Though the world has made progress in ending the Ebola epidemic, reports from Guinea, Liberia, and Sierra Leone suggest the fight against Ebola isn't over, according to correspondence from the World Health Organization published online today by The New England Journal of Medicine. Fewer people are being infected, but successes against the disease have been unevenly distributed, and the outbreak isn't under control.

As of Monday, there were 19,340 Ebola cases and 7,518 deaths, mostly in West Africa, according to the WHO. Sierra Leone had the greatest number of cases, 8,939 — almost half of all reported illnesses. Liberia had 7,830, a decrease; and Guinea had 2,571, with an incidence that the WHO described as "fluctuating." The disease seems to be slowing in Sierra Leone, and the response to Ebola in all three countries — the hardest-hit by the outbreak — has significantly strengthened, the WHO said.

The situation is considerably better than a projection in September, when health officials unveiled a worst-case scenario of 1.5 million infections by January if nothing was done to stop the disease's spread. Even when that estimate was released, officials from the US Centers for Disease Control and Prevention suggested that level of infection would be unlikely, since more aid was already reaching the most-affected countries in West Africa.

These charts, from the report, show at top the number of people infected by each sick person (the case reproduction number). The lower panels show the observed and projected weekly incidence of confirmed and probable Ebola cases. (WHO Ebola Response Team)

Until international intervention, the hospitals in West Africa were overwhelmed. But by December 14th, the most recent data available for the NEJM report, the total number of beds exceeded the number of Ebola patients reported each week — reflecting decreasing numbers of infection and increasing aid. But some areas fared better than others, the report said. Gaps in care remained in western Sierra Leone; the southeastern forest area and some northern districts of Guinea; and in western Liberia. And though about 200 trained burial teams helped lessen the risk of infection from contact with the dead, deaths that weren't reported to health authorities may still pose a hazard.

Sierra Leone has banned caroling, holiday parties, and other Christmas festivities

A case study from the Freetown area of Sierra Leone also appeared in The New England Journal of Medicine, showing a much lower case fatality rate than previously reported. About one-third of the 581 patients who were seen by doctors at the Hastings Police Training School near Freetown died — which is a lot of deaths, but a considerably lower fatality rate than had been previously reported. The previous study, of 108 Ebola patients in Sierra Leone, showed that almost three-quarters of patients who came to the hospital died.

It's not clear why the fatality rate at Hastings was lower than the earlier report's, since multiple things were done differently there, the authors wrote. But the decreased fatality rate is a glimmer of hope, suggesting that some progress has been made in combatting the disease.

it's too early to declare victory

The fight's not over, though. While patients in the hardest-hit areas now have access to treatment centers that didn't exist as recently as six months ago, it's too early to declare victory, writes Jeffrey Drazen, the editor-in-chief of The New England Journal of Medicine, in an editorial co-signed by three other experts. More volunteers and resources will be needed to make sure that the fight against Ebola in West Africa isn't still ongoing a year from now, they write.

In an attempt to control the outbreak, Sierra Leone has banned caroling, holiday parties, and other Christmas festivities that could give Ebola more opportunities to spread, according to the AP. Today, the country declared a lockdown in the north, with an exception for Christmas, according to the AFP.

"To deliver a victory, we need more volunteers who are willing to serve, to live in austere conditions, and to put themselves in harm's way," they write. "All estimates indicate that the number of personnel needed far exceeds the current supply."