COVID-19: What you need to know about the coronavirus pandemic on 28 January

Confirmed cases of COVID-19 have passed 366.5 million globally, according to Johns Hopkins University. The number of confirmed deaths has now passed 5.63 million. More than 10 billion vaccination doses have been administered globally, according to Our World in Data.

Russia's daily COVID-19 cases surged to 98,040 on Friday, a new record high for the eighth consecutive day as the Omicron variant continued to spread, the government's coronavirus task force said. The number of new infections was a significant jump from the 88,816 reported on Thursday. Officials also said that 673 people had died in the past 24 hours.

Australia suffered its deadliest day of the COVID-19 pandemic on Friday with nearly 100 deaths, but several large states said they expect hospital admissions to fall amid hopes that the latest wave of infections would begin to subside.

Hong Kong will cut quarantine for arriving travellers to 14 days from 21 starting 5 February, leader Carrie Lam said on Thursday. The decision follows intense lobbying from finance executives and diplomats who said the measure was hurting competitiveness.

The European Union's drug regulator has given the green light to Pfizer's antiviral COVID-19 pill for treating adults at risk of severe illness, as the region scrambles to boost its arsenal to fight the Omicron variant.

Finland will begin gradually easing COVID-19 restrictions from 1 February instead of mid-February as initially planned, the government said late on Thursday. "The burden on intensive care units has taken a turn in a better direction," Finland's Minister for Health and Social Affairs, Hanna Sarkkinen, told reporters.

Morocco will reopen its airspace for international flights starting 7 February, the state news agency reported on Thursday. Morocco banned all inbound international passenger flights in November due to concerns over the Omicron COVID-19 variant.

COVID-19 boosters increase protection against death from the Omicron variant to 95% in people aged 50 or over, the UK Health Security Agency (UKHSA) said on Thursday.

The UKHSA said that around six months after a second dose of any of the COVID-19 vaccines, protection against death with Omicron was around 60% in those aged 50 and over. However, this increased to around 95% two weeks after receiving a booster vaccine dose.

UKHSA added that data continued to show high levels of protection against hospitalization from the booster. Effectiveness against hospitalization was around 90% for the Pfizer-BioNTech shot, dropping to 75% 10-14 weeks after the booster.

For Moderna, effectiveness against hospitalization was 90-95% up to nine weeks after the booster.

"The evidence is clear – the vaccine helps to protect us all against the effects of COVID-19 and the booster is offering high levels of protection from hospitalization and death in the most vulnerable members of our society," said Dr Mary Ramsay, Head of Immunization at UKHSA.

The world's first medical trial authorized to deliberately expose participants to the coronavirus is seeking more volunteers as it steps up efforts to help develop better vaccines.

The Oxford University trial was launched last April, three months after Britain became the first country to approve what are known as challenge trials for humans involving COVID-19.

Its first phase, still ongoing, has focused on finding out how much of the virus is needed to trigger an infection while the second will aim to determine the immune response needed to ward one off, the university said in a statement.

Researchers are close to establishing the weakest possible virus infection that assures about half of people exposed to it get asymptomatic or mild COVID-19.

They then plan to expose volunteers - all previously naturally infected or vaccinated - to that dose of the virus's original variant to determine what levels of antibodies or immune T-cells are required to prevent an infection.

"This is the immune response we then need to induce with a new vaccine," said Helen McShane, Oxford University Professor of Vaccinology and the study's chief investigator.

The trial's findings will help make future vaccine development much quicker and more efficient, the statement said.

Global immunologists have been seeking to pinpoint the immune reaction that a vaccine must produce to shield against the illness, known as a correlate of protection. Once discovered, the need for mass vaccine trials is greatly reduced.