In February, Britain became the first country in the world to give the go-ahead for so-called "challenge trials" in humans, in which volunteers are deliberately exposed to COVID-19 to advance research into the disease caused by the coronavirus.

Experts have long worried about the emergence of drug resistance across the continent, which accounted for more than 90 percent of malaria deaths worldwide in 2019. 

Mounting evidence convinced many places to adopt mask-wearing recommendations and health authorities have for months said that crowded, badly ventilated indoor spaces are a particular risk. 

Despite recommendations from the WHO and European medicines watchdog to continue using the vaccine, "Denmark's vaccination campaign will go ahead without the AstraZeneca vaccine," Danish Health Authority director Soren Brostrom told a press conference.

Here is what we know about the two vaccines, which are based on the same technology. 

Its CoronaVac is one of four domestic vaccines given conditional approval by Chinese authorities, which helps rush emergency drugs to market.

Currently, the vaccine developed by Pfizer and its German partner BioNTech SE is approved for use in individuals aged 16 and older.

Scientists have been scrutinising a Noah's Ark of animals to find out whether -- and how -- the coronavirus was transmitted from bats to humans, with the prime suspect changing from one study to another.

The vaccines' high effectiveness has been confirmed in "real-world conditions" among health care personnel and other essential workers, who are more likely than the general population to be exposed to the novel coronavirus because of their occupations, the Centers for Disease Control and Prevention said.

The erosion between office and home boundaries during the pandemic means many white-collar workers can relate on some level to the complaints, even if the plight of elite young bankers seeking riches does not inspire sympathy.

Adults with attention deficit hyperactivity disorder (ADHD) share the challenges of living with the condition in a world that doesn’t yet understand them.

A monitoring board had "expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data," a statement from the National Institute of Allergy and Infectious Diseases said.

Leading EU countries said Thursday they would resume AstraZeneca vaccinations after the European medical regulator said the jab is "safe and effective" and not associated with a higher blood clot risk after days of commotion around the shot. 

Spain's parliament passed a law legalising euthanasia on Thursday making the country one of few to allow terminally-ill or gravely-injured patients to end their own suffering.

A year after France entered uncharted territory with its first coronavirus lockdown, a small group of volunteers has embarked on a more extreme confinement: nearly six weeks underground, with no notion of time, to study the effects of acute isolation.

Surviving Covid-19 protects most people against reinfection for at least six months, but elderly patients are more likely to be laid low by the virus a second time, researchers reported Thursday.

Hailed as a cheap, easy to store not-for-profit vaccine, the AstraZeneca shot has suffered a growing number of setbacks.

American pharmaceutical companies Gilead and Merck announced Monday they have partnered to develop a new HIV therapy that could see daily medications replaced by a treatment that can be taken at longer intervals.

Russia's Sputnik V vaccine has sown division among former Eastern Bloc countries, analysts say, with some seeing it as a godsend and others as a Kremlin propaganda tool.

Difficulty breathing, concentrating and even walking: five months after being diagnosed with Covid-19, Violaine Cousineau continues to suffer severe symptoms that prevent her from resuming normal life.

Indonesia clearly provides menstrual leave for women but in reality, each company implements this rule differently.

The Red Cross warned Wednesday of a glaring gap in the plans to roll out Covid-19 vaccines around the world, saying remote communities risked missing out.

Taro Kono told a parliamentary committee that 17 cases of anaphylaxis, a severe and potentially fatal allergic reaction, have been reported among the 107,558 health care workers who had been inoculated as of Tuesday.

Several studies show that Bispenol A (BPA) might raise the risk of health issues in toddlers and young children.

The AstraZeneca/Oxford Covid-19 vaccine appears to be more than 80 percent effective at preventing severe illness among elderly, at-risk individuals after a single dose, according to preliminary research published Wednesday.

The trial that began in August involved just over 500 people who went to emergency rooms but did not need to be hospitalized.

One in four of the world's population will suffer from hearing problems by 2050, the World Health Organization warned Tuesday, calling for extra investment in prevention and treatment.

Beverly Veres' two sons are addicted to heroin but can't get the help they need, with US health services consumed by the coronavirus pandemic at a time when overdoses are surging.

Just four percent of scientific research published on Covid-19 is relevant to Africa despite the continent containing close to a fifth of humanity, according to an analysis published Tuesday.

The Pfizer and Oxford-AstraZeneca vaccines have been "highly effective" in reducing coronavirus infections and severe illness among elderly people in Britain, with a more than 80 percent reduction in hospitalisation, official data showed Monday.