to prevention — one that includes mask-wearing in public settings — is key.
2. The virus likely originated in a Wuhan market, not a lab
The origins of the SARS-CoV-2 virus have been a source of controversy and political strife since the start of the pandemic. But two preliminary research papers released last month strengthen the case that the virus originated in the Huanan Seafood Wholesale Market in Wuhan, China — not in a lab. These papers have not yet been subjected to peer review, so they should be regarded with caution.
Still, as The New York Times was the first to report, the researchers analyzed virus genes, maps of the market and social media activity of the earliest COVID-19 patients in the area. All of that evidence suggests the virus was present in live animals sold at the market and “spilled over” into people who worked or shopped there.
While many experts caution that we still do not know definitively how the virus initially spread, the papers add to growing evidence that points to live animals, not human engineering. Ultimately, understanding the origins of SARS-CoV-2 is important because it may help prevent future pandemics, experts say.
3. Reinfection is possible with ‘omicron 2.0’ — but it’s rare
Public health experts have largely provided a reassuring view of risks associated BA.2, the relatively new omicron variant that appears even more transmissible than the previous strain and that could become the dominant variant in the United States. Initial reports show that it is not more likely than the initial omicron variant to cause severe illness or death.
Yet data published in February suggests that people who’ve been infected with the initial omicron strain are at risk of reinfection from BA.2 — sometimes not long after their initial infection. Researchers in Copenhagen looked at a pool of 187 people who’d been reinfected with COVID and found that 47 had been infected with BA.2 less than two months after they’d gotten BA.1. Most of the cases were in young, unvaccinated people and resulted in mild illness.
“Omicron BA.2 reinfections do occur shortly after BA.1 infections,” the researchers wrote, “but are rare.”
Also, though reinfection is certainly possible, it’s important to remember that measures that helped protect people against earlier versions of the virus — like vaccines, masking and social distancing — continue to be effective now.
4. People’s risk of mental health disorders may increase after COVID
A study published in the journal BMJ in February found that people who had COVID were 35% more likely to develop anxiety disorders, and were approximately 40% more likely to experience depression or sleep disorders within the year after their diagnosis. They were also more likely to grapple with alcohol dependence and opioid use.
The reasons why aren’t fully understood. There is an established, bidirectional link between severe COVID and certain mood disorders, so people who have those disorders are at greater risk of severe illness, and those with severe illness are at greater risk of mood issues after the fact. The psychological toll of the pandemic itself and of dealing with symptoms are believed to play a role.
But experts increasingly believe COVID may have a direct impact on the brain, disturbing certain pathways that can contribute to mental health disorders.
5. Risk of heart disease increases after even mild infection
An unsettling paper published in February found that people’s risk of heart disease climbs for at least a year after COVID infection, even for those who have relatively mild cases.
Notably, the study found that the risk increased in people under age 65 (who in general are at lower risk of heart issues) and in those who don’t have other risk factors, like obesity or diabetes.
“It doesn’t matter if you are young or old, it doesn’t matter if you smoked, or you didn’t,” study co-author Ziyad Al-Aly of Washington University in St. Louis, warned in Nature. “The risk was there.”
The new study is far from the first to show that COVID infection can hurt the heart in the months after infection, although experts have not gone so far as to recommend that heart screenings become a routine part of follow-up care for those infected with the virus.
Still, it is important to be on the lookout for red flags. According to the American Heart Association, those can include “increasing or extreme shortness of breath with exertion, chest pain, swelling of the ankles, heart palpitations or an irregular heartbeat, not being able to lie flat without shortness of breath, waking up at night short of breath, lightheadedness or dizzy spells.”
Experts are still learning about COVID-19. The information in this story is what was known or available as of publication, but guidance can change as scientists discover more about the virus. Please check the Centers for Disease Control and Prevention for the most updated recommendations.