It is not clear how the Department of Health and Social Care is assessing whether the NHS has enough critical care equipment for future demand. NHSE&I’s estimate of how many mechanical ventilators the NHS would need in a worst-case scenario has changed repeatedly: on 12 February initial estimates indicated a need of up to 59,000, by early March this had increased to 90,000, before reducing to 17,500 on 24 March and again to just 6,200 by 8 April. On 15 April, after the peak of COVID-19 hospitalisations, the Department set targets of 18,000 ventilators by 30 April and 30,000 by 30 June to prepare for a potential second wave. It missed both these targets but eventually reached 30,000 by 3 August. It is fortunate that the majority of the ventilators were not needed and that additional capacity is now available should it be required. However, given its targets were not finely calibrated to need and the extent to which its estimates of need have varied, we are concerned that the Department has failed to set out how it now assesses the scale of future need. It told us that it no longer does ‘mathematical modelling’, but looks at the day-to-day situation. It is vital that the Department is transparent on how it assesses whether it has sufficient stocks of not only ventilators but also of any other equipment required to treat COVID-19 as the pandemic evolves. Recommendation: The Department of Health and Social Care should write to us within one month of this report explaining its current methodology for assessing 6 Covid-19: Supply of ventilators whether it has all the equipment it needs to respond effectively to the pandemic.