The Food and Drug Administration on Monday approved the first new medication for Alzheimer’s disease in nearly two decades, a contentious decision, made despite opposition from the agency’s independent advisory committee and some Alzheimer’s experts who said there was not enough evidence that the drug can help patients.

The drug, aducanumab, which will go by the brand name Aduhelm, is a monthly intravenous infusion intended to slow cognitive decline in people with mild memory and thinking problems. It is the first approved treatment to attack the disease process of Alzheimer’s instead of just addressing dementia symptoms.

Biogen, its manufacturer, announced Monday afternoon that the list price would be $56,000 a year. In addition, there will most likely be tens of thousands of dollars in costs for diagnostic testing and brain imaging.

Recognizing that clinical trials of the drug had provided incomplete evidence to demonstrate effectiveness, the F.D.A. granted approval for the drug to be used but required Biogen to conduct a new clinical trial.

If the new trial, called a Phase 4 trial, fails to show the drug is effective, the F.D.A. can — but is not required to — rescind its approval.

About six million people in the United States and roughly 30 million globally have Alzheimer’s, a number expected to double by 2050. Currently, five medications approved in the United States can delay cognitive decline for several months in various Alzheimer’s stages.

Patient advocacy groups had lobbied vigorously for approval because there are so few treatments available for the debilitating condition. Some other drugs in clinical trials are more promising, but they are most likely three or four years away from potential approval.

The F.D.A. advisory committee, along with an independent think tank and several prominent experts — including some Alzheimer’s doctors who worked on the aducanumab clinical trials — said the evidence raised significant doubts about whether the drug is effective. They also said that even if it could slow cognitive decline in some patients, the benefit suggested by the evidence would be so slight that it would not outweigh the risk of swelling or bleeding in the brain that the drug caused in the trials.

“The data included in the applicant’s submission were highly complex and left residual uncertainties regarding clinical benefit,” the F.D.A.’s director of the Center for Drug Evaluation and Research, Dr. Patrizia Cavazzoni, wrote on the agency’s website.

Hanoi: After successfully containing the virus for the almost a full year, Vietnam on Saturday detected a new coronavirus variant that is a combination of the Indian and UK COVID-19 variants and authorities said that the variant can spread quickly by air. At this moment, the country is grappling with a rise in infections since late April that accounts for more than half of the total 6,856 registered cases. So far, there have been 47 deaths recorded in the country.

“Vietnam has uncovered a new COVID-19 variant combining characteristics of the two existing variants first found in India and the UK,” Health Minister Nguyen Thanh Long told news agency Reuters.

He said that the new coronavirus variant is an Indian variant with mutations that originally belong to the UK variant is very dangerous. Notably, Vietnam had previously detected seven virus variants: B.1.222, B.1.619, D614G, B.1.1.7 – known as the UK variant, B.1.351, A.23.1 and B.1.617.2 – the “Indian variant”

On the other hand, the World Health Organization (WHO) has also identified four variants of SARS-CoV-2 of global concern. These include variants that emerged first in India, Britain, South Africa and Brazil.

However, the country which has about 98 million people so far received only 2.9 million doses and aims to secure 150 million this year.

The health minister, however, did not specify the number of cases recorded with this new variant but said Vietnam will soon announce the discovery in the world’s map of genetic strains.

There were seven known coronavirus variants in Vietnam before Long’s announcement, according to the Ministry of Health.