Epidemiologist Neil Ferguson painted the grimmest of pictures: 2.2 million dead people in the U.S., 500,000 in the U.K.

His Imperial College London model was heavily cited, including by The New York Times, and has helped guide government decision-making, which has occasionally bordered on hysteria.

But Ferguson also said that things could change if governments took strong action to slow the virus and “flatten the curve” — the upward swing of the number of infected.

Earlier this week, Ferguson — who himself has contracted the virus — testified before the Houses of Parliament and said the death toll in the U.K. could be less than 20,000.

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“He said that expected increases in National Health Service capacity and ongoing restrictions to people’s movements make him ‘reasonably confident’ the health service can cope when the predicted peak of the epidemic arrives in two or three weeks. UK deaths from the disease are now unlikely to exceed 20,000, he said, and could be much lower,” New Scientist reported.

The need for intensive care beds will get very close to capacity in some areas, but won’t be breached at a national level, said Ferguson. The projections are based on computer simulations of the virus spreading, which take into account the properties of the virus, the reduced transmission between people asked to stay at home and the capacity of hospitals, particularly intensive care units. The Imperial model has played a key role in informing the UK’s coronavirus strategy, but this approach has been criticised by some. “To be fair, the Imperial people are the some of the best infectious disease modellers on the planet,” Paul Hunter at the University of East Anglia, UK, told New Scientist last week. “But it is risky to put all your eggs in a single basket.”

In his testimony, Ferguson said more people than expected likely have the virus (for most people, there are only mild symptoms). “I should admit, we’ve always been sensitive in the analysis in the modeling to a variety of levels or values to those quantities. What we’ve been seeing, though, in Europe in the last week or two is a rate of growth of the epidemic which was faster than we expected from early data in China. And so we are revising our quotes, our central best estimate of the reproduction… something more, a little bit above of the order of three or a little bit above rather than about 2.5.”

With more people than expected, the death drops (since the fatality rate is hovering around 1%). Researchers at Oxford say possibly half the U.K. population has already been infected, The Financial Times reported.

On March 17, Ferguson and his colleagues issued catastrophic predictions that if the U.K. did nothing more than 500,000 citizens would die from coronavirus, and that even with some mitigation efforts it “would still result in about 250,000 deaths and completely overwhelm intensive care in the NHS,” the BBC reported.

But with the new numbers, Ferguson said: “There will be some areas that are extremely stressed but we are reasonably confident — which is all we can be at the current time — that at the national level we will be within capacity.”