As the Melbourne COVID outbreak continues to escalate, the government will impose a harsh lockdown for the fourth time.

The lockdown will apply for all of Victoria, with metropolitan Melbourne and regional Victoria to be treated equally.

For now, it expires at 11.59pm on Thursday, June 3.

The latest update from the DHHS said there outbreak had had blown out to 25 cases, with 12 acquired in the last 24 hours.

There are now 79 sites listed on the exposure list.

See the full list of exposure sites here.

There will be only five reasons to leave home and you must stay within five kilometres of your home:

Masks must be worn indoors and outdoors.

Schools and universities will move to remote learning.

No visitors are allowed to your home other than intimate partner. Single household bubbles are permitted, if you live alone you can make a bubble with another person.

No public gatherings are allowed.

Restaurants, pubs and cafes can provide takeaway only.

The construction industry will continue.

Only essential retail can remain open - other retail can provide click and collect.

Childcare and kindergartens are to remain open as per the last lockdown.

Approved professional sport will continue but without crowds.

Aged care facilities will be allowed no visitors except for very limited reasons.

In hospitals, visitors are only allowed for end of life, accompanying a birth, or caring for a child.

Funerals will allow a maximum of 10 people.

Community sport, accommodation, pubs, hotels, casinos, indoor and outdoor entertainment, swimming pools, community libraries/toy libraries, hairdressing, drive in cinemas amusement parks, galleries and museums will all close.

From tomorrow morning, vaccinations at state sites will be expanded to include people aged 40-49 for the Pfizer vaccine.

If you are over 40, you are now eligible for a vaccination.

On the advice of our public health team, Victoria will move to circuit breaker restrictions from 11:59pm tonight.

These settings will remain in place until 11:59pm on 3 June - but if we can end that sooner, we will.

As we've seen here, and across Australia, this kind of short, sharp action is effective in stopping this thing in its tracks.

Our public health experts' prime concern: just how fast the B1.617.1 variant is moving.

Overseas, they haven't been able to track how quickly this version of the virus can move. Here in Victoria, though, we're seeing not only how quick it is - but how contagious it is too.

Our contract tracers are identifying and locking down first ring, second ring and third ring contacts within 24 hours. That's faster than ever. And yet this variant is still moving faster.

The time between catching the virus and passing it on is tighter than ever. The 'serial interval' - how long it takes between the onset of symptoms in the first and secondary case - is in many cases just over a day.

And in just 24 hours, the number of cases has doubled.

It means that although these cases are all connected, this variant of the virus is making people more infectious, more quickly.

We've seen other countries come up against these variants and lose. Badly. Places like Taiwan that have gone from no or very low cases to skyrocketing numbers in the space of just days and weeks - and now are struggling to get it under control.

We also know our nation's vaccine rollout has been slower than we'd hoped. And if more people were vaccinated, we might be facing a different set of circumstances. Sadly, were not.

If we make the wrong choice now, if we wait too long, if we hesitate too much, this thing will get away from us.

And lives will be at risk.

It's why from 11:59pm tonight, there will be five reasons to leave home:

Food and supplies. Authorised work. Care and caregiving. Exercise, for up to two hours and with one other person. And getting vaccinated.

Exercise and shopping will be limited to five kilometres from home. If there's no shops in your 5km radius, you can travel to the ones closest to you.

Shopping is also limited to one person per day, per household.

Face masks will also need to be worn inside and outdoors - everywhere except your own home.

Private and public gatherings will not be permitted, although visiting your intimate partner continues to be okay.

Single person bubbles will also be allowed.

Childcare and kinder will remain open, but schools will need to close other than for the children of authorised workers and vulnerable kids.

Shops like supermarkets, food stores, bottle shops, banks, petrol stations and pharmacies will also remain open.

Cafes and restaurants will be able to offer take-away only. Gyms, hairdressers, community facilities and entertainment venues will all close. Non-essential retail may only open for click and collect.

Hotels and accommodation can only stay open to support guests already staying onsite. No new bookings can be made - unless it's for one a permitted purpose, like authorised work.

Advice on who can open, and who can't, will be made available online ahead of directions coming into place - as will the full list of authorised workers and workplaces.

It's clear - more than ever - this virus isn't going away. And vaccines are the only way we'll ever get back to normal.

Without full vaccination, this virus will just keep mutating - and just keep making its way back in.

To that end, from tomorrow and dependent upon supply from the Federal Government, all Victorians over the age of 40 will be eligible for the COVID-19 vaccine.

My message to those Victorians: if you're eligible, get vaccinated. Make your plan today.

If someone you love is eligible, make a plan together.

Do it for yourself. Your family. Your friends. Your community. Whatever your motivation - please do it.

Because vaccination is our only real ticket out of this pandemic.

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