Use of Pfizer Inc.’s COVID-19 oral antiviral treatment Paxlovid jumped 315 percent over the past four weeks, the U.S. Department of Health and Human Services said on May 17, as health officials try to address unexpectedly light demand.

A chain of events possibly triggered by unrecognized infection with the SARS-CoV-2 coronavirus could be causing the mysterious cases of severe hepatitis reported in hundreds of young children around the world, researchers suggest.

Half of the COVID-19 patients discharged from a Chinese hospital in early 2020 still have at least one symptom two years later, a new study shows. Additionally, new findings suggest patterns of inflammatory proteins in the blood of people with long COVID may someday help guide individualized treatment.

Patients diagnosed with cancer more than a year before contracting COVID-19 and those not receiving active treatment may be no more vulnerable to worse COVID outcomes than those without cancer, according to a new study. Additionally, researchers warned that passengers are still at risk of coronavirus infection while traveling on airplanes and also in airports.

Severe obesity may weaken the effectiveness of COVID-19 vaccines in those who have never been infected with the coronavirus, according to a small Turkish study. Additionally, South African researchers have found infection with the Omicron variant of the coronavirus can significantly improve the immune system’s ability to protect against other variants, but only in people who have been vaccinated.

The Omicron variant of the SARS-CoV-2 virus is intrinsically as severe as previous variants, unlike assumptions made in previous studies that it was more transmissible but less severe, a large study in the United States found.

COVID-19 cases in the Americas increased by 12.7 percent last week from the prior week, the Pan American Health Organization (PAHO) said on May 4, as infections continued to rise in Central and North America.

Following the record surge in COVID-19 cases during the Omicron-driven wave, some 58 percent of the U.S. population overall and more than 75 percent of younger children have been infected with the coronavirus since the start of the pandemic, according to a U.S. nationwide blood survey released on April 26.

U.S. President Joe Biden’s administration is aiming to expand access to COVID-19 oral antiviral treatments like Pfizer Inc.’s Paxlovid by doubling the number of locations at which they are available, the White House said on April 26.

The U.S. Food and Drug Administration approved Gilead Sciences’ antiviral therapy Veklury (remdesivir) as the first treatment for COVID-19 in young children.