Britain must start “intense preparations” for a second wave of coronavirus that has the potential to kill as many as 120,000 hospital patients in a worst case scenario, experts have warned. Senior doctors and scientists convened by the Academy of Medical Sciences said on Tuesday that, without urgent action, a resurgence of cases this winter could overwhelm the NHS when services are already stretched because of flu and other seasonal pressures. The experts were commissioned by Sir Patrick Vallance, the government’s chief scientific adviser, to model a “reasonable worst case scenario” for Covid-19 this winter. Their report, which has been shared with ministers and local health authorities, calls for immediate efforts to prepare for a second wave. Compiled by 37 experts, the report stresses the worst case scenario is not a prediction of what is likely to happen, but a description of how the outbreak may evolve if infections are allowed to surge and little is done to prepare the NHS and social care services. “The modelling suggests that deaths could be higher with a new wave of Covid-19 this winter, but the risk of this happening could be reduced if we take action immediately,” said Stephen Holgate, chair of the expert group and professor of immunopharmacology at the University of Southampton. “With relatively low numbers of Covid-19 cases at the moment, this is a critical window of opportunity to help us prepare for the worst that winter can throw at us.” The virus may bounce back in the winter as the weather and dark evenings force people to spend more time indoors. In the summer, it is easier to keep homes and offices ventilated with open windows which allow breezes to replenish stale air. The reasonable worst case scenario assumes that the R value, the average number of people an infected person passes the disease on to, roughly doubles from around 0.9 in England today to 1.7 across the UK in September. The modelling suggests hospital admissions and deaths would peak in January and February 2021 with a similar number of deaths as in the first wave. The modelling excludes deaths in care homes and the community, assumes no government intervention to prevent transmission, and does not factor in the use of dexamethasone, a drug recently shown to save lives in intensive care units. Further modelling in the report shows less severe second waves might lead to 1,300 or 75,000 deaths between September 2020 and June 2021 if the R value rises to 1.1 or 1.5 respectively. The report calls for a major public information campaign in the autumn to encourage people to prevent the virus from spreading. Hospitals and care homes will need better supplies of personal protective equipment (PPE), widespread testing capacity and Covid-19-free zones. Because a second wave may coincide with the flu season, the experts said it was crucial that health and care workers, along with school children and all vulnerable individuals, received the flu vaccine. The report came as Matt Hancock, the health secretary, claimed the government had procured enough vaccine to roll out the “biggest flu vaccination programme in history”. The NHS test and trace system must be ramped up in time for the winter, Holgate said, as more people will be falling ill with infections that resemble Covid-19, and near real-time surveillance should be in place to spot local outbreaks. “We do need to take this threat of a new wave of Covid-19 very seriously but, if we prepare now, there is a lot we can do to minimise the risk,” he said. Dame Anne Johnson, a co-author of the report and professor of infectious disease epidemiology at University College London, said there was a need for a powerful public information campaign that targeted specific communities as well as the nation as a whole. “Everybody needs to realise that Covid-19 hasn’t gone away, and therefore everybody can help reduce transmission by social distancing, by the wearing of face coverings as a social norm, by good respiratory and hand hygiene and the right level of heating and ventilation in our homes,” she said. Every winter hospitals experience a surge in patients as seasonal flu sweeps through the population, people have more falls on icy pavements, and the cold weather exacerbates health problems such as asthma, heart disease and lung conditions. “This winter we have to factor in the likelihood of another wave of coronavirus infections and the ongoing impacts of the first wave. We have to be prepared that we might also experience a flu epidemic this year,” Johnson said. “Faced with these potential challenges, and after an already tough year, it would be easy to feel hopeless and powerless,” she added. “But this report shows that we can act now to change things for the better. We need to minimise coronavirus and flu transmission everywhere, and especially in hospitals and care homes. We need to get our health and social care, and the track, trace and isolate programme, ready for winter. This can be done, but it must be done now.”