Wonderful news broke this AM as Pfizer announced its COVID-19 vaccine was over 90% effective in preventing symptomatic infections. It means that immunity to the infection induced by the vaccine is effective in preventing illness after two doses of the vaccine, and given the high degree of efficacy vaccination should be able to end the pandemic.
The two-dose vaccine was found to be more than 90% effective at seven days after the second dose, Pfizer said, meaning that subjects were protected four weeks after their first shot.
This success validates the approach taken by “Operation Warp Speed” and justifies the risks undertaken to produce large numbers of vaccine doses before efficacy data was known. Given the high degree of success for the Pfizer vaccine, it is likely that other vaccines based on similar technology (Moderna) will likely also be successful. In fact, since most of the vaccines have the common approach of producing immunity to the SARS-CoV-2 spike protein, it is likely that most of the vaccines will work at least to some degree.
Several issues still need to be resolved. The full safety profile needs to be defined, and the first major read out from that should be available in a couple of weeks for the Pfizer vaccine. Given the trial was not stopped by the data safety monitoring board when it reviewed the result it is likely to be acceptable.
It will be interesting to note whether the vaccine prevents infection with the virus, which will lead to “herd immunity” that also protects other individuals or just prevents symptomatic illness. Finally, the duration of immune protection will be a question, but Pfizer’s CEO suggested that their earlier trial data indicates that the immunity will persist.
Regardless, this is the best news that could have been expected out of this trial. There is now hope for the world and a direct path out of the pandemic.