The Loop: Another Pfizer booster on table in US, hospital hostages in beseiged Mariupol, and a Grammys showstopper

Good morning, it's Wednesday, March 16. Here's what you need to get going today.

One thing to know right now: Pfizer is expected to ask for a *second* booster

Here's the lowdown: 

• US regulators are expected to get the request this week for the extra shot — but only for those over 65, a source has told AP
• It would add a fourth dose to the regimen, which currently consists of a primary series of two shots, followed months later by a booster dose, in an effort to provide maximum protection to the over-65 population that has been hit hardest by the pandemic
• The submission to the US Food and Drug Administration is expected to include data collected in Israel, where a second booster is authorised for many people over age 18
• The company has yet to respond, but its CEO Albert Bourla recently told the Washington Post that data suggests a fourth dose dramatically improves protection against the dominant Omicron variant of the virus compared to the third dose after three-to-six months
• Here's Harvard vaccine researcher Dan Barouch:

One thing you’ll be hearing about today: Hospital hostages, fines for a reporter — the latest on Ukraine 

Here's what happened overnight:

• Russian forces are reportedly holding patients and staff captive at a hospital in the besieged city of Mariupol in southern Ukraine
• The city's Deputy Mayor, Sergei Orlov has told the BBC about 400 people at the regional intensive care hospital have been taken hostage. He says it's the same hospital that was demolished by a Russian strike last week

Russian shelling leaves apartment buildings heavily damaged and destroys a shopping mall in western Mariupol. (AP: Maxar Technologies)

• The Russian news producer who interrupted a live state broadcast with anti-war messages has been fined. Marina Ovsyannikova an employee of Russia's state-run Channel One, walked into the studio during Monday's evening news show with a poster saying "no war" and "Russians against the war." She was held in police custody and on Tuesday was ordered to pay a fine of 30,000 rubles (about $375)

The protest was shown live on Russian government broadcaster TV Channel One.

• A veteran war journalist has been killed just outside Kyiv. Pierre Zakrzewski was travelling in a vehicle with journalist Benjamin Hall,  when it came under heavy fire. The 55-year-old has died, while Mr Hall is currently in hospital being treated for injuries. In a memo to staff, chief executive of Fox News Suzanne Scott has celebrated Mr Zakrzewski's decorated career covering conflicts in Iraq, Afghanistan and Syria, calling it a "heartbreaking day"

• NATO Secretary-General, Jens Stoltenberg, says the treaty alliance is aware Russia is trying to 'stage the pretext' for using chemical weapons in its military assaults on Ukraine. Russia has claimed western powers are developing biological and chemical weapons in Ukraine

News while you snoozed

Let's get you up to speed.

• A man has died in floodwaters overnight near Broken Hill.  Emergency services were called to Menindee Road, 35km east of Broken Hill, after reports a man had driven into floodwaters. Police say the 56-year-old man died after he exited his four-wheel drive and was sucked into a concrete pipe due to the force of the waters
• Police say more bodies could be found in the burnt-out ruins of a Sydney boarding house where at least three people were killed yesterday. A witness told officers she saw a man running from the Newtown building just before the explosion and fire
• Another 40 motorhomes are headed for flood-ravaged Lismore. They're coming from Brisbane and will be driven by Queensland Rural Fire Service volunteers
• And overseas, no charges will be filed against the Chicago police officers who fatally shot 13-year-old Adam Toledo and 22-year-old Anthony Alvarez during foot pursuits within days of each other last year, a prosecutor has announced

The news Australia is searching for

• Queen Elizabeth: Despite missing the major Commonwealth Day service yesterday, the Queen was taking video meetings the next day — and even having someone around for tea:

• Carrie Bickmore: One of the hosts of Network 10's The Project announced last night that she's taking a few months off to move to the UK with her family for a while. There hasn't been confirmation yet on who will step in

One more thing: Trifecta coming up for Grammys

The Grammy Awards are bringing three of the world's biggest pop acts — Olivia Rodrigo, BTS and Billie Eilish — to perform during next month's ceremony in Las Vegas.

Also up: Brandi Carlile, Brothers Osborne and Lil Nas X with Jack Harlow.

But the leading nominee is the multitalented Jon Batiste with 11 nods in a variety of genres including R&B, jazz, American roots music, classical and music video.

Justin Bieber, Doja Cat and H.E.R. are tied for the second-most nominations with eight apiece.

That's it for now

We'll be back later on with more.

ABC/wires