The Times of India claims that:
With intramuscular vaccines (most of the COVID-19 vaccine shots are delivered through this mean right now), rubbing, pinching or massaging the injection site may interfere with the effectiveness of the vaccine. While it may seem to relieve and quench the soreness that follows inoculation, massaging at the point may seldom cause the drug to back up through the subcutaneous tissue present in the deepest layer of your skin, so, as a safety measure, massages or hard rubs are best avoided for the time being.
Is this any true? (e.g. Does it matter if I hardly press the arm or mildly?)