Almost 3,000 cases of the Indian variant have been identified in the UK — up from 2,300 on Monday.
Clusters have been found across the capital and Hounslow will be subject to increased surge testing and a speedier vaccinations programme.
Hounslow’s director of public health Kelly O’Neill said: “More than 130,000 Hounslow residents (approximately 48 percent of the total population) have been vaccinated since December, but we cannot be complacent, and we know there is still a large number of eligible adults in the borough who have yet to be vaccinated.
“If we are to prevent further infection rate rises, we need all residents to become part of the solution and get vaccinated.”
Surge testing has also been introduced in Hackney and Tower Hamlets after a “small number” of positive cases of the strain. In Barking and Dagenham a secondary school pupil is one of at least 10 people to have tested positive for the Indian variant.
Teams were going door-to-door in Mile End in an attempt to isolate cases, while Hackney has set up five testing sites in Dalston and Shoreditch where both the Indian and South African variants have been found.
However, while more than 8,000 test kits have been ordered or collected by people living in the areas, just 20 percent have been returned to collection sites, the council said.
Dr Sandra Husbands, director of public health for Hackney, urged all residents to get tested and return the kits “as soon as possible over the next 24 hours”.
Judith Mintosha, 40, brought her son Denzel, nine, to a hub in Dalston.
She said: “It is very worrying. My neighbour died of Covid recently and the area was really badly affected. The idea that people won’t take it seriously and it will happen again is very scary.”
She said she was worried about children at school not wearing masks and not socially distancing. “You don’t know how these variants are going to impact them,” she said.
East London boroughs are being particularly cautious after the Kent variant swept through at Christmas causing some areas to record the highest case rates in the country.
There are still many who remain suspicious about the vaccine. Hackney has one of the poorest take-up rates for over-forties in the country at 79 per cent.
The borough, along with neighbouring Newham and Tower Hamlets, also has a younger population than other parts of the capital, so far fewer people have had the jab.
Ms Mintosha said she has not yet received her Covid vaccine after confusion about how she would be called up.
She said: “I thought my GP would get in contact but that didn’t happen. I didn’t realise you could go to a vaccination centre or book online as soon as you were eligible. I think that needs to be made clearer to people.”
Mental health worker Adrian Dimmick, 65, gets tested three times a week for Covid, despite receiving both jabs.
He said: “We’ve seen so many different variants I don’t think it really registers with people and they aren’t that worried. I believe in just sticking to the rules until this is over. We should have closed airports earlier. But what is really worrying is I know people who still don’t believe Covid exists. It’s just hard to engage with them now.”
Tower Hamlets mayor John Biggs said vaccine rates were improving in the area but the younger population made variants particularly dangerous.
He said: “The pandemic has taught us that we need to really be on our guard about these variants. In theory, a place like Tower Hamlets and east London is a fantastic incubator for the virus because of its population density.
“It may also spread more rapidly, given we have a very young population and many have not been vaccinated. Vaccine hesitancy is much better than it was, but we can always do better still. The figures are stubborn among some communities. We are also battling Covid fatigue, people want to get on with their lives. We have to get that ‘be careful’ message across because there is still a very real danger.”