Eli Lilly’s CEO Dave Ricks said while he is “pleased to hear about Pfizer’s news,” he does not think the announcement of a highly effective vaccine will replace the need for antibody treatments. Lilly’s COVID-19 antibody treatment received an emergency use authorization from the Food and Drug Administration Monday night, and Ricks said it is still an important treatment for the disease.

On Monday, Pfizer announced that its vaccine candidate was more than 90% effective in preventing COVID-19. Dr. Albert Bourla, CEO of Pfizer, said that now the world “can see the light at the end of the tunnel.”

But according to CNBC, Ricks said that “even in well-controlled other respiratory illness we still have vaccination and antibody therapy because some patients escape the vaccine and still get the condition.”

He pointed out that antibodies will likely play an important role in developing countries, where the vaccines may be difficult to obtain.

According to the South China Morning Post, our bodies make antibodies to ward off foreign substances such as viruses. An antibody treatment is not a vaccine and does not provide permanent protection against SARS-CoV-2, the virus that causes COVID-19. The protection offered by the antibodies is short-lived but works right away.

President Donald Trump received antibody therapy from Regeneron Pharmaceuticals for his COVID-19 diagnosis last month. Former New Jersey Governor Chris Christie was treated with the Lilly drug.

The Lilly drug, called LY-CoV555, works by neutralizing the spike protein on the SARS-CoV-2 virus. It was manufactured by using the blood from one of the first U.S. recovered patients. No adverse side effects have been detected in clinical trials.

“The interim data suggests that LY-CoV555 has a direct antiviral effect and may reduce COVID-related hospitalizations,” said Dr. Daniel Skovronsky, M.D., the chief medical officer for Lilly, according to the Post. “The results reinforce our conviction that neutralizing antibodies can help in the fight against COVID-19.”

The results of a study published in the New England Journal of Medicine confirmed that only 1.6% of patients who received the Lilly antibody required hospitalization compared to 6.3% of people who received the placebo.