More re: covid infection and immunization…

As we posted previously ……

In their original application for approvals, the vaccine companies cited clinical studies demonstrating very high protection from symptomatic infection.

in Pfizer’s recent application to get an Emergency Use Authorization for booster shots, the company submitted data indicating that effectiveness against infection starts high (90% immediately after the 2nd shot) …  but it wanes down to around 40% 6 months later.


The good news: Confirmation of symptomatic infection protection soon after getting vaccinated.

The bad news: A relatively quick waning of the infection protection.

Consistent with the Pfizer data…

CNN reports two real-world studies, published in the New England Journal of Medicine, provide some data that complements Pfizer’s.

One study looked at actual infections among the  population of Qatar — a small Gulf nation that’s nearly fully vaccinated.

The conclusions:

> Protection against hospitalization and death builds quickly and stays at above 90%,

> Protection against infection:

  • Builds rapidly after the first dose
  • Peaks in the first month after the second dose
  • Wanes after the first month, gradually at first but …
  • Accelerating after the fourth month  down to approximately 20% in subsequent months.

Key point: Protection against infection drops more than Pfizer’s reported: 20% vs. 40%.


A second study, in Israel, tracked 4,800 health care workers, measuring neutralizing antibodies — the immune system’s first line of defense against infection which correlates with protection against infection

The main conclusion:

Antibody levels wane rapidly after two doses of vaccine “especially among men, among persons 65 years of age or older, and among persons with immunosuppression.”

Key point: Protection against infection starts high but wanes quickly for high risk groups.


In combination, Pfizer’s data and these 2 studies seem to indicate:

> Pfizer’s vaccine provides a very  high level of protection against severe covid disease, hospitalization and death … and, that the protection “remains strong” with minimal waning.

> And, while the vaccine does provide substantial protection against infection early-on, that protection wanes quickly after a couple of months … especially for seniors and people with immune system issues.

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