Smallpox vaccines being administered in Paris in 1941. When the disease was eradicated and vaccination came to a stop, that created an opening for its virus relative monkeypox. Roger Viollet via Getty Images hide caption

Michaeleen Doucleff
Spallanzani infectious disease hospital Director Francesco Vaia talks to reporters at the end of a news conference Friday in Rome. Andrew Medichini/AP hide caption
Symptoms of the monkeypox virus are shown on a patient's hand, from a 2003 case in the United States. In most instances, the disease causes fever and painful, pus-filled blisters. New cases in the United Kingdom, Spain and Portugal are spreading possibly through sexual contact, which had not previously been linked to monkeypox transmission. CDC/Getty Images hide caption
Rare monkeypox outbreak in U.K., Europe and U.S.: What is it and should we worry?
Dr. Jesse Clark is an infectious disease specialist at the University of California, Los Angeles. The COVID pandemic "has spurred people to try to end the HIV epidemic again," he says. Grace Widyatmadja/NPR hide caption
One of the first clinical trials of a new mRNA vaccine for HIV is underway
A woman wears a face shield to protect against COVID-19 at a taxi stand in Soweto, South Africa, where an omicron variant is causing a COVID-19 surge. Denis Farrell/AP hide caption
If you've had omicron before, are you safe from infection by the new variants?
A case of COVID-19 brought 12-year-old Harry Nelson to the emergency room in Syracuse, N.Y., where cases are surging, His mother, photographer Paula Nelson, says he first had mild symptoms — just a headache — but later ran a high fever and began vomiting, which meant he couldn't keep down fever-relief meds. At the ER, he needed saline to rehydrate, Tylenol for his fever and meds to stop vomiting. Paula Nelson for NPR hide caption
Rosy, 6, gives COVID tests and vaccines to her stuffed animals. She herself has been exposed to SARS-CoV-2, the coronavirus that causes COVID-19, multiple times and never tested positive. What's her secret? Michaeleen Doucleff/NPR hide caption
Why hasn't my daughter caught COVID? 2 factors likely protect her — and maybe you too
Delta and omicron met up inside 1 person and made the Frankenstein hybrid 'deltacron'
A new type of coronavirus variant is a mixture of omicron and delta strains
Security guards stand in front of the Huanan Seafood Wholesale Market in Wuhan, China, on Jan. 11, 2020, after the market had been closed following an outbreak of COVID-19 there. Two new studies document samples of SARS-CoV-2 from stalls where live animals were sold. Noel Celis/AFP via Getty Images hide caption
Striking new evidence points to Wuhan seafood market as the pandemic's origin point
Physical evidence indicates that the coronavirus emerged at Wuhan seafood market
Staff volunteers queue to receive a fourth dose of the Pfizer COVID-19 vaccine at Sheba Medical Center in Israel on Dec. 27, 2021, as the hospital conducted a trial of a fourth jab of the vaccine. Jack Guez/AFP via Getty Images hide caption