COVID-19: What you need to know about the coronavirus pandemic on 23 July

Confirmed cases of COVID-19 have passed 192.5 million globally, according to Johns Hopkins University. The number of confirmed deaths stands at more than 4.13 million. More than 3.76 billion vaccination doses have been administered globally, according to Our World in Data.

Advisors to the US Centers for Disease Control and Prevention are considering evidence suggesting that a booster dose of COVID-19 vaccines could increase protection among people with compromised immune systems.

The Biden Administration has released $3 billion in COVID-19 funds to help local communities boost their economies in the wake of the pandemic.

The Philippines has announced plans to ban travel from Malaysia and Thailand and tighten restrictions in the Manila area to prevent the spread of the Delta variant.

India has reported 35,342 new COVID-19 cases, taking its tally to more than 31.2 million confirmed cases.

China's eastern province of Jiangsu reported 12 new domestically transmitted COVID-19 cases yesterday – taking its total to 23 since 20 July. It's the first local outbreak since the pandemic began last year.

Prime Minister Pedro Sanchez has announced that Spain will begin to donate 7.5 million COVID-19 vaccine doses this week. The vaccines will be distributed through COVAX, the vaccine-sharing facility.

Mexico has reported its highest daily jump in infections since January, with 16,244 new confirmed COVID-19 cases – although the government has said the real number of cases is likely significantly higher.

Vietnam could soon approve a domestically produced COVID-19 vaccine for emergency use, the government said in a statement yesterday.

Australia's New South Wales state has reported its biggest daily rise in new COVID-19 cases so far this year, prompting a tightening of restrictions in capital Sydney.

State officials have labelled the situation a 'national emergency', with state Premier Gladys Berejiklian saying it was likely restrictions would be extended beyond the current 30 July end date.

"There is no doubt that the numbers are not going in the direction we were hoping they would at this stage," Berejiklian said as she announced 136 new cases in New South Wales.

The Trans-Tasman bubble, which allowed quarantine-free travel between New Zealand and Australia, has also been suspended for at least eight weeks.

A British study has found that a longer gap between doses of the Pfizer COVID-19 vaccine leads to higher overall antibody levels than a shorter gap. However, the study found a sharp drop in antibody levels after the first dose.

The study might help inform vaccination strategies against the Delta variant, which reduces the effectiveness of a first dose of COVID-19 vaccine even though two doses are still protective.

"For the longer dosing interval ... neutralising antibody levels against the Delta variant were poorly induced after a single dose, and not maintained during the interval before the second dose," said the authors of the study, which is being led by the University of Oxford.

"Following two vaccine doses, neutralising antibody levels were twice as high after the longer dosing interval compared with the shorter dosing interval."

"I think the 8-week [gap] is about the sweet spot," Susanna Dunachie, joint chief investigator on the study, told reporters.