Advice is evolving along with the coronavirus. Here's the latest from staff and wire reports.

What's the latest?

More than half of Minnesota seniors are up to date with COVID-19 vaccinations for the first time in months. COVID hospitalizations have doubled in the past two months.

Flu and COVID infections got worse over the holidays, with more misery expected, the CDC said. Health experts offer tips on staying healthy.

Does COVID prefer the gut now? JN.1 is fastest-growing variant to emerge in past two years.

Omicron, now two years old, has proved to be not only staggeringly infectious, but an evolutionary marvel. Read more here.

A quick refresher on how to navigate the pandemic.

A team of scientists is proposing a new explanation for some cases of long COVID, based on their findings that serotonin levels were lower in people with the complex condition.

People who had chills, fatigue, headache and malaise after the second dose of a COVID vaccine had more antibodies against the coronavirus at one month and six months after the shot, compared with those who did not have symptoms, according to a new study.

The death toll from COVID in Minnesota has reached 15,000 people.

What Minnesotans should know about the new COVID-19 vaccine, targeted to the omicron descendant XBB.1.5.

The Defense Department will buy an Edina firm's drug for radiation exposure that could also treat long COVID.

Mayo Clinic is reporting an additional benefit of vaccination beyond protection from COVID-19 infection — a lower likelihood of severe symptoms if people end up with long COVID.

Some people who experience cognitive issues after long COVID continue to struggle with brain function for at least two years, a new study shows. Research shows a majority of people experiencing long COVID symptoms have reported brain fog — a collection of symptoms, including impaired attention, concentration, memory and processing speed. Read more here.

A study published in the scientific journal Nature suggests people with a specific version of a gene were far more likely to experience an asymptomatic infection than those without. The relevant set of genes is known as the human leukocyte antigen, or HLA. Read more here.

The antidiabetic drug metformin, which the University of Minnesota targeted early in the pandemic as a treatment for COVID-19, reduced risks of long COVID in a study. Read more here.

Where can I get tested for COVID-19?

Minnesota is offering eight free at-home rapid COVID-19 tests a month while supplies last online or by calling 1-833-431-2053. Health care providers and some pharmacies offer testing. The Biden administration is making four rapid virus tests available per household free through covidtests.gov. You may find home rapid tests at pharmacies including Walgreens and CVS, grocery stores, health care providers and online.

Where can I see Minnesota COVID-19 updates?

See Minnesota's weekly pandemic update with new numbers Thursdays at 11 a.m.

How do I get antiviral treatments?

Minnesota has a free telehealth option for people with COVID-19 to hasten access to antiviral treatments. Patients download the Cue app on mobile devices to schedule virtual visits with Minnesota-licensed providers, and they can use any COVID-19 test.

Where can I get a vaccine?

Check the state of Minnesota's vaccine page or vaccines.gov. The white COVID-19 vaccination cards are being phased out, now that vaccines are not being distributed by the federal government.

How can I make a COVID-19 vaccine appointment for kids in Minnesota?

Minnesota has a webpage (mn.gov/vaxforkids) to help parents and guardians find a vaccine and answer questions. U.S. regulators cleared doses of the updated COVID-19 vaccines for children younger than age 5. Read CDC vaccine advice here.

What should I do if I've been exposed?

The CDC said anyone exposed — regardless of vaccination status — should get tested five days later, if possible. It said quarantining at home is not necessary, but urged people to wear a high-quality mask for 10 days. Read more here.

If you were exposed to COVID-19 and don't have symptoms, take three home tests instead of two to make sure you're not infected if you test negative, according to new U.S. recommendations.

If you have COVID-19 symptoms, test again 48 hours after the first negative test. If you get a negative result on the second test and you are concerned that you could have COVID-19, you may choose to test again 48 hours after the second test, consider getting a laboratory molecular-based test or call your health care provider. Read more here.

What should I do if I test positive for COVID-19?

The CDC said people who test positive should isolate from others for at least five days, regardless of whether they were vaccinated. If you live with other people, that means staying in a separate room and using a separate bathroom, if possible. You should also wear a mask if you come into contact with others.

You should get care if you have trouble breathing or develop other serious symptoms. But there are many people with certain conditions — including heart diseases, diabetes and weakened immune systems — who should seek care even if they have mild illness, because of their elevated risk for developing serious complications. You should tell your doctor, who may prescribe medications. Tell the people you've been in close contact with.

People with symptoms during isolation, or who develop symptoms during quarantine, are encouraged to stay home.

CDC officials advise that people can end isolation if they are fever-free for 24 hours without the use of medication and they are without symptoms or the symptoms are improving. The CDC said people should wear masks everywhere for the five days after isolation ends.

The CDC cited evidence showing that people with the coronavirus are most infectious in the two days before and three days after symptoms develop.

How does getting vaccinated affect the menstrual cycle?

A study of nearly 20,000 people around the world shows that getting vaccinated against COVID can change the timing of the menstrual cycle. Vaccinated people experienced, on average, about a one-day delay in getting their periods, compared with those who hadn't been vaccinated.

