Sandwell is said to be "half way to a lockdown", with the borough among the top 10 hotspots in the UK for coronavirus after seeing up to 90 new cases a week.
Meanwhile a spike in cases in Wolverhampton over the last seven days has led to a plea from health bosses for the public to help the city avoid local restrictions.
It came as new official figures showed the re-emergence of the virus across parts of the region.
Bosses fear that further increases could leave them little choice but to impose similar restrictions to Leicester – which went back into lockdown at the end of last month after a huge rise in cases – or Blackburn, which now has targeted control measures in place.
In Sandwell 24 new cases were recorded on July 20, the highest daily figure since April 29 when 28 new cases were recorded.
And in the five days up to July 24 there were 81 new cases in the borough, the biggest five-day total since mid-May and a 10-fold increase on the last week in June. The borough has had 1,823 cases since the start of the pandemic.
Smethwick had 20 new cases last week – the joint highest in the West Midlands with Birmingham Hodge Hill, while West Bromwich and parts of Wednesbury have also been particularly badly affected.
CBS Packaging shut its factory in West Bromwich last week after 49 workers tested positive for Covid-19, while health chiefs also warned of new Covid transmissions after thousands of Albion fans flouted social distancing rules while celebrating their team's promotion to the Premier League.
Dr Lisa McNally, Sandwell's director of public health, said: "If cases continue to rise, we could be looking at a local lockdown like we have seen in Leicester or to some extent Blackburn.
"I would certainly say, looking at the statistics, we are halfway there to a lockdown.
"If we see a rise at the same rate, and it continues to go up, and we travel another 50 per cent of the journey, then we would be looking at a local lockdown."
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Dr McNally said that although Smethwick, West Bromwich and Wednesbury were the worst affected areas, any lockdown was likely to be borough-wide, and could even reach into parts of Walsall or Birmingham.
"A lockdown wouldn't follow a local authority's boundary," she added. "It could in theory be a bit of one local authority and a bit of another."
The rate of new infections per 100,000 population in Sandwell is 27.2, up from 21.7 the previous week.
Meanwhile, Wolverhampton saw 16 new cases on July 21, the highest daily figure since 18 new cases were recorded on May 15.
In the seven days up to July 27 there were an average of 12.2 cases per 100,000 residents, compared to 2.7 cases per 100,000 a week before. Health chiefs say many of the new cases are linked to family clusters or contacts of known cases.
Councillor Jasbir Jaspal, Wolverhampton Council’s cabinet member for public health, said: "If we were to let down our guard and allow the virus to begin spreading more easily, we risk not only a second wave of cases and more deaths, but also the re-imposition of lockdown measures as we have seen in places like Leicester and Blackburn in recent weeks.
“We need to do all we can to ensure that we avoid a local lockdown in Wolverhampton, and we all have a key role to play in this. It is absolutely vital that if anyone chooses to go out they must stay alert to reduce the risk of transmission.
“We also urgently need people to get tested if they have a high temperature, a new, continuous cough, or a loss or change to their sense of smell or taste."
The city has had 1,433 positive Covid tests overall, with the highest daily figure coming on April 22 when 48 new cases were recorded.
In Walsall the number of new cases has remained stable in recent weeks, with the nine new cases recorded on July 13 the joint highest figure since 12 new cases were recorded on May 20.
The rate of new cases per 100,000 population fell from 13.1 to 7.4 in the seven days to July 24.
Dudley, where 1,323 people have tested positive for the virus since March 10, has the Black Country's lowest average of just 1.1 new cases a day for the past week – a rate of 3.1 per 100,000 population.
South Staffordshire has recorded 11 new cases since June 27, while there have been 23 new cases in Stafford over the same period.
Stuart Anderson, the Conservative MP for Wolverhampton South West, said he was deeply concerned about the rise in cases in the city over the past seven days.
“People have been doing so well in treading very carefully regarding social distancing, but there are signs that this may be dropping off,” he said.
“If people move away from the guidelines we will go into another lockdown, which for the sake of public health and our economy we must to everything we can to prevent. This is not over, and my plea is for everyone to take great care in what they are doing.”
West Bromwich East MP Nicola Richards, said: "I want to remind everyone in West Bromwich and across Sandwell that this awful disease is still around and that all precautions should be followed as per the guidance from Public Health England.
"It is vital that everyone one of us maintains measures such as social distancing, wearing masks in shops, on public transport, in takeaway restaurants and the washing of hands regularly.
"If you have any symptoms then please ensure that you are tested and self-isolate for the recommended period of time.
"We do not want a localised lockdown in Sandwell and I urge everyone to continue to follow the guidance and stay alert."