Pfizer Says Early Data Shows Its Coronavirus Vaccine Is 90 Percent Effective

Pharmaceutical company Pfizer announced on Monday that the coronavirus vaccine it has been developing is showing more than 90 percent effectiveness. According to a report by CNN, this represented the results of an "interim analysis" of the drug's testing, based on the study of over 43,000 subjects. Pfizer believes it could have more conclusive results by the third week of November.

Pfizer gave two doses of either its COVID-19 vaccine or a placebo to the thousands of subjects in this experiment. They then watched for cases of the coronavirus within that group, and so far have followed up on 94 cases in total. Among those 94 cases, less than 10 percent of positive COVID-19 cases were identified in patients who had been given the actual vaccine, while more than 90 percent of COVID-19 cases were in placebo cases. This was above the efficacy that the drugmaker had even hoped for, and if the trend continues, could earn this vaccine emergency use authorization from the U.S. Food and Drug Administration.

Pfizer's plan from here is to monitor at least 164 confirmed coronavirus cases out of the 43,000+ test subjects, waiting to see what percentage of them got the trial vaccine. If the results stay favorable, the company will have met the FDA's criteria to apply for emergency use authorization, and the vaccine may be approved. Pfizer estimates it will reach this benchmark by the third week of this month, though there are factors that are hard to account for.

"With today's news, we are a significant step closer to providing people around the world with a much-needed breakthrough to help bring an end to this global health crisis," said Pfizer CEO Albert Bourla in a statement. "We look forward to sharing additional efficacy and safety data generated from thousands of participants in the coming weeks."

Pfizer's prospective vaccine is administered in two doses, about four weeks apart. The developers believe the first dose will provide protection against COVID-19 for 28 days, and the second dose for another seven days. However, the company has even higher hopes for the vaccine in the long-term — possibly seeking to aid patients who are now suffering from the mysterious long-term effects of this virus, which are being called "long COVID."


Pfizer also says more study is required to determine whether the vaccine is effective against all strains and severities of the virus, or whether a particularly harsh infection might get past it. Additionally, there is still some question about the efficacy of patients of different racial and ethnic backgrounds — only 30 percent of trial sites in the U.S. included volunteers of diverse backgrounds. Elsewhere, it was 42 percent.