People who've been inoculated with the BNT162b2 coronavirus vaccine from Pfizer (PFE 0.23%) and BioNTech (BNTX 0.55%) can look forward to its protection lasting for a minimum of six months.

On Thursday, the two companies released a top-line analysis from 927 confirmed cases of COVID-19, the disease triggered by the coronavirus. This indicates that the jab was over 91% effective against the affliction -- an extremely high number for any vaccine. Very encouragingly, this was tracked from one week to six months after the recipients received their second shot of the two-shot BNT162b2.

Child getting a syringe jab from a medical professional.

Image source: Getty Images.

The worse the disease, the better the performance of the vaccine. Pfizer and BioNTech said it was more than 95% effective against severe COVID-19 as defined by the Food and Drug Administration, and 100% effective according to the standards of the Centers for Disease Control and Prevention (CDC).

The shot seems to block the so-called South African variant of the coronavirus, too. The two companies' study indicates that BNT162b2 produced a "robust" neutralizing response to the variant. Many healthcare authorities are worried by the variant, as it appears to be more highly contagious than the original strain of the coronavirus. Many experts have expressed concern that vaccines might not be as effective against it.

Pfizer and BioNTech added that no serious safety concerns were recorded with any participants in the trial, again up to six months after their receiving dose No. 2. The companies said they aim to submit detailed data from the trial for peer review and possible publication. 

Despite the good news, Pfizer stock barely inched up on Thursday, and was trounced by the 1.2% rise of the S&P 500 index. BioNTech, on the other hand, shot 4.3% higher.