Collaborating with devoted colleagues, Dr. Kariko laid the groundwork for the mRNA vaccines turning the tide of the pandemic.

A molecular biologist, she helped establish the virus as the cause of AIDS, then cloned it and took it apart to understand how it evades the immune system.

The agency also explained more directly that people without symptoms may spread the virus. The acknowledgments should have come sooner, some experts said.

A cash reward works best with Democrats, and relaxing safety guidelines seems to motivate Republicans, a survey study shows.

An unusual transplant may revive tissues thought to be hopelessly damaged, including the heart and brain.

An analysis covering 66 million young people has found plummeting rates of precancerous lesions and genital warts after vaccination against the human papillomavirus.

A third of parents now feel they should be the ones to decide whether to get their children immunized against measles, mumps and other childhood diseases.

Researchers in Britain found that people who go to museums, the theater and the opera were less likely to die in the study period than those who didn’t.

Congress long ago allowed people with end-stage kidney failure to receive Medicare. Why not do the same for people with other chronic illnesses?

Tuberculosis kills 1.5 million people each year. Lockdowns and supply-chain disruptions threaten progress against the disease as well as H.I.V. and malaria.

An analysis covering 66 million young people has found plummeting rates of precancerous lesions and genital warts after vaccination against the human papillomavirus.

Portugal is among the most highly vaccinated countries in the world. Vice Adm. Henrique Gouveia e Melo, who led the campaign, said there was a key to his success: Keep politics out of it.

This fall, Americans will be urged to get shots against the flu, Covid and, if they’re older, R.S.V.

“Sometimes very big problems, they have very simple solutions.”

It’s the biggest health crisis you’ve never heard of. Doctors, philanthropists and companies are trying to solve it.

Baby Boy Royer, who underwent an operation for spina bifida as a fetus, had the biggest defect that the surgical team had attempted to repair.

The billionaire is working with the W.H.O., drugmakers and nonprofits to defeat the coronavirus everywhere, including in the world’s poorest nations. Can they do it?

A surge of severe lung ailments has baffled doctors and public health experts.

Francis Collins pledged to decline to speak at conferences that do not include enough women in prominent speaking roles.

Doctor groups are recommending testing and isolation for people who lose their ability to smell and taste, even if they have no other symptoms.

Congress long ago allowed people with end-stage kidney failure to receive Medicare. Why not do the same for people with other chronic illnesses?

The agency also explained more directly that people without symptoms may spread the virus. The acknowledgments should have come sooner, some experts said.

Wearing a face mask takes some getting used to. To get the most benefit, you need to avoid these common mistakes.

Dermatologists who specialize in hair loss say that the key ingredient in a topical treatment worked even better when taken orally at a low dose.

Humility is not the boldest of personality traits, but it’s an important one, studies find. And it’s hard to fake.

Inconsistent protocols, limited resources and a patchwork of decision making have led to an undercounting of people with the coronavirus who have died, health experts say.

A banana might reasonably replace sports drinks for those of us who rely on carbohydrates to fuel exercise and speed recovery.

Twitter accounts that were used to meddle in the 2016 presidential election also sent both pro- and anti-vaccine messages and insulted parents.

Valerie Louie rescued dogs and matched them with families, including ours. These beloved pets helped countless people bear up during the pandemic, making her death a particular Covid-19 cruelty.

Researchers identified nearly 400 common medical practices and theories that were contradicted by rigorous studies. Here are some of the most notable findings.

Well before rationing caused by coronavirus, protocols were established about “who lives and who dies.”

A molecular biologist, she helped establish the virus as the cause of AIDS, then cloned it and took it apart to understand how it evades the immune system.

They are our apex predator, the deadliest hunters of human beings on the planet.

Headlines suggest that the epigenetic marks of trauma can be passed from one generation to the next. But the evidence, at least in humans, is circumstantial at best.

A new study looks at what might have been a dangerous outbreak — had it not been for vigilant mask wearing.

Postpartum hemorrhage, which kills 100,000 women in developing countries, can be treated with a nearly forgotten blood-clotter invented in the 1950s.

His research expanded the pool of donors whose bone marrow was less likely to be rejected by patients with leukemia and other blood disorders.

The authorization of a third Covid-19 vaccine will bring millions more doses within days. But health officials worry that some people will see the vaccine as the inferior choice.

A look at how opioids hijack the brain, from temptation and tolerance to relapse and recovery.

Doctors grew sheets of healthy skin that were transplanted onto a boy with a genetic disease that caused blistering and tearing all over his body.

A hand-held device brings medical imaging to remote communities, often for the first time.

Editors at the world’s leading medical journal said the Trump administration “took a crisis and turned it into a tragedy.”

Lean people were especially responsive to exercise’s effects on the bacterial makeup of our guts.

Four people died on the Zandaam cruise ship after it was turned away in Chile. The United States is easing protocols to help speed cruise passengers home. But can that be done safely?

It’s not just the lungs — the pathogen may enter brain cells, causing symptoms like delirium and confusion, scientists reported.

Only a small minority of people panic under threat, research shows. Far more don’t take the threat seriously enough.

Sexual-minority teenagers are at far greater risk for depression, bullying and many types of violence than their straight peers, the C.D.C. has found.

Infants under 1 year old should not be exposed to electronic screens, and children between the ages of 2 and 4 should not have more than one daily hour of “sedentary screen time,” the agency said...

Sociologists are just beginning to understand who is buying guns and how gun ownership makes them feel.

The candidates discussed lots of topics at the second Republican debate, but there was one they would have done better to leave alone.

The Food and Drug Administration has approved the use of Gardasil 9, a vaccine against nine strains of the human papillomavirus for older age groups.

“Sometimes very big problems, they have very simple solutions.”

The C.D.C. said Thursday that vaccinated Americans no longer needed masks in most places. Other disease experts recently had a different message: that masks were necessary in public.

The hospitalized patients showed signs of deteriorating neurological function, ranging from confusion to coma-like unresponsiveness, new research indicates.

The surgical masks used in risky settings like hospitals offer much less protection against the coronavirus, an analysis found.

The agency also explained more directly that people without symptoms may spread the virus. The acknowledgments should have come sooner, some experts said.

The virus injects a tiny but remarkably complex strand of RNA into infected cells.

From April 10 to May 10, a dozen Felician sisters at the Presentation of the Blessed Virgin Mary convent died of Covid-19. In June, a 13th sister died after contracting the coronavirus.

Her work with Dorothy Hodgkin unleashed a bonanza of lifesaving antibiotics and gave other female scientists a foothold in a male-dominated field.

A computer model of the cruise-ship outbreak found that the virus spread most readily in microscopic droplets light enough to linger in the air.

For every known case of coronavirus, another five to 10 cases are out there undetected, a new study suggests.

“When hospitals are understaffed, people die,” one expert warned as the U.S. health systems reach a breaking point in the face of the Delta variant.

The coronavirus outbreak has magnified all kinds of fears. Try living in the moment. Take stock of what’s working. Turn off the television.

Researchers say there has been a substantial increase in women under the age of 26 who have received a diagnosis of early-stage cervical cancer since the health law came into effect in 2010.

Juli Mazi of Napa, Calif., also sold “immunization pellets” to patients, federal prosecutors said.

Airborne virus plays a significant role in community transmission, many experts believe. A new study fills in the missing piece: Floating virus can infect cells.