The prime minister will hold the televised briefing at 5pm on Friday, alongside chief medical officer Chris Whitty and chief scientific officer Patrick Vallance.
It amid speculation over whether new lockdown rules could be introduced.
He is likely to face questions on how long the current lockdown could last, after telling reporters on Thursday it was “too early” to say whether it would still be in place by summer.
Reports on Thursday suggested ministers were considering giving those who tested positive for the virus £500 in a bid to encourage more people to self-isolate.
It comes amid government polling that says just 17% of people with symptoms were coming forward for a test.
Dr Mike Tildesley, a member of Sage subgroup the Scientific Pandemic Influenza Group on Modelling (Spi-M), said there were “early signs” cases were dropping.
He told Times Radio: “One of the key things actually that we need to think about is not necessarily just ramping up the rules if things don’t seem to be working but actually looking at making the rules better that we have in place, and one of the key problems actually is people isolating.
“Some kind of support for people so they can see through their isolation is actually pretty important, so that we really do get on top of these numbers.”
He said it was “pretty unclear how we can tighten restrictions further” but he said there were signs the “lockdown is possibly working in terms of taking the R number below 1”.
Imperial College London’s React study on Tuesday, however, suggested that R was still above 1 across the country, which would mean the pandemic was still growing.
Only 18% of people with symptoms are self-isolating for the full 10 days as instructed, professor Susan Michie, of the Scientific Pandemic Insights Group on Behaviours, which advises the government, said.
She told BBC Radio 4’s Today programme the £500 may not be enough.
“There will be people, for example single earners in a household looking after a family where £500 over 10 days, £50 a day, is not enough to pay the rent, to pay all the bills and put food on the table,” she said.
“There is a particular group of people who would need more from that £500 but at least the government is recognising this is a key weakness in the whole pandemic strategy.
“If you have 82% of people with symptoms wandering around the community it is very very difficult to bring this level down.”
She added: “I think the question is, how does one get enough funds to compensate people for lost wages, especially for people in the gig economy and [the] precarious economy quickly and without complicated forms?”