What is the Novavax vaccine?

Novavax shots — used in Australia, Canada, parts of Europe and dozens of other countries — are a protein vaccine that's made with a more conventional technology than the other U.S. options. Protein vaccines have been used for years to prevent other diseases including hepatitis B and shingles.

How do variants work?

At first, SARS-CoV-2 followed the slow and steady course that scientists had expected based on other coronaviruses. Its evolutionary tree gradually split into branches, each gaining a few mutations. Evolutionary biologists kept track of them with codes.

But then one lineage, initially known as B.1.1.7, defied expectations. When British scientists discovered it, in December 2020, they were surprised to find it bore a unique sequence of 23 mutations. Those mutations allowed it to spread much faster.

Within a few months, several other worrying variants came to light around the world — each with its own combination of mutations, each with the potential to spread quickly and cause a surge of deaths. To make it easier to communicate about them, the WHO came up with its Greek system. B.1.1.7 became alpha.

Alpha came to dominate the world, whereas beta took over only in South Africa and a few other countries before petering out. Beta did not descend from alpha. Instead, it arose with its own set of new mutations from a different branch of the SARS-CoV-2 tree. The same held true for all the Greek-named variants, up to omicron.

It's likely that most of these variants got their mutations by going into hiding. Instead of jumping from one host to another, they created chronic infections in people with weakened immune systems. These victims harbored the virus for months, allowing it to accumulate mutations. When it eventually emerged from its host, the virus had a startling range of new abilities — finding new ways to invade cells, weaken the immune system and evade antibodies.

What is the omicron variant?

First identified in Botswana and South Africa in November 2021, the omicron variant surged around the world. Scientists first recognized omicron thanks to its distinctive combination of more than 50 mutations. Some of them were carried by earlier variants such as alpha and beta. Read more here.

All the most significant COVID-19 variations today are descending from omicron. After the original omicron virus evolved in the fall of 2021, its descendants split into at least five branches, known as BA.1 through BA.5. As it spread and caused an unprecedented spike in cases, it drove most other variants to extinction. Over the next few months, the subvariants took turns rising to dominance.

What is JN.1?

JN.1 is fastest-growing variant to emerge in past two years. The World Health Organization designated it a variant of interest due to its rapid growth and potential to add to the respiratory virus burden in the Northern Hemisphere. The latest booster formulation should provide good protection against it, according to the organization.

The strain emerged in August from the ultra-mutated BA.2.86, or Pirola variant. While Pirola wasn't especially remarkable, a hallmark mutation that produced JN.1 has resulted in greater transmissibility and immune evasiveness, University of Tokyo scientists reported.

What is BA.2.86?

BA.2.86 stands out in the omicron family tree because of how much it has morphed, with more than 30 mutations on its spike protein.

What is "Eris"?

The WHO designated the omicron subvariant EG.5, which includes a similar EG.5.1 strain, as one of its "variants under monitoring." Twitter users and some media outlets have nicknamed the subvariant "Eris." The virologist and researcher Stuart Turville, an associate professor at Sydney's University of New South Wales, called the EG.5 variant "a little bit more slippery" and "competitive" than its counterparts. Read more here.

What is Arcturus?

XBB.1.16, also known as Arcturus, is a subvariant of the omicron variant of COVID-19. It appears to be correlated with increased cases of conjunctivitis, the inflammation of the outer membrane of the eye better known as pink eye. Read more here.

What is the "kraken variant"?

XBB.1.5 is a descendant of the omicron XBB subvariant — which is itself a cross between two earlier strains: BA.2.75 and BA.2.10.1. Read more here.

What is "long COVID" and how many people get it?

Long COVID is the term used to describe an array of symptoms that can last for months or longer after the initial coronavirus infection. A study zeroed in on a dozen symptoms that may help define long COVID: fatigue; brain fog; dizziness; gastrointestinal symptoms; heart palpitations; sexual problems; loss of smell or taste; thirst; chronic cough; chest pain; worsening symptoms after activity and abnormal movements.

The federal definition of long COVID is symptoms that linger for four or more weeks. Cases vary in their duration, intensity and symptoms, but they often involve fatigue, headaches, dizziness and cognitive problems (or brain fog) — especially after exertion or exercise.

About 10% of people appear to suffer long COVID after an omicron infection, a lower estimate than earlier in the pandemic, according to a study published in the Journal of the American Medical Association.

Some people who experience cognitive issues after long COVID continue to struggle with brain function for at least two years, a new study shows. In the United States alone, millions of people have reported symptoms of long COVID. Research shows a majority of people experiencing long COVID symptoms have reported brain fog — a collection of symptoms, including impaired attention, concentration, memory and processing speed. Read more here.

The Defense Deptartment will buy an Edina firm's drug for radiation exposure that could also treat long COVID.

Caregivers are forming a guiding council to study and advise Minnesota on the most effective treatments for long COVID. Read more here.

