"We don't know how long the vaccine protects against serious illness and death," said Karolinska Institute Professor Matti Sällberg.

"This means that you pick the safe before the unsafe."

Numerous European countries are planning a 3rd round of COVID "booster shots" in September, and the FDA also indicated that vaccinated individuals will be given another shot in the fall.

However, Sällberg suggests this probably won't be enough and that "recurring shots" will be necessary.

"After receiving the second dose, the immune response slowly subsides. Within a year, many may have lost their protection. We do not know yet, but if you get a third dose, it will be activated again," he said.

"Biology says that a fading immune response is not unlikely. Then it's time for a third, fourth, maybe fifth dose".

One wonders whether Sällberg holds a conflict of interest given that he is also chairman of the board at vaccine company SVF.

Meanwhile, in Israel, a doctor warned that "the effectiveness of the vaccine is waning/fading out" and that "85-90% of the hospitalizations are in fully vaccinated people."