How do COVID vaccines’ effectiveness stack up against prior vaccines?

Answer: 95% is sky high compared to previous flu and pandemic virus vaccines.

Today, let’s put the current COVID vaccines into perspective.

September 2019 White House report looked specifically at flu and coronavirus vaccines, noting that….

There is considerable variation from year to year in how much the flu vaccine reduces the risk of contracting the seasonal flu and flu-related illnesses.

Over the past 14 years, influenza vaccine effectiveness has ranged between 10% and 60%.


Much of the variability depends on which viral strains predominate in a given year and, more specifically, whether the vaccine matches the viral strain that is circulating in a given flu season.

Although a mismatch between the vaccine and the virus circulating during a flu season reduces efficacy, vaccines still provide some protection against flu illness and decrease the severity of the illness, due to immunologic similarity between the viruses.


When it comes to pandemic viruses


The rarity of pandemics makes it hard to determine vaccine effectiveness during pandemics.

A monovalent A(H1N1) vaccine was developed for the 2009-2010 swine flu pandemic.

That vaccine was 62% effective in protecting people under age 65 years …

…  and 43% effective for those age 65 and older (the age group at highest risk of medical complications and death).


Bottom Line: The 95% reported by Pfizer and Moderna are, by historical standards, sky high.

Tomorrow, we’ll dig a little deeper on the 95% number…



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