Minnesota launched telephone surveys of people who tested positive for COVID-19 over the past two years to learn about any lingering effects of the disease.

People infected with the coronavirus were significantly more likely to be diagnosed with Type 2 diabetes within a year of their infection, compared with those who had not been exposed to the virus, Canadian researchers found. Read more here.

Scientists are racing to pinpoint long COVID's cause. Momentum is building around a few key theories. One is that the infection or remnants of the virus persist past the initial illness, triggering inflammation. Another is that latent viruses in the body, such as the Epstein-Barr virus that causes mononucleosis, are reactivated. A third theory is that autoimmune responses develop after acute COVID-19. Another possibility is that tiny clots play a role.

There is evidence that vaccination may reduce the chances of developing long COVID.

How can I get a quality face mask (and avoid counterfeits)?

There are so many different masks for sale, it's tough to know which ones have been tested and certified by government agencies, and which are counterfeit. Read a guide to choosing the best mask for you here.

Can I get a free N95 mask?

The Biden administration is making 400 million N95 masks available for free to U.S. residents.

How often do COVID vaccines cause heart problems in kids?

While the COVID-19 vaccines made by Pfizer-BioNTech and Moderna do seem to be associated with an increased risk of myocarditis, the latest data indicate that the absolute risk remains very small and that most cases are mild and resolve quickly. Read more here.

Do masks work?

Ordinary surgical and paper masks work when worn properly, said Chris Hogan, a University of Minnesota researcher who has studied mask effectiveness and is editor of the Journal of Aerosol Science.

Generally, the CDC says masks should "fit snugly over your mouth, nose and chin."

If you decide to keep wearing your multi-layer homemade or cloth mask, experts advise washing them every day. But proceed with caution. Read more here.

What about N95s?

Masks are best at keeping your exhaled particles away from others. Respirators, like the N95, also keep others' particles away from you. Any bona fide N95 has been certified to filter at least 95% of particles.

Many doctors and public health experts are now advocating for their use among the general public. Early in the pandemic, people were discouraged the masks over fear there wouldn't be enough for health care workers. That's no longer the case. Read more about N95 and KN95 respirators here.

How does pregnancy affect immunity?

Pregnant women who are vaccinated are nearly twice as likely to get COVID-19 as those who are not pregnant, according to a study, and have the greatest risk among a dozen medical states, including being an organ transplant recipient and having cancer.

Dr. David R. Little, a researcher at Wisconsin-based Epic, said the findings buttress CDC recommendations that additional precautions against the virus should be taken during pregnancy, such as wearing masks and maintaining safe distances. Read more here.

Should pregnant women get the vaccine?

The CDC urged all pregnant women to get the COVID-19 vaccine. Expectant women run a higher risk of severe illness and pregnancy complications from the coronavirus.

A research study based on data from Bloomington-based HealthPartners and medical centers across the country finds that pregnant women who received COVID-19 vaccines did not experience an increased risk of miscarriage.

If you're thinking of getting pregnant, there's no evidence that any vaccines, including COVID-19 vaccines, influence your chances of getting pregnant despite a myth suggesting otherwise.

Do pregnant women who get vaccinated pass the protection to their babies?

COVID-19 vaccines during pregnancy can protect babies after they're born and lead to fewer hospitalized infants, a U.S. government study suggested.

Are the vaccines safe?

A review of 6.2 million vaccine recipients in Minnesota and seven other U.S. regions found no significantly elevated rates of conditions such as stroke or heart attack immediately following COVID-19 vaccination. Bloomington-based HealthPartners participated in the study, which looked for elevated rates of 23 potential side effects in the first three weeks after people received Pfizer or Moderna COVID-19 vaccines.

What's going on with Johnson & Johnson shots?

U.S. regulators strictly limited who can receive Johnson & Johnson's COVID-19 vaccine due to the ongoing risk of rare but serious blood clots. The FDA said the shot should be given only to adults who cannot receive a different vaccine or specifically request J&J's vaccine.

Can I get a vaccine incentive?

Those programs have ended.

Who qualifies for an extra shot?

Federal officials approved an extra dose for those undergoing cancer treatment, who've received organ transplants or had other conditions that depress the body's immune system. These doses are not considered to be boosters.

Can kids get long COVID?

Yes, but studies indicate they're less likely than adults to be affected by symptoms.

Kids can develop other rare problems after a coronavirus infection, including heart inflammation or a condition known as multisystem inflammatory syndrome. Because of the potential for long-term consequences, the American Academy of Pediatrics recommends follow-up doctor visits after children recover from an initial coronavirus infection.

What is the Docket app?

Minnesota introduced the Docket app for viewing personal immunization records in response to rising demand — largely because of COVID-19 vaccination requirements by employers and organizations.

Correction: Previous versions of this story incorrectly described the Ramsey County Deputies' Federation's stance on a proposed COVID-19 vaccine mandate for county employees. Previous versions of this story incorrectly stated the Capella Building requires masks.