The Moneyist: Why do I need to wear a mask if I’ve had COVID-19? Who is it protecting? Can I really be reinfected?

The Moneyist:My sister became my late father’s power of attorney, took out a reverse mortgage on his home, and drained his equity. What can I do?

Dear LeRoy,

Yes, you can. A recent study in the New England Journal of Medicine concluded that health-care workers in the U.K. who tested positive for immunoglobulin G (IgG) antibodies were protected against the coronavirus for the subsequent six months. But some people, it found, could become re-infected after that, so health professionals ask everyone to wear a mask.

“The extent to which previously infected people are protected from a second infection is uncertain. Understanding whether post-infection immunity exists, how long it lasts, and the degree to which it may prevent symptomatic reinfection or reduce its severity has major implications for the SARS-CoV-2 pandemic,” the study found. Immunity may wane more quickly in some people.

Another reason: If one person doesn’t wear a mask, it could create a domino effect that leads someone else to relax their practice, and another and another. They may not know you had the virus less than six months ago, and it could result in other people being infected. Masks also help to act as a deterrent against touching your face, and remind people that the pandemic isn’t over. (It’s also flu season.)

Related: ‘The attack rate is relatively high as there’s no immunity to it.’ Why coronavirus was never going to be just another flu

The Centers for Disease Control and Prevention have said they’re still evaluating reinfection risks. Reinfection is relatively rare, but it has happened, and the virus continues to spread and develop new mutations, some of which have been more contagious than previous strains. If you want people to get back to work and the economy to recover, wear a mask and practice social distancing.

William Haseltine, a scientist, biotech entrepreneur and infectious disease expert, wrote for Project Syndicate: “We should assume that none of the vaccines under development will prevent infection or provide lifelong, lasting immunity. At best, they will limit the symptoms of those infected and minimize the number of COVID-19 cases that progress to severe illness.”

“China showed that new infections could be halved in just two weeks through standard measures such as enforced mask-wearing, social distancing, and mandatory quarantine and isolation,” he added. “By contrast, in countries like Brazil, the United Kingdom, and the United States, national political leaders dismissed the threat and dithered in marshaling the appropriate response.”

Wear your mask. Keep yourself and others safe.

The Moneyist:My wife and I have 3 kids. I also have 3 kids from a previous marriage. How should we split our house among these 6 children?

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Quentin Fottrell is MarketWatch’s Moneyist columnist. You can email The Moneyist with any financial and ethical questions at qfottrell@marketwatch.com. By emailing your questions, you agree to having them published anonymously on MarketWatch.