The Pfizer coronavirus vaccine candidate may be more effective than the first suggested results.
Just one week after publishing provisional results that suggested the vaccine was more than 90 percent effective (SN: 11/9/20), the pharmaceutical giant and its German biotechnology partner BioNTech announced the final results of its clinical trial of 41,000 people. A final analysis indicates that the vaccine is 95 percent safe and effective in preventing disease, companies announced on Nov. 18. The results, shared in a press release, have not yet been reviewed by other scientists.
The final results depended on having a certain number of infections in the study group. It can usually take months to count the cases needed to determine final efficacy, but infection rates in the United States have been so high that coronavirus cases have accelerated rapidly at trial, speeding up the schedule for analyzing final results.
Among 170 volunteers who contracted COVID-19, 162 obtained a placebo. Only eight cases were reported in the group that received the vaccine.
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The efficacy of the Pfizer vaccine is comparable to the preliminary results of the Moderna vaccine trial, announced on November 16 (SN: 16/11/20). Both vaccines use messenger RNA or mRNA to carry instructions to make the coronavirus ear protein to human cells. Human cells read these instructions and produce the viral protein, preparing the immune system to prevent the virus in case it is found later.
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The vaccine, which requires two separate shots a month, can also decrease the severity of the disease. During the trial 10 people became seriously ill. Nine of those people were in the placebo group, while one seriously ill person was in the vaccine group. Among people 65 and older, the vaccine was more than 94 percent effective, companies said. That’s good news, because vaccines are often not as effective in the elderly, because the immune systems tend to weaken with age.
Pfizer and BioNTech plan to apply to the U.S. Food and Drug Administration for emergency use authorization within a few days and say 50 million doses of the vaccine, enough to immunize about 25 million people, will be available by the end of the year.
The news comes as COVID-19 cases continue to skyrocket. As of Nov. 18, nearly 58 million people in the world have been infected and 1.3 million people have died, according to COVID-19 tracker at Johns Hopkins University. The United States leads the world in cases, with 11.4 million infections and nearly 249,000 deaths. More than 100,000 new cases and about 1,500 deaths are reported every day across the country, and many states are tightening or implementing new public health measures to counter the spread of the virus.