It is noted that the issue is about people at the age of 65-85, who have already received the third dose of the vaccine.
Meanwhile, people aged from 18 to 55 who had the third dose have five times higher level of antibodies against Delta strain than after the second dose.
Besides, according to Pfizer, the level of antibodies after the third dose is notably higher than after the second dose against the original variant of coronavirus and Beta variant that was found in South Africa.
As we reported, the covid vaccines from Pfizer/BioNTech and AstraZeneca are highly efficient against the Delta strain. Two doses of Pfizer vaccine appeared to be 88% effective against the infection caused by the Delta strain. The full course of vaccination with the AstraZeneca drug showed 67% efficiency. Two doses of Pfizer and AstraZeneca are considered almost just as much effective against the Alpha strain. The difference in the efficiency levels was minimal.