Victoria’s vaccine hotline was flooded with inquiries on Thursday after the state widened eligibility for doses at the same time it announced a seven-day lockdown would begin at midnight.

The hotline promptly crashed under a wave of demand from Victorians, leaving those eager to get a coronavirus shot struggling to work out how they could.

State health authorities made their strongest push yet for all eligible residents – which now means anyone in Victoria aged over 40 – to go out and get the shot as soon as possible.

Those aged from 40 to 49 must schedule an appointment via the vaccine hotline to receive the Pfizer vaccine. Walk-ins are allowed at mass vaccine hubs for those who will take the AstraZeneca shot.

Tweet from @VicGovDH

Victorian Health Minister Martin Foley said the number of operators would be increased.

“We would encourage you to either phone or walk up if you are over 50 for the AstraZeneca,” Mr Foley said.

Thursday’s developments came with Victoria set to enter its fourth coronavirus lockdown, amid rising concerns about a cluster spreading across the city.

It grew to 26 cases on Thursday, with more than 150 exposure sites across Melbourne and in country Victoria.

Among those who have caught the virus is a person in their 70s who is in intensive care and described as “not in a good way”.

Acting Premier James Merlino confirmed the lockdown would begin at 11.59pm on Thursday.

People will be able to leave home only for five reasons – to shop for food and essential items, provide or receive care, exercise, work or study if they are unable to from home, and to get vaccinated.

A five-kilometre travel limit will also be imposed for exercise and shopping, as will compulsory use of masks indoors and out.

All non-essential retail will close but essential retailers such as supermarkets, bottle shops and pharmacies will remain open.

Shopping will be limited to one person per day per household.

Cafes and restaurants can offer only takeaway.

Child care and kinder will stay open but schools will close, except for a small cohort of students.

The lockdown is scheduled to last until 11.59pm on June 3, though Mr Merlino said it could end earlier.

He said he had faith in the state’s contact tracing team but the virus was “running faster than we have ever recorded”.

States, territories slam borders shut

NSW Premier Gladys Berejiklian has so far resisted closing her state’s border to Victorians.

But anyone arriving in NSW who has been in Victoria since 4pm on Thursday must adhere to follow the state’s lockdown rules.

Ms Berejiklian urged Victorians not to consider fleeing north to escape another COVID-19 lockdown.

“There are 55 crossings of the border and we just ask everybody to do the right thing,” she told Nine’s Today on Thursday.

• Passengers removed from Ghan after Vic outbreak

Authorities are already worried the virus may have spread into NSW, after several teams from a NSW sporting club visited an exposure site in northern Victoria.

The Northern Territory has declared greater Melbourne and Bendigo hotspots from 12.01am on Thursday and moved 100 travellers from Victoria into supervised quarantine.

Western Australia instituted a “hard border” with Victoria from 10am (WA time) on Thursday.

Queensland has declared all of Victoria a hotspot, with any arrivals from the state to be sent to hotel quarantine.

Non-residents travelling from Victoria will not be able to enter the ACT without an approved exemption prior to arrival. Those allowed in will be required to follow stay-at-home orders.

Tasmania has declared Victoria “high risk” and closed its border to the entire state from 2pm (AEST). Only essential travellers are allowed in.

SA has closed its border to Greater Melbourne, except for essential travellers who must complete 14 days of self-quarantine on arrival.

Tweet from @AnnastaciaMP

Chief health officer fires up on Twitter

Victoria’s chief health officer Professor Brett Sutton issued two frustrated tweets on Thursday afternoon in defence of contact tracing teams.

“I think I’ve been pretty calm over the last 16 months,” Professor Sutton wrote.

“But I *will* get fired up when contact tracers are attacked. They do extraordinary work and do it brilliantly. 10,000 contacts found! The false narrative hurts real people, mentally.”

Tweet from @VictorianCHO

Earlier on Thursday, Mr Merlino said the “circuit breaker” lockdown was necessary because of the concerning speed of the virus’ spread.

Already more than 10,000 primary and secondary contacts have been identified, with Professor Sutton saying more infections should be expected.

• See an updated list of exposure sites here

‘Panic-buying: Don’t do it’

Along with the now-familiar lockdown rules, panic-buying has also returned to Victoria.

But based on reports from social media, not everyone was convinced.

Tweet from @laurel_irving

Tweet from @Melbchief

Victoria’s lockdown rules

From midnight until at least midnight on June 3, Victorians can leave home only to shop for food and essential items, provide or receive care, exercise, work or study if unable to do so from home, and get vaccinated.

The five-kilometre travel limit will also be reimposed for exercise and shopping, as will mandatory masks whenever leaving home.

All non-essential retail will close but supermarkets, bottle shops and pharmacies will remain open.

Cafes and restaurants can offer only takeaway.

Child care and kinder will stay open, but schools will close.

Professional sports events such as the weekend’s AFL games in Melbourne will continue, but without crowds.

Late on Thursday, AFL boss Gillon McLachlan described the developments as disappointing.

“But the events of the last 24, 48 hours reiterate the reasons why we have put in place the contact tracing requirements at matches – to keep the community as safe as possible as we continue to navigate through the pandemic,” he said.

“Our thoughts are with all Victorians and what we know is a difficult period for many in the community.”

-with agencies