Twitter has said there is no evidence of bot networks being used to manipulate the conversation around the coronavirus pandemic in the UK, contradicting widely-circulated claims that the government was using anonymous online accounts to boost its standing.

Quick guide Will there be a second wave of coronavirus? Show Hide In recent days the UK has seen a sudden sharp increase in Covid-19 infection numbers, leading to fears that a second wave of cases is beginning. Epidemics of infectious diseases behave in different ways but the 1918 influenza pandemic that killed more than 50 million people is regarded as a key example of a pandemic that occurred in multiple waves, with the latter more severe than the first. It has been replicated – albeit more mildly – in subsequent flu pandemics. Until now that had been what was expected from Covid-19.

How and why multiple-wave outbreaks occur, and how subsequent waves of infection can be prevented, has become a staple of epidemiological modelling studies and pandemic preparation, which have looked at everything from social behaviour and health policy to vaccination and the buildup of community immunity, also known as herd immunity. Is there evidence of coronavirus coming back in a second wave? This is being watched very carefully. Without a vaccine, and with no widespread immunity to the new disease, one alarm is being sounded by the experience of Singapore, which has seen a sudden resurgence in infections despite being lauded for its early handling of the outbreak. Although Singapore instituted a strong contact tracing system for its general population, the disease re-emerged in cramped dormitory accommodation used by thousands of foreign workers with inadequate hygiene facilities and shared canteens. Singapore’s experience, although very specific, has demonstrated the ability of the disease to come back strongly in places where people are in close proximity and its ability to exploit any weakness in public health regimes set up to counter it. In June 2020, Beijing suffered from a new cluster of coronavirus cases which caused authorities to re-implement restrictions that China had previously been able to lift. In the UK, the city of Leicester was unable to come out of lockdown because of the development of a new spike of coronavirus cases. Clusters also emerged in Melbourne, requiring a re-imposition of lockdown conditions. What are experts worried about? Conventional wisdom among scientists suggests second waves of resistant infections occur after the capacity for treatment and isolation becomes exhausted. In this case the concern is that the social and political consensus supporting lockdowns is being overtaken by public frustration and the urgent need to reopen economies. However Linda Bauld, professor of public health at the University of Edinburgh, says “‘Second wave’ isn’t a term that we would use at the current time, as the virus hasn’t gone away, it’s in our population, it has spread to 188 countries so far, and what we are seeing now is essentially localised spikes or a localised return of a large number of cases.” The overall threat declines when susceptibility of the population to the disease falls below a certain threshold or when widespread vaccination becomes available. In general terms the ratio of susceptible and immune individuals in a population at the end of one wave determines the potential magnitude of a subsequent wave. The worry is that with a vaccine still many months away, and the real rate of infection only being guessed at, populations worldwide remain highly vulnerable to both resurgence and subsequent waves. Peter Beaumont, Emma Graham-Harrison and Martin Belam

Unverified claims that the Department for Health and Social Care had been running fake social accounts were widely shared by journalists, politicians, and leading public figures in the last two days. The claims were also written up by some outlets such as the blog Skwawkbox – which described the supposed scandal as the next “Cambridge Analytica”.

The accusations were first made by John O’Connell, a writer for the website Far Right Watch. He claimed to have identified 128 Twitter accounts which had been set up by individuals associated with either the DHSC or unidentified marketing agencies working for the government.

In his telling, this purported linked network of accounts were being coordinated to promote the concept of herd immunity and boost the government’s messaging. He also claimed to have identified four individuals running the accounts, which he says have since all been deleted, but has yet to release their names.

So far he has only provided details of one of the 128 accounts supposedly involved in the disinformation network: a recently-deleted spoof Twitter profile with fewer than 200 followers which used a profile picture stolen from a real NHS nurse.

The account, which O’Connell claimed was boosting the government message, posed as a fake person – a deaf, non-binary NHS nurse who wanted to end the weekly celebration for NHS workers because it excluded her as she could not hear the clapping.

O’Connell publicly claimed that the government was hoping his claims would “be swept aside by ongoing news stories of a more serious nature … After all, who cares about industrial scale misinformation in the face of so many deaths?”

On Tuesday morning he promised further revelations but said he could not yet reveal his evidence, saying he was concerned about repercussions: “We’re analysing the data and seeking a way of presenting it while protecting ourselves from legal issues. We know what happened to those that blew the whistle on Cambridge Analytica.”

However, Twitter has now said they do not have any evidence on their systems to support his accusations.

“Our specialist teams currently do not see evidence of large-scale coordinated platform manipulation surrounding the Covid-19 conversation, including suggested coordination associated with the UK government,” said a spokesperson for the social network.

“As is standard, we will remove any pockets of smaller coordinated attempts to distort or inorganically influence the conversation We are continuing to review and require the removal of tweets that do not follow the Twitter rules – half of which we catch before they’re ever reported to us. If people see anything suspicious on our service, please report it to us. This is an evolving global conversation and we will remain vigilant.”

In response O’Connell told the Guardian that Twitter is denying his claims in order to “protect the integrity of their platform”.

He insisted he was in no rush to publish the evidence as it “is not presentable as yet” and he is concerned about legal protections. “One step at a time, I know is not the media way, but it has to be so.”

A spokesperson for the Department for Health and Social Care said: “The claims are not only wild but completely false. The individual making the claims has provided no evidence to back up his assertion that DHSC were involved, even when directly asked by people other than the department for his ‘evidence’.”

“Sharing unsubstantiated online claims like this could damage the national effort against coronavirus and we would urge people not to do so.”