ImageA funeral attendant providing hand sanitizer to a mourner arriving for a visitation in Elsa, Texas.Credit...Tamir Kalifa for The New York Times Federal health authorities issued a formal warning on Wednesday about the dangers of drinking hand sanitizer and alerted poison control centers across the nation to be on the lookout for cases of methanol toxicity after four people died and nearly a dozen became ill. From May 1 to June 30, 15 people in Arizona and New Mexico were treated for poisoning after they swallowed alcohol-based hand sanitizer, the Centers for Disease Control and Prevention said. Three of the patients sustained visual impairments, according to the C.D.C., which said that drinking hand sanitizer can cause methanol poisoning. Methanol is a type of alcohol commonly found in fuel products, antifreeze, industrial solvents and in some preparations of hand sanitizer that federal health officials said is harmful and should not be used. Hand sanitizer has become a ubiquitous and often scarce substitute for hand washing during the coronavirus pandemic. The C.D.C. has recommended the use of ethyl alcohol- or isopropyl alcohol-based hand sanitizer if soap and water are not readily available. “Alcohol-based hand sanitizer products should never be ingested,” the C.D.C. said in the advisory on Wednesday. Updated 2020-08-06T03:36:03.750Z It was not immediately clear if any of the people who were poisoned drank the hand sanitizer for its disinfectant properties. The C.D.C. said some adults had consumed it for its alcohol content. Health officials warned that drinking hand sanitizer made with either methanol or ethanol could cause a headache, blurred vision, nausea, vomiting, abdominal pain, loss of coordination and decreased level of consciousness. Methanol poisoning can additionally result in metabolic acidosis, seizures, blindness and death, they said. “Swallowing alcohol-based hand sanitizer products containing methanol can cause life-threatening methanol poisoning,” the C.D.C. said. “Young children might unintentionally swallow these products, whereas adolescents or adults with history of alcohol use disorder might intentionally swallow these products as an alcohol (ethanol) substitute.” Last week, the Food and Drug Administration, which regulates hand sanitizers, announced that it had placed methanol-based hand sanitizers manufactured in Mexico on an import alert because of their toxicity. It also said it was working with retailers to recall that type of hand sanitizer and remove those products from marketplaces. “Consumers must also be vigilant about which hand sanitizers they use, and for their health and safety we urge consumers to immediately stop using all hand sanitizers on the FDA’s list of dangerous hand sanitizer products,” Dr. Stephen M. Hahn, the agency’s commissioner, said in a statement on July 27. In June, the New Mexico Department of Health announced that three people had died, three were in critical condition and one was permanently blind after ingesting hand sanitizer that contained methanol. The Coronavirus Outbreak › Frequently Asked Questions Updated August 4, 2020 I have antibodies. Am I now immune? As of right now, that seems likely, for at least several months. There have been frightening accounts of people suffering what seems to be a second bout of Covid-19. But experts say these patients may have a drawn-out course of infection, with the virus taking a slow toll weeks to months after initial exposure. People infected with the coronavirus typically produce immune molecules called antibodies, which are protective proteins made in response to an infection. These antibodies may last in the body only two to three months, which may seem worrisome, but that’s perfectly normal after an acute infection subsides, said Dr. Michael Mina, an immunologist at Harvard University. It may be possible to get the coronavirus again, but it’s highly unlikely that it would be possible in a short window of time from initial infection or make people sicker the second time. I’m a small-business owner. Can I get relief? The stimulus bills enacted in March offer help for the millions of American small businesses. Those eligible for aid are businesses and nonprofit organizations with fewer than 500 workers, including sole proprietorships, independent contractors and freelancers. Some larger companies in some industries are also eligible. The help being offered, which is being managed by the Small Business Administration, includes the Paycheck Protection Program and the Economic Injury Disaster Loan program. But lots of folks have not yet seen payouts. Even those who have received help are confused: The rules are draconian, and some are stuck sitting on money they don’t know how to use. Many small-business owners are getting less than they expected or not hearing anything at all. What are my rights if I am worried about going back to work? Should I refinance my mortgage? It could be a good idea, because mortgage rates have never been lower. Refinancing requests have pushed mortgage applications to some of the highest levels since 2008, so be prepared to get in line. But defaults are also up, so if you’re thinking about buying a home, be aware that some lenders have tightened their standards. What is school going to look like in September? It is unlikely that many schools will return to a normal schedule this fall, requiring the grind of online learning, makeshift child care and stunted workdays to continue. California’s two largest public school districts — Los Angeles and San Diego — said on July 13, that instruction will be remote-only in the fall, citing concerns that surging coronavirus infections in their areas pose too dire a risk for students and teachers. Together, the two districts enroll some 825,000 students. They are the largest in the country so far to abandon plans for even a partial physical return to classrooms when they reopen in August. For other districts, the solution won’t be an all-or-nothing approach. Many systems, including the nation’s largest, New York City, are devising hybrid plans that involve spending some days in classrooms and other days online. There’s no national policy on this yet, so check with your municipal school system regularly to see what is happening in your community. A spokesman from the health department said at the time that the cases were related to alcoholism, noting that hand sanitizer was sometimes consumed for its high alcohol content. In 2016, a former Wells Fargo employee drew widespread attention after she told The New York Times that she had been under so much stress at her job during a banking scandal that she drank hand sanitizer and became addicted to it. The rise in poisoning cases of people who drank hand sanitizer drew the attention of public health researchers, who wrote about it in a 2012 report. Dr. Anthony F. Suffredini, a senior investigator at the National Institutes of Health and an author of the report, described the case of a 17-year-old hospital patient who became acutely ill after putting hand sanitizer into his feeding tube while being treated for other medical problems. The boy required mechanical ventilation to assist with his breathing and dialysis to rid his blood of the alcohol. “This young man, who was from the South, mentioned that among his circle of friends, who were all underage, if they couldn’t find alcohol any other way, this was one of the ways they tried to get high,” Dr. Suffredini said at the time.